Abstract SY08-01: Does exercise or fitness deter cancer progression after diagnosis
Authors: Chan June M. 
Published: April 2024

In the U.S., 42% of cancer cases and 45% of cancer deaths are estimated to be attributable to modifiable factors, including tobacco use. Among women, the combination of excess body weight, poor diet, low physical activity, and alcohol consumption contributed to 22.4% of cases, ahead of tobacco (14.8%), due to prevalence of lifestyle behavior-related cancers in women (e.g. breast). Among men, 24% were due to tobacco, and 13.9% due to obesity, diet, physical activity, and alcohol. Evidence increasingly supports a role of these factors for improving cancer progression and death outcomes among cancer survivors. For example, healthy (e.g. Mediterranean) or unhealthy (e.g. “Western”) dietary patterns are associated with cancer progression or death among individuals diagnosed with colorectal, breast and/or prostate cancers (Rock, CA J Clin, 2022). For example, among 1101 men and women with stage III colon cancer enrolled in the CALGB adjuvant chemotherapy trial, those with a high vs low “Western” dietary pattern (high in meat, fat, refined grains and dessert) had 3.25 times higher risk of recurrence and death (Meyerhardt, JAMA, 2007). Long-term follow up of the Women’s Health Initiative trial participants indicates persistent reduction in deaths after breast cancer, among women randomized to the low fat/high fruit, vegetables and grains intervention compared to usual diet control (Chlebowski, J Clin Onc, 2020).

Studies similarly suggest that physical activity after diagnosis of cancer is associated with a reduced risk all cause and cancer death. Evidence has accumulated such that the 2018 Physical Activity Guidelines for Americans recommended that physical activity after diagnosis is beneficial to reduce cancer death among those with breast, colorectal, and prostate cancer (U.S. Dept. of Health & Human Services, 2018). More recently, in a pan-cancer study of more than 11,000 people with 18 different types of cancer, exercise consistent with guidelines was linked to a 25% reduced hazard of death (95% confidence interval (CI) 0.70-0.80) and a 21% reduced hazard of cancer death (95% CI, 0.72 to 0.88); exercise according to guidelines was defined as moderate-intensity exercise ≥4 days per week, with sessions averaging ≥30 minutes and/or strenuous-intensity exercise ≥2 days per week, with sessions averaging ≥20 minutes) (Lavery JA et al, JCO 2023).

There is also accumulating evidence from studies that examined the combination of multiple lifestyle factors, which indicate the combined benefits of healthy diet, regular physical activity, and weight control in cancer survivors. For example, in the CALGB study, those with a higher American Cancer Society (ACS) cancer prevention guidelines score (based on body mass index, physical activity, and healthy dietary pattern), had a 42% lower risk of death (Van Blarigan, JAMA, 2018). Studies examining combined lifestyle factors scores among men with prostate cancer have observed similar, though not entirely consistent, results for the outcomes of cancer progression and death (Graff RE, Br J Ca 2023; Langlais CS, Br J Ca, 2023). Purported mechanisms for improved outcomes with healthy diet and physical activity include beneficial effects on insulin resistance, inflammation, oxidative stress, and sex hormone pathways. Evidence gaps exist for less common cancers, and more research is needed to understand the impacts of energy balance and body composition on cancer outcomes.

The evidence generated supporting the benefits of physical activity and high diet quality for cancer survivors has resulted in guidelines from multiple national and international organizations, including the American Cancer Society, American College of Sports Medicine, American Institute of Cancer Research/World Cancer Research Foundation, and the American Society of Clinical Oncology. While the publications of these guidelines represent an important milestone, much works remains to see them implemented in practice. Most cancer survivors are not physically active at recommended levels or following dietary recommendations. Programming and services tailored for survivors are needed, but a major challenge is the lack of reimbursement for nutritional and exercise counseling and services in cancer care. While some care settings and community organizations offer exercise and/or nutritional programming and information to people with cancer, this largely relies on institutional funding or philanthropy. Often these programs have limited reach or capacity, and the availability of programs may be particularly limited for cancer patients treated in safety net care settings. In order to address these gaps, wider availability of programs and services as well as clinical workflows to facilitate referral to services by healthcare providers is needed.

In conclusion, evidence is growing that diet and physical activity after a diagnosis of cancer deters cancer-specific and all cause death. Innovative solutions are needed to increase nutritional quality and exercise in cancer survivors, in particular among those who are historically under-served and/or of lower socioeconomic status. Reimbursement for nutrition and exercise counseling for cancer survivors is warranted.

Citation Format: June M. Chan. Does exercise or fitness deter cancer progression after diagnosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr SY08-01.