98170 • Lifestyle and Cancer Risk: What We Do (and Do Not) Know

Table of Contents

98170 • Lifestyle and Cancer Risk: What We Do (and Do Not) Know

How to Receive Credit

Course Overview

Audience

Accreditations & Approvals

Designations of Credit

Individual State Nursing Approvals

Special Approvals

Course Objective

Learning Objectives

Faculty

Faculty Disclosure

Division Planners

Division Planners Disclosure

Director of Development and Academic Affairs

Director Disclosure Statement

About the Sponsor

Disclosure Statement

Implicit Bias in Health Care

1. INTRODUCTION

2. EARLY DETECTION

3. DIETARY INTERVENTIONS

ALCOHOL CONSUMPTION

ARTIFICIAL SWEETENERS

COOKED MEAT

CRUCIFEROUS VEGETABLES

ORGANIC FOODS

SOY

DIETARY SUPPLEMENTS

GENERAL DIETARY CONSIDERATIONS

4. OTHER LIFESTYLE INTERVENTIONS

PHYSICAL ACTIVITY

WEIGHT MANAGEMENT

SUN EXPOSURE

TOBACCO USE

5. CONCLUSION

Works Cited

Evidence-Based Practice Recommendations Citations

98170 • Lifestyle and Cancer Risk: What We Do (and Do Not) Know

Chelsey McIntyre, PharmD

www.netce.com

Copyright © 2025 NetCE, All rights reserved.

Cancer fear and methods of cancer prevention remain prevalent in the public conversation. This has led to an array of claims regarding lifestyle choices (and products) that may help to reduce a person's cancer risk. Unfortunately, due to the many factors contributing to the development of cancer, no person can guarantee an avoidance of cancer regardless of how many preventive measures are taken. Further, not all preventive measures are created equal. While certain lifestyle changes have been strongly correlated to cancer risk reduction, many lack supportive evidence. Despite this lack of supportive evidence (and, in some cases, evidence indicating no benefit), cancer prevention via supplementation, diet, and lifestyle continues to capture national attention. This course will review the lifestyle choices that are most often discussed in relation to cancer prevention, in conjunction with any associated evidence.

98170 • Lifestyle and Cancer Risk: What We Do (and Do Not) Know

Education Category. Alternative Medicine

Release Date. 06/01/2025

Expiration Date. 05/31/2028

How to Receive Credit

To complete this course for continuing education credit please go to http://www.netce.com/course/3118 in your browser.

For assistance with receiving continuing education credit, please contact us at help@netce.com.

Course Overview

Cancer fear and methods of cancer prevention remain prevalent in the public conversation. This has led to an array of claims regarding lifestyle choices (and products) that may help to reduce a person's cancer risk. Unfortunately, due to the many factors contributing to the development of cancer, no person can guarantee an avoidance of cancer regardless of how many preventive measures are taken. Further, not all preventive measures are created equal. While certain lifestyle changes have been strongly correlated to cancer risk reduction, many lack supportive evidence. Despite this lack of supportive evidence (and, in some cases, evidence indicating no benefit), cancer prevention via supplementation, diet, and lifestyle continues to capture national attention. This course will review the lifestyle choices that are most often discussed in relation to cancer prevention, in conjunction with any associated evidence.

Audience

This course is designed for physicians, nurses, pharmacy professionals, and other healthcare professionals involved in cancer prevention and lifestyle change efforts.

Accreditations & Approvals

In support of improving patient care, TRC Healthcare/NetCE is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team. NetCE is accredited by the International Accreditors for Continuing Education and Training (IACET). NetCE complies with the ANSI/IACET Standard, which is recognized internationally as a standard of excellence in instructional practices. As a result of this accreditation, NetCE is authorized to issue the IACET CEU.

