Science Spotlight

Colon cancer survival: another reason to be physically active

From the Phipps Group, Public Health Sciences Division

Colorectal cancer survival rates have been increasing in recent decades yet it is the third leading cause of cancer-related death in the United States. Understanding factors that influence survival of colorectal cancer patients may have a substantial public health impact. Dr. Amanda Phipps and colleagues in the Public Health Sciences Division recently published a paper in Cancer Epidemiology, Biomarkers & Prevention that reveals a beneficial association of moderate physical activity with survival in stage III colon cancer patients.

For their study, the authors analyzed data collected from participants of a multicenter phase III randomized adjuvant chemotherapy clinical trial. All patients enrolled in the parent trial had resected stage III colon cancer, and the median follow-up time was about 7 years. Included in the current study were nearly 2,000 participants who completed a physical activity questionnaire after colon resection but prior to starting chemotherapy. To capture physical activity levels, the questionnaire asked participants about their physical activity during a typical day and how often during their free time they took part in any physical activity. The participants were also asked about activity intensity—the frequency in which they participated in moderate or vigorous physical activity. Participants who reported engaging in no physical activity or only one time per month were grouped together. The associations of physical activity with time-to-recurrence, overall survival, and disease-free survival primary outcomes were then assessed.

Graphical representation of association of daily physical activity with colon cancer outcomes
Association of daily physical activity with colon cancer outcomes including overall survival (left) and disease-free survival (right). Image provided by Dr. Amanda Phipps

Overall, the participants in the study were generally physically active, with 75% indicating that they engaged in physical activity at least several times per month. Participation in physical activity during free time more than once a month, as compared to once a month or less, was associated with significantly improved overall survival and disease-free survival (see Figure). Moderate, but not vigorous, intensity physical activity more than once a month was also associated with better survival. Usual daily activity level (none, mild, moderate, or heavy) was not associated with any of the outcomes. There were also no associations between time-to-recurrence with physical activity level or intensity.

Limitations of some of the previous research evaluating the relationship between physical activity and colorectal cancer survival include potential confounders, as described by Dr. Phipps, “Prior studies had also reported a favorable relationship between physical activity and colon cancer outcomes, but there have always been concerns about treatment effects and confounding – specifically, that physically active patients might have better prognosis because they have better access to care.” However, the design of the new study was able to address these concerns, “By conducting our study within a clinical trial population, we were able to eliminate that source of bias,” said Dr. Phipps.

The finding that even relatively modest levels of physical activity around the time of colon cancer diagnosis are associated with better survival outcomes are consistent with previous findings that reported beneficial effects of physical activity on colon cancer outcomes. Furthermore, these results are supportive of the current recommendation that cancer survivors regularly participate physical activity, with at least 150 minutes of activity per week.

This research was supported by the National Cancer Institute.

Phipps AI, Shi Q, Zemla TJ, Dotan E, Gill S, Goldberg RM, Hardikar S, Jahagirdar B, Limburg PJ, Newcomb PA, Shields A, Sinicrope FA, Sargent DJ, Alberts SR. 2018. Physical activity and outcomes in patients with stage III colon cancer: A correlative analysis of phase III trial NCCTG N0147 (Alliance). Cancer Epidemiology, Biomarkers & Prevention. doi:10.1158/1055-9965.EPI-17-0769.