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 aetiologicalrelationships from the Asia-Pacific region. Therefore, a collaborative study was conducted involving over half amillion subjects from 33 cohort studies in the region. Age-adjusted death rates from colorectal cancer, over anaverage 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 deathfrom 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 nosignificant dose-response relationship was discerned (p >0.05). Other significant (p <0.05) risk factors werebody mass index and lack of physical activity. There was no significant effect on colorectal cancer mortality foralcohol consumption, waist circumference, fasting blood glucose or diabetes, although the latter conferred anotable 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 couldprovide opportunities for novel preventive and therapeutic intervention.