Abstract 2172: Physical activity in relation to overall and colorectal cancer specific survival in the Seattle Colon Cancer Family Registry
Authors: Hardikar Sheetal S. , Newcomb Polly A. , Passarelli Michael N. , Campbell Peter T. , Phipps Amanda I. 
Published: May 2015

Abstract
Background
Previous studies have suggested that physical activity is associated with a reduced risk of colon cancer. The association of physical activity with colorectal cancer (CRC) survival, however, is less clear. Studies evaluating the association between post-diagnostic physical activity and CRC survival suggest a favorable survival among those who engage in regular physical activity after diagnosis. However, such studies are limited by the possibility of reverse causality since individuals engaging in regular physical activity after diagnosis may have had a better prognosis to begin with.
Methods
We evaluated the association between pre-diagnostic physical activity and survival, both overall and CRC-specific, within the Seattle Colon Cancer Family Registry (SCCFR), a prospective cohort of persons diagnosed with CRC between 1997 and 2002. All cases completed a risk-factor questionnaire including information on medical history, demographic and lifestyle factors, such as obesity and decade-specific recreational physical activity. Vital status and cause of death was determined through linkage to a regional cancer registry and National Death Index. Tumor markers (BRAF and KRAS mutation status) were evaluated for a subset of cases. Physical activity was summarized as average weekly metabolic equivalent-task hours (MET-h/week). Adjusted hazard ratios (HR) and 95% confidence limits (95%CI) were estimated using Cox regression.
Results
Primary analyses included 1171 persons who self-reported their physical activity status, of whom 471 died (292 deaths attributable to CRC; median follow-up 6.3 years). After adjusting for age at diagnosis, sex, body mass index and smoking status, those who engaged in physical activity had a significantly lower risk of dying from any cause compared to those who did not engage in any physical activity (HR 0.72, 95%CI 0.51-0.99; HR 0.62, 95%CI 0.44-0.87; and HR 0.60, 95%CI 0.43-0.85 for &gt;0-6.4, 6.4-19.2, and &gt;19.2 MET-h/wk, respectively; P for trend=0.035). Results for CRC-specific survival were similar and suggested improved survival among physically active individuals compared to those that were inactive, although no trend was evident (HR 0.81, 95%CI 0.51-1.28; HR 0.72, 95%CI 0.45-1.15; and HR 0.72, 95% CI 0.44-1.14 for &gt;0-6.4, 6.4-19.2, &gt;19.2 MET-h/wk respectively; P for trend= 0.52). Further adjustment for stage at diagnosis or BRAF and KRAS mutation status did not alter the results.
Conclusion
Our results suggest that individuals who are physically active prior to CRC diagnosis experience more favorable survival than those who are inactive. Increased physical activity was also associated with better CRC-specific survival, but this trend was not statistically significant. Continued follow-up of this and other larger cohorts is needed to further clarify the role of physical activity in CRC prognosis.
Citation Format: Sheetal S. Hardikar, Polly A. Newcomb, Michael N. Passarelli, Peter T. Campbell, Amanda I. Phipps. Physical activity in relation to overall and colorectal cancer specific survival in the Seattle Colon Cancer Family Registry. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2172. doi:10.1158/1538-7445.AM2014-2172