Designations of Credit

This activity was planned by and for the healthcare team, and learners will receive 2.5 Interprofessional Continuing Education (IPCE) credit(s) for learning and change. NetCE designates this enduring material for a maximum of 2.5 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity. NetCE designates this continuing education activity for 2.5 ANCC contact hour(s). NetCE designates this continuing education activity for 3 hours for Alabama nurses. NetCE designates this activity for 2.5 ACPE credit(s). ACPE Universal Activity Number: JA4008164-0000-25-035-H04-P. Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 2.5 MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program. Participants will earn MOC points equivalent to the amount of CME credits claimed for the activity. It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit. Completion of this course constitutes permission to share the completion data with ACCME. This activity has been approved for the American Board of Anesthesiology’s® (ABA) requirements for Part II: Lifelong Learning and Self-Assessment of the American Board of Anesthesiology’s (ABA) redesigned Maintenance of Certification in Anesthesiology Program® (MOCA®), known as MOCA 2.0®. Please consult the ABA website, www.theABA.org, for a list of all MOCA 2.0 requirements. Maintenance of Certification in Anesthesiology Program® and MOCA® are registered certification marks of the American Board of Anesthesiology®. MOCA 2.0® is a trademark of the American Board of Anesthesiology®. Successful completion of this CME activity, which includes participation in the evaluation component, enables the learner to earn credit toward the CME and/or Self-Assessment requirements of the American Board of Surgery's Continuous Certification program. It is the CME activity provider's responsibility to submit learner completion information to ACCME for the purpose of granting ABS credit. Successful completion of this CME activity, which includes participation in the activity with individual assessments of the participant and feedback to the participant, enables the participant to earn 2.5 MOC points in the American Board of Pediatrics' (ABP) Maintenance of Certification (MOC) program. It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting ABP MOC credit. This activity has been designated for 2.5 Lifelong Learning (Part II) credits for the American Board of Pathology Continuing Certification Program. Through an agreement between the Accreditation Council for Continuing Medical Education and the Royal College of Physicians and Surgeons of Canada, medical practitioners participating in the Royal College MOC Program may record completion of accredited activities registered under the ACCME's "CME in Support of MOC" program in Section 3 of the Royal College's MOC Program. NetCE is authorized by IACET to offer 0.25 CEU(s) for this program. AACN Synergy CERP Category A.

Individual State Nursing Approvals

In addition to states that accept ANCC, NetCE is approved as a provider of continuing education in nursing by: Alabama, Provider #ABNP0353 (valid through July 29, 2025); Arkansas, Provider #50-2405; California, BRN Provider #CEP9784; California, LVN Provider #V10662; California, PT Provider #V10842; District of Columbia, Provider #50-2405; Florida, Provider #50-2405; Georgia, Provider #50-2405; Kentucky, Provider #7-0054 through 12/31/2025; South Carolina, Provider #50-2405; West Virginia RN and APRN, Provider #50-2405.

Special Approvals

This activity is designed to comply with the requirements of California Assembly Bill 1195, Cultural and Linguistic Competency.

Course Objective

The purpose of this course is to provide healthcare professionals in all practice settings the knowledge necessary to increase their understanding of lifestyle factors' impact on cancer risk, with resultant improvements in patient counseling and care plans.

Learning Objectives

Upon completion of this course, you should be able to:

1. Review the evidence associated with dietary interventions for the prevention of cancer.

2. Identify at least three purported preventive strategies for which there is limited or no evidence of benefit.

3. Explain the evidence for the use of antioxidants for cancer prevention.

4. Discuss current recommendations for diet, physical activity, tobacco use, sun exposure, and weight management in relation to cancer prevention and overall health.

Faculty

Chelsey McIntyre, PharmD, is a clinical pharmacist who specializes in drug information, literature analysis, and medical writing. She earned her Bachelor of Science degree in Genetics from the University of California, Davis. She then went on to complete her PharmD at Creighton University, followed by a clinical residency at the Children’s Hospital of Philadelphia (CHOP). Dr. McIntyre held the position of Drug Information and Policy Development Pharmacist at CHOP until her move to Washington state in 2017, after which she spent the next six years as a clinical editor for Natural Medicines, a clinical reference database focused on natural products and alternative therapies. She continues to create rigorous professional analysis and patient education materials for various publications while also practicing as a hospital pharmacist. Her professional interests include provider and patient education, as well as the application of evidence-based research to patient care.

Faculty Disclosure

Contributing faculty, Chelsey McIntyre, PharmD, has disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.

Division Planners

John M. Leonard, MD

Mary Franks, MSN, APRN, FNP-C

Randall L. Allen, PharmD

Division Planners Disclosure

The division planners have disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.

Director of Development and Academic Affairs

Sarah Campbell

Director Disclosure Statement

The Director of Development and Academic Affairs has disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.

About the Sponsor

The purpose of NetCE is to provide challenging curricula to assist healthcare professionals to raise their levels of expertise while fulfilling their continuing education requirements, thereby improving the quality of healthcare.

Our contributing faculty members have taken care to ensure that the information and recommendations are accurate and compatible with the standards generally accepted at the time of publication. The publisher disclaims any liability, loss or damage incurred as a consequence, directly or indirectly, of the use and application of any of the contents. Participants are cautioned about the potential risk of using limited knowledge when integrating new techniques into practice.

Disclosure Statement

It is the policy of NetCE not to accept commercial support. Furthermore, commercial interests are prohibited from distributing or providing access to this activity to learners.

Implicit Bias in Health Care

The role of implicit biases on healthcare outcomes has become a concern, as there is some evidence that implicit biases contribute to health disparities, professionals' attitudes toward and interactions with patients, quality of care, diagnoses, and treatment decisions. This may produce differences in help-seeking, diagnoses, and ultimately treatments and interventions. Implicit biases may also unwittingly produce professional behaviors, attitudes, and interactions that reduce patients' trust and comfort with their provider, leading to earlier termination of visits and/or reduced adherence and follow-up. Disadvantaged groups are marginalized in the healthcare system and vulnerable on multiple levels; health professionals' implicit biases can further exacerbate these existing disadvantages.

