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The work history information from a population-based case-control study conducted in Puerto Rico was analyzed using a job exposure matrix to investigate the relationship between occupational exposures and cancers of the oral cavity or pharynx. After adjustment for age, alcohol, smoking, and residence in a logistic model, the risk for cancer of the oral cavity, but not the pharynx, was significantly elevated among farm workers in the sugarcane industry (OR = 4.4, 95% CI = 1.4-13.6). An exposure-response trend was seen for cumulative exposure to solvents, with an OR = 3.2 (95% CI = 0.8-12.6) in the highest exposure category. The overall contribution to the risk of cancer of the oral cavity or pharynx associated with occupational exposures in Puerto Rico appears to be small, however, the elevated risks were seen among sugarcane farmers and subjects with high cumulative exposure to solvents.

BACKGROUND Use of alcohol and tobacco are the major risk factors for cancers of the oral cavity and pharynx in most of the world. A heritable component to oral carcinoma risk also has been suggested, although only limited data are available on familial aggregation of this disease. METHODS A population-based case–control study of 342 subjects with carcinomas of the oral cavity and pharynx (oral carcinoma) and 521 controls was conducted in Puerto Rico. The relation between family history of carcinomas of the oral cavity, the upper aerodigestive tract (UADT), and other selected sites with risk of oral carcinoma was explored using logistic regression modeling techniques. RESULTS Risk of oral carcinoma was elevated for subjects reporting a first-degree relative with carcinoma of the oral cavity (odds ratio [OR], 2.5; 95% confidence interval [CI], 0.8–8.0) or any UADT carcinoma (OR, 2.6; 95% CI, 1.4–4.8). The increased risk associated with family history of UADT carcinoma tended to be greatest for subjects with known risk factors (i.e., heavy consumption of alcohol and/or tobacco and infrequent intake of raw fruits and vegetables) and with oral carcinoma diagnoses at ages younger than 65 years. CONCLUSIONS These findings are consistent with a heritable component to oral carcinoma, although shared lifestyle risk factors may be partially involved. Cancer 2001;92:2102–8. © 2001 American Cancer Society.

Objectives: To determine if the risk of cancers of the mouth and pharynx is associated with mouthwash use in Puerto Rico, an area of relatively high risk. Methods: Interviews were conducted with 342 cases of oral and pharyngeal cancer registered in Puerto Rico and diagnosed between 1992 and 1995 and with 521 population-based controls regarding mouthwash use and other factors. Mouthwash-related risks were estimated using unconditional logistic regression controlling for potential confounders. Results: The adjusted odds ratio associated with using mouthwash with an alcohol content of 25% or greater was 1.0. Risks were not higher with greater frequency, years of use, or lifetime mouthwash exposure. Among tobacco and alcohol abstainers the odds ratio associated with mouthwash use was 2.8 (CI = 0.8–9.9), in contrast to 0.8 (CI = 0.4–1.7) and 0.9 (CI = 0.6–1.3) among those with light and heavy cigarette smoking/alcohol drinking behaviors, respectively. Conclusions: There was no overall increased risk of oral cancer associated with mouthwash use. An elevated, but not statistically significant, risk was observed among the small number of subjects who neither smoked cigarettes nor drank alcohol, among whom an effect of alcohol-containing mouthwash would be most likely evident. Our findings indicate the need to clarify the mechanisms of oral carcinogenesis, including the possible role of alcohol-containing mouthwash.

Objectives: To determine risk for oral cancer in Puerto Rico associated with use of alcohol and tobacco. Methods: In Puerto Rico, alcohol and tobacco use were compared among nonsalivary gland cancers of the mouth and pharynx (n=342), cancers of major and minor salivary glands (n=25) and 521 population-based controls. Results: Alcohol (usual use, Ptrend

Genetic polymorphisms resulting in variation in metabolism of tobacco carcinogens may influence oral cancer risk. In a population-based case-control study in Puerto Rico, genotypes of CYP1A1, GSTM1, and GSTT1 were determined by a PCR-based method for 132 oral cancer patients and 143 control subjects. Genotype-associated risks were estimated by logistic regression. The null variant of GSTM1 was associated with a marginally significant decrease in oral cancer risk [odds ratio (OR) = 0.6, 95% confidence interval (CI) = 0.3-1.0, and P for trend = 0.09]. Risks increased with increasing cigarette use among subjects with the GSTM1-present genotype (P for trend

Alcohol consumption is a major risk factor for cancers of the mouth and pharynx (oral cancer), but the differential risks by beverage type are unclear. In this 1992-1995 study, the authors examined oral cancer risk in Puerto Rico, comparing alcohol intake among 286 male cases aged 21-79 years and 417 population-based male controls, frequency matched by age. Heavy consumers of liquor (>/=43 drinks per week) had strongly increased risks of oral cancer (odds ratio = 6.4, 95% confidence interval: 2.4, 16.8); beer/wine showed only modest effects. Among liquor drinkers, risks were consistently greater for those who drank straight (undiluted) liquor than for those who usually drank mixed (diluted) liquor (odds ratio = 4.0, 95% confidence interval: 2.4, 6.7). Risks associated with combined exposure to tobacco were also more pronounced when subjects drank liquor straight. The elevated risks associated with drinking homemade rum were similar to those for other types of liquor. These results suggest that alcohol concentration is a risk factor for oral cancer independent of the total quantity of alcohol consumed.

We examined the relationships between folate and methionine intake, serum homocysteine levels (as a biomarker for folate metabolism), and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism genotype and risk of oral cancer in a population-based, case-control study in Puerto Rico. Structured questionnaires were used to collect information on demographic factors, usual adult diet, and tobacco and alcohol use. Oral epithelial cells and blood samples were collected from a subset of subjects. Analyses were conducted by logistic regression, adjusting for age, sex, lifetime smoking and lifetime alcohol intake, with the following numbers of cases/controls, respectively: dietary data (341/521); MTHFR genotype (148/149); and homocysteine (60/90). Although increased folate intake was associated with decreased oral cancer risk [adjusted odds ratio (OR) in highest vs. lowest quartile = 0.6, 95% confidence interval (CI): 0.4, 1.0, P(trend) = 0.05)], this finding was due almost entirely to folate intake from fruit (adjusted OR = 0.4, 95% CI: 0.2, 0.6; P(trend) = 0.0001), whereas other dietary folate sources showed no clear association. Methionine intake and serum homocysteine levels were not associated with oral cancer risk. Subjects with the MTHFR C677T homozygous variant (TT) genotype had a nonsignificantly lower risk, and risk patterns tended to differ by level of folate, methionine, alcohol intake and smoking, although the power to detect significant associations in subgroups of these variables was low. Risks for oral cancer are not folate specific; preventive recommendations for this disease should emphasize the importance of a healthy diet, including substantial intake of fruits.