Risk Factors for Colorectal Cancer in Thailand

Background: Colorectal cancer (CRC) is one of the most common cancers worldwide. This study aimed to investigate the risk factors for colorectal cancer in the Thai population. Materials and Methods: A cohort study was carried out in Khon Kaen, Thailand, including 71 cases of histologically confirmed CRC patients among 19,861 participants, aged 30-69 years, who were recruited for a cohort study during the period 1990-2001. Participants were followed-up until 31 December, 2013. To identify factors associated with the incidence of colorectal cancer, hazard ratios were evaluated using Cox proportional hazard regression. Results: No environmental variables could be shown to be significantly related to the risk of CRC. Although in our sample, CRC was more prevalent among males, ex-smokers, and those who drank alcohol beverages ${\geq}50gram/day$, but we could not demonstrate significantly associations (HRmale= 1.67, 95% CI, 0.80-3.49, HR ex-smokers = 1.34, 95% CI, 0.52-3.46, and HRalc ${\geq}50=1.08$, 95% CI, 0.43-2.71). Individuals within the sample with a family history of cancer, working hour >8 hours per day, and current-smokers appeared to have decrease risk of CRC, but again these relationship could not be shown to be significantly associated (HRfam cancer= 0.96, 95% CI, 0.85-1.09, HRwork>8= 0.84, 95% CI, 0.36-1.93, and HRcurrent-smoker = 0.51, 95% CI, 0.18-1.38). Conclusions: We found no evidence of environmental factors effecting the risk of CRC. There is a need for further research to determine why factors identified risk in other populations appear to not be associated with CRC risk in Thais.