Interventions or strategies designed to reduce implicit bias may be categorized as change-based or control-based. Change-based interventions focus on reducing or changing cognitive associations underlying implicit biases. These interventions might include challenging stereotypes. Conversely, control-based interventions involve reducing the effects of the implicit bias on the individual's behaviors. These strategies include increasing awareness of biased thoughts and responses. The two types of interventions are not mutually exclusive and may be used synergistically.

1. INTRODUCTION

Each year in the United States, approximately 1.9 million new cancer cases are diagnosed. Of these cases, the vast majority (99%) occur in adults. Among cancer cases in adults, the majority (80%) occur in those 55 years of age and older; 57% occur in those 65 years of age and older. Approximately 40% of people will develop cancer over the course of their entire lifetime, the most common of which will be lung, colorectal, breast, and prostate cancer [1].

These statistics do not include cancers that are not considered to be malignant. Specifically, this means that these statistics exclude: basal cell carcinoma, squamous cell carcinoma, and carcinoma in situ (sometimes referred to as stage 0) [1]. This is an important distinction to make, because basal cell and squamous cell carcinomas are the most common forms of cancer in the United States, with about 5.4 million diagnoses each year [2].

The good news is that cancer survival rates are increasing. Since 1990, cancer-related mortality has consistently declined every year [3]. Between 1991 and 2019, the rate of cancer-related deaths declined by 32%. Looking at this by the numbers: About 610,000 people in the United States die from cancer each year, whereas current estimates indicate that approximately 17 million living Americans have a history of invasive cancer [1].

Some of this improvement in survival can be tied to earlier detection of cancer. Regular screening is known to improve mortality rates in multiple types of cancer, including breast, colon, cervical, lung, and prostate cancer. Similarly, regular screening can allow for the identification and removal of certain types of precancerous lesions, such as those found in the colon or cervix [1].

A significant portion of this improvement in survival is also attributable to preventive measures. Approximately 42% of newly diagnosed cancers in the United States are considered "potentially avoidable," according to the American Cancer Society. These include about 19% of cancers which are caused by smoking and 18% of cancers that are caused by a combination of factors, including body weight, alcohol intake, nutrition, and physical activity levels. Additionally, cancers that are caused by infectious agents (e.g., human papillomavirus (HPV), hepatitis B or C, and Helicobacter pylori) can often be prevented via immunization and/or lifestyle changes [1].

However, not all preventive measures are created equal. While certain lifestyle changes have been strongly correlated to cancer risk reduction, many lack supportive evidence. Despite this lack of supportive evidence (and, in some cases, evidence indicating no benefit), cancer prevention via supplementation, diet, and lifestyle continues to capture national attention. This course will review the lifestyle choices that are most often discussed in relation to cancer prevention, in conjunction with any associated evidence.

2. EARLY DETECTION

Cancer screening, which often results in early detection, remains the most evidence-based method for improving cancer-related outcomes. Patients should be regularly evaluated for, and encouraged to participate in, recommended screening for early detection.

It is important to understand that cancer screening recommendations are dependent on individual risk factors. While some screening is recommended for all adults, regardless of risk level, high-risk individuals might be recommended to undergo earlier screening or screening for additional forms of cancer.

A person may be considered at high risk for cancer for a variety of reasons, including family history, personal medical history, environmental exposures, and more. It is important for patients to understand that family history is only one of many considerations in their overall risk for cancer. While there are certain forms of cancer that are genetic (hereditary)—meaning that the risk may be higher for close relatives—these represent only 5% to 10% of all cancers. The remaining 90% to 95% of cancers are likely to be due to other factors instead [4].

The National Comprehensive Cancer Network (NCCN) provides updated evidence-based practice guidelines and clinical resources for cancer prevention and screening by cancer type (https://www.nccn.org/guidelines/category_2). The American Cancer Society also provides cancer screening recommendations by cancer type and patient age (https://www.cancer.org/cancer/screening/american-cancer-society-guidelines-for-the-early-detection-of-cancer.html). Separately, the U.S. Preventive Services Task Force (USPSTF) provides screening guidelines for the most common forms of cancer (https://www.uspreventiveservicestaskforce.org). Although the specifics of these screening recommendations may differ somewhat between organizations, all of these organizations recommend screening for breast, cervical, colorectal, lung, and prostate cancer.

3. DIETARY INTERVENTIONS

Dietary interventions, which involve adding and removing certain ingredients from the diet, are commonly promoted for cancer prevention. However, the research regarding dietary interventions is almost exclusively observational, and much of it has yielded mixed and conflicting findings.

