Several pre-diagnosis lifestyle factors, including physical activity level, smoking status, and waist circumference, may predict survival with stage I to III colorectal cancer (CRC), according to research published in the International Journal of Cancer.1

The Melbourne Collaborative Cohort Study (MCCS) previously showed that physical activity prior to CRC diagnosis is linked to CRC-specific survival. This article includes 11 further years of follow-up to MCCS as well as data regarding microsatellite instability (MSI), disease subtype, and BRAF/KRAS status.

Of 1227 enrolled patients with CRC, 724 (467 colon/257 rectal) were included in survival analyses. During a median follow-up from diagnosis of 9 years, 339 patients died, including 170 CRC-specific deaths.

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Although no overall association was found between cigarette smoking and CRC-specific survival, former smokers who quit at least 10 years prior to evaluation had a hazard ratio (HR) for CRC-specific death of 1.92. Smokers with BRAF­-mutated disease also had an HR for death of 1.82.

Patients with a large waist-circumference had worse CRC-specific survival (HR for death per 10 cm increase, 1.25); there was, however, no clear association between body mass index and survival.

Patients who exercised prior to diagnosis with stage II disease had improved CRC-specific survival (HR, 0.25), though no association was found between exercise and stage I or stage III disease.

No survival associations were noted for alcohol intake or MSI status.

The authors concluded that “smoking, exercise and obesity are not only risk factors for CRC, but are associated with survival after diagnosis. Future research is necessary to determine whether exercising, losing weight and smoking cessation after CRC diagnosis affect survival, and to examine underlying molecular pathological mechanisms underpinning these associations.”


  1. Jayasekara H, English DR, Haydon A, et al. Associations of alcohol intake, smoking, physical activity and obesity with survival following colorectal cancer diagnosis by stage, anatomic site and tumor molecular subtype. Int J Cancer. 2017 Sep 16. doi: 10.1002/ijc.31049 [Epub ahead of print]