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 [1.314.2]) 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 cavity were 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, avoidance of 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.

Pregnancy ; Tobacco ; Tobacco, Smokeless ; Tobacco Smoke Pollution ; Cigarette Smoking ; Rectum ; Smokers ; Smoking ; Breast Cancer 3 ; Breast Neoplasms ; Mouth Neoplasms ; Health Personnel ; Colon

Polymorphisms in metabolic genes have been shown to modulate susceptibility to oral cavity cancer. Cases (n=176) and controls (n=317) from the Filipino population were genotyped for selected polymorphisms in CYP1A1, GSTM1, GSTP1, GSTT1, NAT1 and NAT2. Medical and diet histories, occupational exposure and demographic data were also collected for all subjects. The CYP1A1m1/m1 genotype is protective against oral cancer, while being homozygous for the GSTP1 c.313G genotype and heterozygous for the NAT1*10 homozygotes and non-homozygotes for the CYP1A1 m1 allele. The risk from heterozygosity for the NAT1*10 allele was limited to subjects who were not homozygous for the GSTP1 c.313G genotype remained a significant oral cancer risk modifier, together with environmental variables, the homozygous GSTP1 c.313G genotype remained a significant oral cancer risk modifier, together with environmental risk factors, such as smoking, passive smoking, inverted smoking and tobacco chewing, and environmental protective factors, i.e. moderate consumption of fish sauce (patis) and shrimp paste (bagoong). The GSTP1 c.313G polymorphism increases susceptibility for oral cavity cancer in the Filipino population.

Cyp1a1 Protein, Human ; Cytochrome P-450 Cyp1a1 ; Tobacco Smoke Pollution ; Alleles ; Smoking ; Homozygote ; Ointments ; Protective Factors ; Glutathione Transferase ; Mouth Neoplasms ; Diet