ALCOHOL CONSUMPTION

The occasional consumption of certain alcoholic beverages, such as wine, is often promoted by nonmedical resources for cancer prevention. This is uniquely concerning because the consumption of large quantities of alcohol has been definitively linked to an increased risk for certain types of cancer. In fact, in its Report on Carcinogens, the U.S. National Toxicology Program has listed alcoholic beverage consumption as a known human carcinogen since 2000 [5].

According to the Report on Carcinogens, alcohol consumption is most strongly associated with cancer of the mouth, pharynx, larynx, and esophagus; a weaker association exists between alcohol consumption and cancer of the liver and breast. The risk of cancer from alcohol consumption is highest in people who also smoke [5]. Other research has identified an increased risk between moderate to heavy alcohol consumption and colorectal cancer [6].

In general, the available evidence indicates that the more alcohol a person consumes, the higher the risk for a related cancer diagnosis. This research clearly indicates that heavy alcohol consumption carries the highest risk for cancer.

However, research also shows that even those with light-to-moderate alcohol consumption may have a modestly increased risk of certain cancers [7,8]. The World Health Organization (WHO) recently released a statement on this risk, which garnered significant media attention. For the purposes of the statement, light-to-moderate alcohol consumption was defined as less than 1.5 L of wine, 3.5 L of beer, or 0.45 L of spirits per week. The statement refers to data indicating that this level of alcohol consumption was identified as the cause of 23,000 new cancer cases in the European Union in 2017. This represented 13.3% of all alcohol-related cancers [9].

These numbers should be considered in the context of all cancer diagnoses, however. Only 2.3% of all cases of seven alcohol-related cancer types were attributed to light-to-moderate alcohol consumption that year [9]. Additionally, a retrospective review of cancer causes is inherently limited due to the many undocumented factors that can contribute to cancer development. While the researchers were unable to identify other apparent causes of cancer in these individuals—besides alcohol consumption—this does not mean that there were no other contributors to these cancers.

The American Cancer Society recommends that people generally avoid drinking alcohol. For those that do choose to drink alcohol, the organization recommends no more than one drink per day for women and two drinks per day for men. These recommendations assume that one drink is equivalent to 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of hard liquor [10].

Although the evidence supporting a link between alcohol consumption and cancer risk is strong, a recent survey found that more than 50% of adults do not know that alcohol impacts cancer risk. This understanding varied by the type of alcohol consumed, with about 10% of respondents stating that wine decreases cancer risk and about 30% of respondents stating that liquor increases cancer risk [11]. In reality, it is the total quantity of alcohol, not the type of alcohol, that affects cancer risk.

Considering that the strongest evidence evaluating alcohol consumption and cancer risk points to an increased risk for cancer, alcoholic beverages of any type should never be recommended as a preventive measure. Instead, the preventive recommendation should focus on either reducing or eliminating alcohol intake. With multiple studies indicating that alcohol use, and related mortality, has been on the rise in the United States since the COVID-19 pandemic, it may be more important than ever to ensure patients are appropriately informed and counseled on this risk [12].

ARTIFICIAL SWEETENERS

Artificial sweeteners are commonly vilified as cancer-causing additives that should be removed from the diet. These claims span the gamut of artificial sweeteners, including aspartame, sucralose, saccharin, and acesulfame, although the evidence for each specific sweetener differs.

Many claims of harm stem from small animal studies that have linked these chemicals with an increased risk for cancer, despite the fact that many of these studies used exceptionally high doses of sweeteners, and not all animal studies have yielded these same findings [13]. The majority of the available human research is observational, which makes it difficult to determine causation even in the presence of an apparent association.

One of the largest analyses of this topic to date involved an "umbrella review," or a systematic review of prior systematic reviews and meta-analyses. This umbrella review incorporated only reviews and analyses of research conducted in humans, ultimately finding only weak, non-significant evidence of a link between the use of artificial sweeteners and cancer risk. The correlation remained weak and non-significant for cancer-related mortality as well [14].

Reassure patients—especially those with health issues that warrant the use of artificial sweeteners—that the available evidence does not support removing artificial sweeteners from the diet for the purpose of cancer prevention.

The International Agency for Research on Cancer (IARC) recently labeled aspartame as a possible carcinogen, a decision that resulted in significant news coverage. Importantly, the decision to add this label to aspartame was based on "limited evidence" and did not require an associated change in the previously established acceptable daily intake of aspartame (40 mg/kg) [15].

In response to the IARC decision, the U.S. Food and Drug Administration (FDA) issued a statement clarifying that aspartame's classification as a possible carcinogen does not mean that it is actually linked to cancer. Rather, the FDA ultimately disagreed with the IARC's decision after conducting its own analysis of the existing data, which identified significant shortcomings [16].

COOKED MEAT

Cooked meat is sometimes discussed as a risk factor for certain types of cancer. This concern originated with the discovery that meats cooked at high temperatures over an open flame contain certain types of chemicals (i.e., heterocyclic amines [HCAs] and polycyclic aromatic hydrocarbons [PAHs]) that demonstrate mutagenic properties in laboratory research. In animal research, very high quantities of these chemicals were also found to cause cancer [17].

