Epidemiological Risk Factors for Cancers of the Lung, Breast, Colon-rectum & Oral cavity: A case-control study in the Philippines

Introduction. In the Philippines, lung, breast, colon-rectum, and oral cavity cancers are among the top 10 most common cancers. This study evaluates the risk factors for these cancers among Filipinos. Methods. This age-matched case-control study included incident primary cancers (histologically-diagnosed) of the lung, breast (also matched for sex), colon-rectum and oral cavity. Controls(clinically free and no history of cancer) were obtained from the same tertiary hospitals as the cases. Target sample size was 283 cases and 283 controls per cancer type. Conditional logistic regression was done. Results. Exposure to cigarette/tobacco was a significant risk factor for lung (OR of current smoker compared to non-smoker [95% Confidence Interval]: 3.6 [1.6-7.9]) and oral cavity cancers (2.0 [1.2-3.3]); family history (1st degree) for lung (4.3 [1.3 – 14.2]) and breast cancers (3.0 [1.2-7.5]); every year increase in age at first pregnancy for breast cancer (1.06 [1.02-1.11]). Other risk factors for oral cavitywere passive smoking (2.8 [1.6-5.1]), chewing tobacco (5.2[1.4-19.5]) and inverted cigarette smoking (3.2[1.3-8.1]). Fish sauce (patis) was found to be a protective factor for breast cancer (0.34 [0.22-0.51]) and oral cavity (0.44 [0.25-0.78]) and use of shrimp paste (bagoong) (0.48 [0.27-0.84]) for oral cavity. Conclusion and Recommendations. Except for family history of cancer, the identified risk factors for lung, colon-rectum, and oral cavity cancers are preventable. Proper diet and lifestyle, avoidanceof cigarettes and tobacco, and environmental safety in the workplace are key cancer prevention measures. Public awareness campaign and continuing healthcare provider education must always be part of a cancer prevention program.