The role of lifestyle risk factors on mortality from colorectal cancer in populations of the Asia pacific region

Although colorectal cancer is one of the leading malignancies worldwide, there are few data on aetiological relationships from the Asia-Pacific region. Therefore, a collaborative study was conducted involving over half a million subjects from 33 cohort studies in the region. Age-adjusted death rates from colorectal cancer, over an average of 6.8 years follow-up, were 12 and 14 per 100,000 person-years among Asian women and men, respectively; corresponding values in Australasia were 31 and 41. Height was strongly associated with death from colorectal cancer: an extra 5cm of height was associated with 10% (95% confidence interval, 3% - 18%) additional risk, after adjustment for other factors. Smoking increased risk by 43% (9% - 88%), although no significant dose-response relationship was discerned (p >0.05). Other significant (p <0.05) risk factors were body mass index and lack of physical activity. There was no significant effect on colorectal cancer mortality for alcohol consumption, waist circumference, fasting blood glucose or diabetes, although the latter conferred a notable 26% additional risk. Height may be a biomarker for some currently unknown genetic, or environmental, risk factors that are related both to skeletal growth and mutanogenesis. Understanding such mechanisms could provide opportunities for novel preventive and therapeutic intervention.