While some observational research in humans has found a possible correlation between consuming well-done, fried, or barbecued meat and an increased risk for colorectal, pancreatic, or prostate cancer, other observational studies have found no correlation [17].

For people who are concerned about whether they may be exposed to these carcinogens via the meats they eat, some small changes in cooking methods can make a big difference. For example, the risks for exposure to HCAs and PAHs are higher for meats that are cooked at high temperatures for extended durations, and those which are exposed to smoke while cooking. Flipping meat periodically can reduce the quantity of these carcinogens, as can removing charred portions of the meat before eating [17].

CRUCIFEROUS VEGETABLES

Over the years, there has been a growing conversation about the potential for cruciferous vegetables to prevent cancer. The term "cruciferous vegetables" refers to vegetables that fall into the Brassica family, some of the more common of which includes broccoli, cauliflower, cabbage, kale, collard greens, radishes, and turnips.

A group of sulfur-containing chemicals called glucosinolates, which are found in these vegetables, have been the primary driver behind this cancer prevention push. When cruciferous vegetables are prepared, chewed, or broken down in the body, they break down into a number of individual compounds. Two of these compounds (indole-3-carbinol and sulforaphane) have shown anticancer effects in some animal studies. This anticancer activity seems to stem from a number of different mechanisms, including protection against DNA damage, inactivation of carcinogens, and induction of cell death in damaged cells [18].

Unfortunately, as with other dietary interventions, any evidence of benefit in cancer prevention is limited and observational in nature. To date, some smaller cohort studies in Europe and the United States have suggested that increased intake of cruciferous vegetables may be correlated with a modestly reduced risk of certain types of cancers, including colorectal and prostate. However, other cohort studies have not identified a link between cruciferous vegetable intake and cancer risk [18].

There has also been interest in taking dietary supplements that provide sulforaphane and/or indole-3-carbinol. So far, studies of these supplements have been quite small and primarily focused on patients who already have cancer. The benefits of these supplements for reducing overall cancer risk remain unclear.

While there is currently no strong evidence to suggest that a diet high in cruciferous vegetables will reduce a person's risk of cancer, vegetables are an important part of a healthy and well-rounded diet. Patients should always be encouraged to increase their vegetable consumption, cruciferous or otherwise.

ORGANIC FOODS

At least three pesticides (glyphosate, malathion, and diazinon) are classified by the IARC as probably carcinogenic to humans [19]. Since these pesticides are used on foods which are regularly consumed in the diet, there has been increased interest in opting for organic foods, so as to reduce exposure to pesticides and reduce the risk of associated health issues, such as cancer.

Unfortunately, the evidence is not so straightforward. The rating granted to these three pesticides is primarily based on an association with cancer risk in animal research, whereas human evidence remains limited. Additionally, these ratings pertain to high-volume exposures to these pesticides, such as those that occur in farm workers who are applying the pesticides to crops [19]. This type of exposure differs greatly from exposures obtained from foods which were treated with pesticides (and may or may not have been washed in the interim).

It is unclear whether opting for organic foods will reduce a person's risk for cancer. Observational research on this topic has yielded conflicting findings, with some studies finding no clear association between the consumption of organic foods and cancer risk [20,21,22,23]. As with all observational dietary research, it is difficult to accurately assess a person's organic food intake over time. Additionally, people who choose to consume organic foods may also have other sociodemographic and lifestyle factors that could ultimately alter their cancer risk, confounding any findings.

Organic foods typically come at a significantly increased cost to the consumer. Considering that there is no clear benefit in relation to cancer risk, and that a number of studies indicate that the general nutritional content of organic foods is similar to their non-organic counterparts, there is no adequate evidence to support recommending that patients opt for organic foods.

SOY

Over the years, many rumors and myths have made the rounds regarding whether soy can increase a person's risk of cancer. To date, however, research has not validated these concerns. Population research has instead found that soy, as part of the diet or when taken as a supplement, may be protective against breast cancer. This research has consistently found that a high-soy diet in Asian and Asian American women is associated with a reduced risk of breast cancer. However, the amount of soy consumed in a Western diet, even among those who consume the highest amounts of soy, was not found to have a preventative effect [24].

Some early research suggested that soy supplements might stimulate the growth of breast tissue or endometrial cells. However, these findings have not been validated in prospective research.

One clinical study shows that taking a tablet containing 50 mg soy isoflavones daily for 12 months does not alter mammographic or breast MRI tissue density in those at high risk of breast cancer, those with non-endocrine treated breast cancer, or those previously treated for breast cancer and without recurrence [25]. Additionally, a study in adults taking high doses of soy isoflavones, such as 150 mg daily, for five years found no evidence that soy isoflavones increase the risk of atypical endometrial hyperplasia [26,27].

