Effect of physical activity and body size on survival after diagnosis with colorectal cancer

Abstract

Background: Physical inactivity and obesity increase the risk of colorectal cancer but little is known about whether they influence prognosis after diagnosis. Methods: Incident cases of colorectal cancer were identified among participants of the Melbourne Collaborative Cohort Study, a prospective cohort study of 41 528 Australians recruited from 1990 to 1994. Participants diagnosed with their first colorectal cancer between recruitment and 1 August 2002 were eligible. At the time of study entry, body measurements were taken and participants were interviewed about their physical activity. Information on tumour site and stage, treatments given, recurrences, and deaths were obtained from systematic review of the medical records. Results: A total of 526 cases of colorectal cancer were identified. Median follow up among survivors was 5.5 years, and 208 deaths had occurred, including 181 from colorectal cancer. After adjusting for age, sex, and tumour stage, exercisers had an improved disease specific survival (hazard ratio 0.73 (95% confidence interval (CI) 0.54-1.00)). The benefit of exercise was largely confined to stage II-III tumours (hazard ratio 0.49 (95% CI 0.30-0.79)). Increasing per cent body fat resulted in an increase in disease specific deaths (hazard ratio 1.33 per 10 kg (95% CI 1.04-1.71)). Similarly, increasing waist circumference reduced disease specific survival (hazard ratio 1.20 per 10 cm (95% CI 1.05-1.37)). Conclusions: Increased central adiposity and a lack of regular physical activity prior to the diagnosis of colorectal cancer is associated with poorer overall and disease specific survival.

The Impact of Body Mass Index and Physical Activity on Mortality among Patients with Colorectal Cancer in Queensland, Australia

“…When we repeated our analysis restricting to stage III participants only, the significant association between weight loss and risk of mortality remained. PA Previous studies examining the relationship between being more physically active before diagnosis of CRC and survival found marginal (26) or no effects (8,9). However, studies of postdiagnosis PA have shown that being more physically active after diagnosis reduces the risk of allcause and disease-specific mortality in stages I to III CRC patients (7,8) and reduced risk of cancer recurrence and overall mortality in stage III CRC patients (7).…”

Association Between Body Size and Colorectal Adenoma Recurrence

“…The evidence for obesity as a common risk factor in a number of human diseases, including colorectal cancer, has led to the hypothesis that the metabolic changes associated with chronic overeating and sedentary behaviors have a role in development of many pathologies 8 . The majority of epidemiologic studies support a role for obesity as a risk factor for colorectal adenomas [9][10][11][12][13][14][15][16][17][18] , cancers 12,[19][20][21][22][23][24][25][26][27][28][29][30] ; and colon cancer mortality 31,32 . These observations suggest a continuous action of the adverse effects of obesity along the adenoma to carcinoma continuum, starting early in colon tumorigenesis.…”

Health benefits of physical activity: the evidence

“…Other studies have shown similar associations. 75,76 There are ongoing efforts to try to understand the mechanism of this survival effect, including the effects of exercise on the effectiveness of chemotherapy.…”