Krystle Zuniga, PhD, RD, CSO, LD
Despite a wealth of information on the relationship between modifiable lifestyle factors and cancer incidence, there is a limited understanding of their implications for outcomes post-cancer diagnosis. Currently, cancer survivors are advised to follow the same lifestyle recommendations for cancer prevention.
Over the last year, the World Cancer Research Fund’s (WCRF) Global Cancer Update Program has released comprehensive reports on post-diagnosis lifestyle factors in relation to breast cancer and colorectal cancer outcomes.1,2 These comprehensive literature reviews synthesized and evaluated the quality and strength of the growing body of evidence to provide recommendations on lifestyle factors post-cancer diagnosis.
Post-Breast Cancer Diagnosis
In 2023, the WCRF published the report on postdiagnosis physical activity, dietary factors, supplement use, and breast cancer outcomes.1 The evidence that healthy dietary and lifestyle patterns reduce the risk of all-cause mortality was graded as limited-suggestive. Healthy diets were described as plant-forward diets with minimal consumption of red and processed meat, processed foods, and sugary beverages. A whole foods-based diet is also high in fiber, as dietary fiber is found in a variety of plant foods including whole grains, fruits, vegetables, beans, nuts, and seeds. The evidence that dietary fiber intake reduces risk of all-cause mortality was graded as limited-suggestive. Every 10 grams-per-day increase in fiber was associated with a 10% lower risk of all-cause mortality.
Numerous studies have refuted the misconception that soy is detrimental to breast cancer survivors, yet misinformation persists. Original concerns were that the isoflavones in soy are phytoestrogens that may stimulate growth of estrogen-sensitive tumors. Not only is soy safe for breast cancer survivors but the report graded the evidence as limited-suggestive that isoflavones from soy foods reduce the risk of all-cause mortality, breast cancer mortality, and breast cancer recurrence.
Vitamin D, a fat-soluble vitamin, plays crucial roles beyond bone health, including immune support, cell differentiation, and insulin sensitivity. Limited-suggestive evidence shows that maintaining adequate serum vitamin D levels may reduce the risk of all-cause mortality and breast cancer-specific mortality. Providers may consider testing serum 25-hydroxyvitamin D levels to ensure sufficiency, as levels below 20 ng/mL are associated with increased risk of poorer clinical outcomes.
Exercise is increasingly recognized as a potent adjunct therapy as numerous studies have demonstrated the benefits for combating fatigue and improved quality of life, mental health, and physical function.3 The WCRF report provided support for the protective effects of engaging in regular physical activity for survival and recurrence. Graded as limited-suggestive evidence, higher levels of recreational physical activity lower risk of all-cause mortality, breast cancer-specific mortality, and breast cancer recurrence with higher levels of recreational physical activity.
Post-Colorectal Cancer Diagnosis
In early May, the 2024 WCRF report on colorectal cancer prognosis underscored the role of lifestyle factors in shaping outcomes post-diagnosis.2
Like the findings in breast cancer survivors, the evidence that healthy dietary and lifestyle patterns reduce the risk of all-cause mortality was graded as limited-suggestive. Further, the report determined there is limited-suggestive evidence that unhealthy dietary patterns increase the risk of all-cause mortality.
Post-diagnosis, the evidence that whole grains reduce the risk of all-cause mortality was graded as limited-suggestive. One serving a day, which is equivalent to a 1-oz slice of whole grain bread or a ½ cup of cooked whole grains, reduces the risk by 10%. Total coffee, caffeinated coffee, and decaffeinated coffee were all determined to reduce the risk of all-cause mortality. In contrast, sugary drinks increase the risk of all-cause mortality, with just 1 serving a day associated with a 20% higher risk. The evidence for both coffee and sugary drinks was judged as limited-suggestive.
A comparison between individuals with the highest and lowest levels of physical activity revealed a 33% lower risk of all-cause mortality and a 20% lower risk of colorectal cancer recurrence. The evidence indicating that recreational physical activity can decrease the risk of both all-cause mortality and colorectal cancer recurrence was graded as limited-suggestive.
Conclusion
While data on post-diagnosis lifestyle factors and outcomes for other cancer types are limited, the consistent evidence regarding the benefits of physical activity and a healthy dietary pattern for prevention and post-diagnosis suggests potential benefits for other cancer types as well.
Many patients want to know how they can optimize their outcomes. From mitigating disease recurrence to enhancing overall survival rates, these reports from the WCRF support that dietary modifications and regular physical activity may positively influence prognosis. Providers can recommend that survivors adopt healthy lifestyle habits following a cancer diagnosis including a dietary pattern rich in plant foods and limited in processed foods and sugary drinks, and adequate physical activity. Oncology providers should offer referrals to registered dietitians, physical therapists, and/or certified cancer exercise trainers that can create a personalized approach to lifestyle interventions and improve adherence to lifestyle interventions.
Current and emerging research underscore the need for healthcare providers to promote lifestyle interventions as essential components of cancer care and survivorship programs.
Krystle Zuniga, PhD, RD, CSO, LD, is a board-certified specialist in oncology nutrition and owner of Cancer Nutrition HQ in Austin, TX.
References
- Tsilidis, K. K., Cariolou, M., Becerra-Tomás, N., Balducci, K., Vieira, R., Abar, L., Aune, D., Markozannes, G., Nanu, N., Greenwood, D. C., Giovannucci, E. L., Gunter, M. J., Jackson, A. A., Kampman, E., Lund, V., Allen, K., Brockton, N. T., Croker, H., Katsikioti, D., McGinley-Gieser, D., … Chan, D. S. M. (2023). Postdiagnosis body fatness, recreational physical activity, dietary factors and breast cancer prognosis: Global Cancer Update Programme (CUP Global) summary of evidence grading. International journal of cancer, 152(4), 635–644. https://doi.org/10.1002/ijc.34320
- Tsilidis, K. K., Markozannes, G., Becerra-Tomás, N., Cariolou, M., Balducci, K., Vieira, R., Kiss, S., Aune, D., Greenwood, D. C., Dossus, L., González-Gil, E. M., Gunter, M. J., Allen, K., Brockton, N. T., Croker, H., Gordon-Dseagu, V. L., Mitrou, P., Musuwo, N., Wiseman, M. J., Copson, E., … Chan, D. S. M. (2024). Post-diagnosis adiposity, physical activity, sedentary behaviour, dietary factors, supplement use and colorectal cancer prognosis: Global Cancer Update Programme (CUP Global) summary of evidence grading. International journal of cancer, 155(3), 471–485. https://doi.org/10.1002/ijc.34904
- Campbell, K. L., Winters-Stone, K. M., Wiskemann, J., May, A. M., Schwartz, A. L., Courneya, K. S., Zucker, D. S., Matthews, C. E., Ligibel, J. A., Gerber, L. H., Morris, G. S., Patel, A. V., Hue, T. F., Perna, F. M., & Schmitz, K. H. (2019). Exercise Guidelines for Cancer Survivors: Consensus Statement from International Multidisciplinary Roundtable. Medicine and science in sports and exercise, 51(11), 2375–2390. https://doi.org/10.1249/MSS.0000000000002116