DIETARY SUPPLEMENTS

Antioxidants

Antioxidants are an incredibly popular cancer prevention strategy. Supplements, foods, and drinks often tout their antioxidant content for this reason. Antioxidants are hypothesized to prevent the development of cancer by binding with cancer-causing free radicals in the body. Although in vitro and animal research has supported this theory, these findings have not carried over to clinical research. Prospective clinical research evaluating the benefits of antioxidant supplements in preventing cancer have been overwhelmingly negative [28].

Vitamins and Minerals

Antioxidant vitamin supplements, including vitamins A, C, and E, have not shown benefit for preventing cancer overall, or for preventing prostate, lung, or gastric cancers, specifically. In fact, some studies even indicated a weak association towards an increased risk for cancer in some cases [28]. These findings, which showed a small increased risk of lung cancer in smokers, ultimately led to a USPSTF recommendation against the use of beta-carotene or vitamin E supplements for the prevention of cancer. The group also concluded that there was insufficient evidence to assess the balance of benefits and harms in using other vitamin and mineral supplements for the prevention of cancer [29].

Multivitamins are another popular supplement that has been studied for cancer prevention. Although some population research has linked multivitamin intake with a slightly reduced risk of colorectal cancer, other low-quality research has not found a link between multivitamin use and lung, breast, or prostate cancer. The USPSTF has concluded that evidence related to the use of multivitamins for cancer prevention remains limited and conflicting. For now, the evidence is too preliminary to make a recommendation [29].

Vitamin and mineral deficiencies can have a variety of health consequences, which may or may not include an increased risk of cancer. In general, everyone should seek to obtain adequate nutrition, covering all macro- and micronutrients, via a well-rounded diet. However, there is no evidence to support recommending vitamin or mineral supplements for patients who do not have a deficiency or known absorption disorder.

Lycopene

Lycopene, another commonly discussed antioxidant, is found in tomatoes and other fruits such as guava, apricots, and pink grapefruit. This particular antioxidant is most often promoted for the prevention of prostate cancer. These claims stem from observational research which has found that increased dietary consumption of lycopene is associated with a reduced risk for prostate cancer. Overall, these studies suggest only a small potential benefit from lycopene [30,31]. Additionally, these studies have not evaluated the use of lycopene supplements; the benefits of supplements remain unclear.

Teas

Many antioxidant-containing beverages, such as green tea, black tea, and oolong tea, are also popular for preventing cancer. Some observational and clinical research has found that drinking two or more cups of tea daily is associated with a reduced risk for developing ovarian cancer when compared with those who never or seldom consume tea [32,33,34]. Some observational research also suggests that green tea, specifically, may reduce the risk of endometrial cancer when compared with those who never or rarely drink green tea [32]. However, research evaluating these teas for the prevention of other forms of cancer is limited and the results are conflicting.

Other Supplements

Many other natural substances, which are often sold as dietary supplements, are promoted for anti-cancer purposes. In many cases, these substances have shown anti-tumor activity in laboratory research. However, this activity rarely persists when these chemicals are studied in animals, and the vast majority of these chemicals have yet to be adequately studied in humans. Thus, the activity of these chemicals against cancer, either as treatment or prevention, remains mostly hypothetical.

GENERAL DIETARY CONSIDERATIONS

In general, patients should be counselled to follow a healthy diet, which can reduce their risk for a variety of health complications, including, but not limited to, cancer. This healthy diet should generally align with the recommendations found in the U.S. Dietary Guidelines (2020–2025) [35]:

- Following a healthy diet pattern, as appropriate for each age group

- Consumption of nutrient-dense foods and beverages

- Meeting nutrient needs while staying within calorie limits, and

- Limiting the intake of alcoholic beverages, as well as foods and beverages that are higher in added sugars, saturated fats, and sodium

The guidelines clarify that dietary choices should always consider personal preferences, cultural traditions, and budget considerations and should be customized to each individual patient whenever possible [35].

In line with these recommendations, the American Cancer Society specifically recommends that people limit their intake of red and processed meats, sugar-sweetened beverages, and highly processed foods. The organization also emphasizes the importance of consuming nutrient-rich foods, vegetables, fruits, and whole grains [10].

Other dietary components are also periodically suggested for the prevention of cancer. Some of the most common include fiber sources such as oats and barley, as well as "healthy" fats like olive oil and fish oil. While some of these claims are supported (at least in part) by observational research, there is no strong evidence warranting a recommendation to focus on the consumption of these dietary components for cancer reduction. However, these ingredients do provide other health benefits, such as reducing the risk for cardiovascular disease. For this reason, these and other healthy dietary components should be recommended in moderation as part of a healthy diet.

