Background: Colorectal cancer (CRC) is one of the most common cancers worldwide. This study aimed toinvestigate the risk factors for colorectal cancer in the Thai population. Materials and
Methods: A cohort studywas carried out in Khon Kaen, Thailand, including 71 cases of histologically confirmed CRC patients among 19,861participants, aged 30-69 years, who were recruited for a cohort study during the period 1990-2001. Participantswere 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 variablescould be shown to be significantly related to the risk of CRC. Although in our sample, CRC was more prevalentamong males, ex-smokers, and those who drank alcohol beverages ≥ 50 gram/day, but we could not demonstratesignificantly associations (HRmale= 1.67, 95% CI, 0.80-3.49, HR ex-smokers = 1.34, 95% CI, 0.52-3.46, andHRalc≥ 50 = 1.08, 95% CI, 0.43-2.71). Individuals within the sample with a family history of cancer, workinghour >8 hours per day, and current-smokers appeared to have decrease risk of CRC, but again these relationshipcould 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 ofenvironmental factors effecting the risk of CRC. There is a need for further research to determine why factorsidentified risk in other populations appear to not be associated with CRC risk in Thais.