That confounded P-value.
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Biomedical subjects
Publications and source records attributed to C I Cann.
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To investigate whether the non-alcohol content of distilled alcoholic beverages affects the carcinogenicity of the beverage, we conducted an epidemiologic study of laryngeal and hypopharyngeal cancer. We interviewed 384 cases (or spouses, for deceased cases), and compared their responses with those of 876 controls. We classed distilled liquors as dark or light, a rough division according to content of potentially carcinogenic compounds in the beverages. The relative effect on hypopharyngeal cancer risk was much stronger for those who reported high consumption of dark liquor (relative risk = 4.4, 90% confidence interval = 2.9, 6.8) than for those reporting comparable consumption of light liquor (relative risk = 1.3, 90% CI = 0.8, 2.1). For laryngeal cancer, consumption of dark liquor had a smaller effect, and there was little distinction between the effects of dark and light liquor. The data appear consistent with the theory that the non-alcoholic content of distilled alcoholic beverages is a determinant of cancer risk, and that alcoholic beverages act topically rather than systemically in their carcinogenic action.
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Cohort studies of putative human teratogens can identify the full spectrum of phenotypic effects, including both major malformations and minor anomalies. Cohort studies which include the much more common minor anomalies make it possible to use a relatively small number of exposed and unexposed infants to identify an increase in the frequency of malformations. We evaluated this use of minor anomalies in a cohort study of newborn infants who had been exposed in utero to three putative teratogens: insulin-dependent diabetes mellitus in the mother and the use of the anticonvulsant phenytoin and exogenous sex hormones by the mother. In addition, the reproducibility of identifying minor anomalies was tested by comparing the results of examinations by two independent observers of 444 unexposed infants. The frequency of minor anomalies was increased among infants of diabetic mothers. However, the reproducibility of identifying minor anomalies was poor. We conclude that the examination of teratogen-exposed infants for minor anomalies cannot be used in epidemiologic studies of putative teratogens unless special efforts are made to maximize consistency in the identification of these features.
We examined 4305 white newborn infants for 114 minor physical features and major malformations to evaluate the hypothesis that the presence of three or more minor anomalies is highly predictive of a major malformation. We confirmed that the infant with three or more minor anomalies is at increased risk for a major malformation. However, this risk (19.6%) was much lower than the risk of 90% popularized by Smith and based on the study of Marden et al. (J Pediatr 1964;64:357). Analysis of the findings in the two studies showed that the lower predictive value was probably related to differences in study design. Nevertheless, some minor anomalies remain essential to the early recognition of several serious malformation syndromes.
Epidemiologic investigations have been instrumental in identifying numerous factors associated with the development of cancer. Tobacco and alcohol are unquestionably the major risk factors for squamous cell carcinoma of the head and neck region. Diet appears to play a role in the development of these cancers, as nutritional deficiencies have been found to increase risk. Clinical observation and epidemiologic studies have also identified ionizing radiation as an unequivocal risk factor, although of lesser importance from the public health point of view. Overall, epidemiologic evidence shows that occupational exposures play a minor, though definite, role in the development of head and neck cancer. For sinonasal cancer, however, studies corroborate that occupational exposures are the major determinants of disease.
The authors conducted a case-control study to identify employment-related risk factors for laryngeal cancer. Richmond County, Georgia, and the contiguous counties were chosen as the study area because the 1950-1969 laryngeal cancer mortality rate for white males in Richmond County was almost double the corresponding rate for the entire United States, and because a large proportion of the working population was employed in industries for which excess risk among workers had been reported. All persons with newly diagnosed squamous cell carcinoma of the larynx treated in the area hospitals were identified. Potential controls were selected from patients admitted to these hospitals during the same time period as the cases, excluding those patients admitted for cancer, lung disease, or employment-related disease. Eighty-five control subjects were individually matched to 42 cases for sex, age, area of residence, and smoking and alcohol-drinking history. From lifetime employment histories, laryngeal cancer rate ratios were estimated comparing the incidence rate among subjects who had ever worked in an occupation with the incidence rate among subjects who had never worked in that occupation. Among the 10 occupations in which at least 15 subjects had worked, the authors found rate ratio estimates above 3.0 for farmers, textile processors who separated, filtered or dried textile fibers, and for all laborers and maintenance personnel.
The evidence demonstrating the strong effects of tobacco and alcohol on laryngeal cancer risk is consistent and compelling. Furthermore, investigations indicate that joint exposures to tobacco and alcohol interact to elevate laryngeal cancer risk above what would be expected if these risk factors had merely additive effects. Occupational findings indicate that a few occupational groups may be facing a greater risk of laryngeal cancer from occupational exposures; this increased risk is not entirely due to alcohol drinking and smoking habits. All patients with laryngeal cancer are at higher risk of developing a second primary tumor; therefore, their treatment and follow-up should be judicious.
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