4. OTHER LIFESTYLE INTERVENTIONS

PHYSICAL ACTIVITY

Increased physical activity and exercise is known to reduce the risk for a variety of serious health outcomes and may also reduce the risk for cancer, either directly or indirectly. The Centers for Disease Control and Prevention (CDC) recommends that all adults [36]:

- Obtain 150 to 300 minutes of moderate intensity activity per week, such as brisk walking. Alternatively, this can be replaced with 75 to 150 minutes of vigorous intensity activity, such as hiking, jogging, or running.

- Consider additional activity beyond the recommended 300 minutes

- Participate in muscle strengthening exercises at least two days per week

These guidelines provide alternate recommendations for older adults, pregnant adults, and adults with chronic health conditions or disabilities. Additionally, the guidelines focus on the importance of only participating in safe physical activities that are appropriate to a person's current fitness level. Those who are currently inactive and looking to increase their activity levels should "start low and go slow" [36]. The American Cancer Society reiterates these general recommendations for physical activity and also cautions against sedentary behavior, such as sitting or lying down, for extended durations [10].

Observational research has linked higher physical activity with lower cancer risk; however, most of these studies relied on patients reporting their own historical physical activity levels, which can be unreliable. The link between physical activity and reduced cancer risk has been identified in multiple studies for the following forms of cancer: bladder, breast, colon, endometrial, esophageal, kidney, and gastric [37].

While this link is not entirely understood, multiple mechanisms of action have been hypothesized. For example, increased physical activity can result in [37]:

- Lower levels of sex hormones and growth factors that contribute to the development and progression of certain forms of cancer

- Lower levels of insulin, which can contribute to certain forms of cancer

- Reduced overall inflammation

- Improved immune system function

- Reduced obesity, which has been independently associated with cancer risk

WEIGHT MANAGEMENT

Over the years, it has become increasingly clear that obesity is independently associated with an increased risk of cancer. Obesity is usually identified via body mass index (BMI), an imperfect measure that is calculated using height and weight. Although BMI does not measure body fat directly, it has been moderately correlated with more direct measures of body fat. It is also strongly correlated with specific adverse health outcomes, including development of diabetes, hypertension, heart disease, stroke, and cancer [38].

Classification based on BMI (kg/m^2):

- Underweight: <18.5

- Normal: 18.5–24.9

- Overweight: 25–29.9

- Obese: >30

Evidence Based Practice Recommendation

The American Cancer Society, in recognition that increased body weight is associated with heightened risk of several types of cancers, recommends that individuals keep weight within the healthy range and avoid weight gain in adult life.

https://www.cancer.org/cancer/risk-prevention/diet-physical-activity/acs-guidelines-nutrition-physical-activity-cancer-prevention/guidelines.html

Last Accessed: May 29, 2025

Level of Evidence: Expert Opinion/Consensus Statement

The rate of cancers attributed solely to excess body weight between the years 2011 and 2015 were 4.7% for men and 9.6% for women, according to data analyzed from the U.S. Cancer Statistics database. These rates varied by cancer type, with the highest body weight-associated cancer rate occurring with liver and gallbladder cancers, endometrial cancer, and esophageal cancer [39]. A separate study estimated that excess body weight accounted for 4% of all cancers across the world in 2012 [40,41]. The reasons for this correlation are unclear; however, the hypotheses mirror those for physical activity and include elevated levels of sex hormones, insulin, and inflammation [41].

Because obesity is also associated with many other serious health outcomes, such as diabetes and heart disease, all patients should be counseled on weight management. Modest weight loss of 5% to 10% in total body weight has been shown to result in measurable health benefits, including a reduced risk for chronic diseases. Although it is not clear how much weight loss is necessary to reduce a person's risk of cancer, weight loss (and particularly sustained weight loss) at a younger age is anticipated to reduce cancer risk. Research into this topic is currently ongoing, with a focus on people who have undergone bariatric surgery leading to maintained weight loss [41].

SUN EXPOSURE

Exposure to ultraviolet (UV) light is known to cause early aging of the skin, as well as damage that can ultimately lead to the development of skin cancer. As noted previously, the most commonly diagnosed cancers in the United States are actually skin cancers, albeit nonmalignant ones. These are basal cell carcinoma and squamous cell carcinoma. Melanoma, a less common form of skin cancer, can also be caused by exposure to UV light and represents a greater risk due to its ability to metastasize.

Evidence Based Practice Recommendation

The U.S. Preventive Services Task Force recommends counseling young adults, adolescents, children, and parents of young children about minimizing exposure to UV radiation for persons 6 months to 24 years of age with fair skin types to reduce their risk of skin cancer.

https://jamanetwork.com/journals/jama/fullarticle/2675556

Last Accessed: May 29, 2025

Strength of Recommendation: B (There is high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial.)

