Can Physical Activity Delay Progression in Metastatic Colorectal Cancer?

Increased physical activity did not appear to be related to overall survival among patients diagnosed with metastatic colorectal cancer, according to a study published in the Journal of Clinical Oncology. However, the study did find physical activity had an effect on progression-free survival and risk for certain treatment-related adverse events.

“Although our observational study does not offer evidence for causality, it builds on mounting evidence that demonstrates improved colorectal cancer outcomes with greater physical activity and extends this association to colorectal cancer with metastases,” wrote researchers led by Brendan J. Guercio, MD, of Brigham and Women’s Hospital in Boston. “Although additional studies are needed to confirm these results, our findings support the discussion and recommendation of physical activity in the management of metastatic colorectal cancer.”

To look at this possible association, Guercio and colleagues conducted a prospective study nested in the phase III Cancer and Leukemia Group B (Alliance)/SWOG 80405 trial. The study included 1,218 patients with metastatic colorectal cancer. All patients completed a validated questionnaire reporting average physical activity over the previous 2 months. Using this information, the researchers calculated metabolic equivalent task (MET) hours per week. Patients who experienced progression or died within 60 days of activity assessment were excluded.

 Within this group of patients, 47% had less than 3 MET hours per week, 24% had 3 to 8.9 hours per week, 12% had 9 to 17.9 hours per week, and 17% had 18 or more hours per week.

After a median follow-up of more than 6 years, 1,056 patients had disease progression and 945 died. After adjusting for potential predictors of patient outcome, there was no association between greater physical activity and overall survival. Compared with patients with less than 3 MET hours per week, those with 18 or more had an adjusted hazard ratio for overall survival of 0.85 (P_trend=.06).

Greater physical activity was associated with significantly improved progression-free survival though. Compared with those with less than 3 MET hours per week, patients with 18 or more hours per week had an adjusted hazard ratio of 0.83 (P_trend=.01).

The study also looked at walking duration and risk for all-cause mortality. Although no significant association was found, greater walking duration was associated with progression-free survival in an unadjusted and adjusted analysis.

In addition, compared with patients who engaged in less than 9 MET hours per week, patients engaging in 9 or more had an adjusted hazard ratio for grade 3 or worse treatment-related adverse events of 0.73 (P_trend<.001). 

“Although an association between greater activity and reduced treatment toxicity is novel in the context of mCRC, it is consistent with studies in nonmetastatic malignancies, including randomized trials of exercise in patients with breast cancer that decreased nausea, pain, and improved chemotherapy completion rates,” the researchers wrote.

The researchers noted that reduced physical activity seen among these patients could simply be a marker of poor health and that they were unable to exclude residual confounding by poor health.

“However, our findings are supported by the fact that patients had normal or near-normal performance status,” they noted. “Our findings remained statistically significant after adjusting for weight loss and comorbidities. Nonetheless, randomized clinical trials of physical activity interventions are needed to confirm our findings.”