Influence of physical activity on recurrence and survival of colorectal cancer patients: A meta-analysis.
1583 Background: Colorectal cancer (CRC) predominates in developed countries among sedentary populations. A meta-analysis (MA) showed that physical activity (PA) decreased the incidence of new cases of CRC. The impact of PA on recurrence and mortality of non-metastatic CRC patients is still controversial. Methods: We performed a literature-based meta-analysis of all published observational studies, using the following keywords (colorectal cancer, physical activity, survival) in PubMed and EMBASE. We searched for a dedicated MA in the Cochrane Library (none found). We cross-checked all references. Pre- and post-diagnostic PA levels were assessed with MET (Metabolic Equivalent Task). Usually, high PA levels corresponded to > 17 MET hours/week. Overall survival (OS) and cancer-specific survival (CSS) were assessed by means of Hazard Ratios (HRs) with their 95 % Confidence Interval (CI). We pooled adjusted HRs since the variables of adjustment were almost identical between studies (age, sex, BMI, tobacco use, alcohol and red meat consumptions ). By convention, when higher PA levels were associated to an improved survival compared with lower PA levels, HRs for detrimental events were < 1. We used EasyMA software. We used fixed effect model whenever possible and random effect model only in case of between-study heterogeneity. Results: Eight studies (11298 participants) published from 2006 to 2013 met the inclusion criteria, representing 3110 males and 3710 females, 3072 colon and 1318 rectum cancers. Mean age was 67 years (range 21-82 years). HR CSS for post-diagnostic PA (higher PA level vs. lower) was 0.61 (CI: 0.44-0.86; random effect model). The corresponding HR for OS was 0.62 (CI: 0.54-0.71). HR CSS for pre-diagnostic PA was 0.80 (CI: 0.69-0.92). The corresponding HR for OS was 0.74 (CI: 0.63-0.86). Conclusions: This MA is the first to show that higher PA levels are associated with a better CSS, suggesting that sustained PA should be advised for non-metastatic CRC patients. OS also significantly improved, not surprisingly since PA should reduce risk of cardio-vascular events. These findings should be tempered by the rather small number of studies included.