Patients should be counseled to avoid unnecessary exposure to UV radiation, which can come from excessive time spent outdoors or via tanning beds. Regardless of age or skin tone, all patients should take steps to protect their skin from sunlight. Some helpful recommendations include [42]:

- Wearing a hat with a wide brim to shade the face, neck, and ears

- Wearing long sleeves and long pants, particularly those with dark, woven fabrics

- Using sunscreen products, particularly those with a sun protection factor (SPF) of at least 15; many professional organizations recommend an SPF of at least 30

It can be easy to forget that UV rays can penetrate through windows and clouds and are also reflected off of a variety of surfaces, including water, snow, ice, and sand. This means that even patients who are protected from direct exposure to the sun (for example, via an umbrella while sitting on the beach) may still be subject to reflected UV light. Additionally, patients should be reminded that it is important to reapply sunscreen periodically throughout the day [42].

The FDA provides further advice on selecting a sunscreen product. This advice recommends the use of only broad-spectrum sunscreens, which provide protection against both types of UV light (UVA and UVB) and have been shown to reduce the risk of skin cancer. Additionally, the FDA reminds consumers that all sunscreens will eventually wash off and should not be considered waterproof or sweatproof [43].

TOBACCO USE

Tobacco use is the leading, established cause of cancer and cancer mortality. People who use tobacco products via any method (including smoking and chewing), as well as those who are exposed to tobacco smoke in their environments, are at an increased risk of cancer. Although most people associate smoking with lung cancer, it has actually been shown to increase the risk of many other forms of cancer as well, including cancer of the larynx, mouth, esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon, and cervix [44]. Use of tobacco snuff or chewing tobacco has been shown to increase the risk of mouth, esophagus, and pancreatic cancers [45].

Patients should be counseled to fully avoid the use of tobacco, in any form. Patients who are already using tobacco should be counseled on methods that may be helpful for quitting. There is currently no known safe amount of tobacco use via any method of administration [44]. Similarly, there is no safe amount of secondhand smoke from tobacco. Whenever possible, people should strive to spend their time in a smoke-free environment, and to provide a smoke-free environment to the people around them [46].

The good news is that people who quit smoking will see a slow reversal in their cancer risk levels over time, ultimately reducing their risk of cancer and increasing their life expectancy.

E-cigarettes, also referred to as e-cigs, vaporizers, or vapes, have become popular tobacco alternatives. These products contain pure nicotine (the addictive chemical found in cigarettes) instead of tobacco. When they were first introduced to the market, it was believed that the use of nicotine in place of tobacco would reduce the risk for cancer. However, it is now known that the vapor produced by these products contains other chemicals as well [47].

Due to the relative newness of these products, their long-term impact on cancer risk is not fully understood. Unfortunately, since these products tend to contain a variety of chemicals that have the potential to pose health risks, it is anticipated that long-term health risks may be identified in the future. Additionally, acute health risks have already occurred with these products, including multiple reports of e-cigarette or vaping product use-associated lung injury (EVALI) in 2019 [48]. Recommend caution with the use of e-cigarettes, and ensure that patients are aware of the unknowns.

5. CONCLUSION

Cancer fear and methods of cancer prevention remain prevalent in the public conversation. This has led to an array of claims regarding lifestyle choices (and products) that may help to reduce a person's cancer risk. Unfortunately, due to the many factors contributing to the development of cancer, no person can guarantee an avoidance of cancer regardless of how many preventive measures are taken.

All patients should be evaluated for appropriate cancer screening and should be encouraged to participate in this screening. Reassure patients that cancer screening is a valuable and proven method for reducing cancer-related mortality, and that cancer-related mortality is on the decline.

Cancer screening discussions also serve as an opportunity to discuss preventive strategies. Considering the stress and anxiety that some people may feel in their efforts to "prevent cancer," it is important to counsel patients on the available evidence of benefit—or lack thereof—with these measures, as well as their risks, time commitments, and costs. These considerations will help to reveal the relative value of a specific strategy for a given person and situation, ideally minimizing the use of strategies that may reduce quality of life or overall healthfulness without a reasonable likelihood for benefit.

Tobacco cessation, reduced sun exposure, and limited alcohol intake are strong, evidence-based forms of cancer prevention that should be recommended for all patients. Weight management, with a focus on avoiding obesity and increasing physical activity, is understood to reduce not only the risk of cancer, but also the risk of various other health complications, including cardiovascular disease. Similarly, all patients should be encouraged to consume a well-rounded, nutrient-rich diet, as this is known to offer a wide range of health benefits.

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Evidence-Based Practice Recommendations Citations

1. American Cancer Society. American Cancer Society Guideline for Diet and Physical Activity. Available at https://www.cancer.org/cancer/risk-prevention/diet-physical-activity/acs-guidelines-nutrition-physical-activity-cancer-prevention/guidelines.html. Last accessed May 29, 2025.

2. U.S. Preventive Services Task Force, Grossman DC, Curry SJ, et al. Behavioral counseling to prevent skin cancer: U.S. Preventive Services Task Force recommendation statement. JAMA. 2018;319(11):1134-1142. Available at https://jamanetwork.com/journals/jama/fullarticle/2675556. Last accessed May 29, 2025.