Faculty Bibliography

To investigate whether parental occupation, especially during the 12 month period before birth, could be responsible for elevated rates of testicular cancer in young men, we used data from a case-control study of 223 cases and 212 controls conducted in the Washington, DC area. For all histologic types of testicular cancer combined, no significant associations were found for specific occupations, nor for the broad occupational categories of professional, other white collar, or blue collar workers. However, for cases with seminomas, excess risks were seen for those with parents employed in the following occupations: mothers in health-related occupations, O.R. = 4.6 (1.1-19.1), and fathers working in automobile service stations, O.R. = 4.0 (0.6-24.5), manufacturing industries, O.R. = 2.2 (1.0-4.2), and aircraft production and maintenance, O.R. = 5.3 (0.7-24.1). Although these findings for seminoma are intriguing, they do not explain the increase of testicular cancer in young men

A case-control study of 271 testicular cancer cases aged 18-42, including 60 seminomas and 206 other germinal cell tumours, and 259 controls was carried out to study the association between occupation and testicular cancer risk. Study subjects were identified at three medical centres, two of which treat military personnel. Controls were men diagnosed with a cancer other than of the genital tract. Associations were identified between professional employment (administrators, teachers and other professionals) and risk for testicular seminoma, OR = 2.8 (95% Cl: 1.4-5.4) and between employment in production work and risk for other germinal cell tumours, OR = 1.8 (95% Cl: 1.1-2.7). No specific occupations within these broad groups were responsible for observed increases. Self-reported exposure to microwave and other radio waves was associated with an excess risk for both seminomas and other germinal cell tumours. However, an assessment of radio wave exposure based on job title did not support this finding. Although testicular cancer has been increasing in recent decades among young males, occupational factors did not appear to account for a substantial proportion of testicular cancer occurrence in the population studied

Over 30 epidemiologic studies have evaluated cancer risks associated with formaldehyde exposure. Excesses were reported for several sites, leukemia and cancers of the nasal cavities, nasopharynx, lung, and brain generating the greatest interest. The excesses of leukemia and brain and colon cancer found among professionals may not be related to formaldehyde exposure, since similar excesses were not observed among industrial workers. Inconsistencies among and within studies impede assigning formaldehyde a convincing causal role for the excesses of lung cancer found among industrial workers. A causal role for formaldehyde is the most probable for cancers of the nasopharynx and, to a less extent, the nasal cavities. Evidence of exposure-response relationships, the fact that direct contact with formaldehyde may occur at these upper respiratory sites, and the consistency of these findings with experimental studies make this assumption highly probable

In a case-control study, we tested the hypothesis that the genetically determined ability to metabolize debrisoquine is related to risk of lung cancer. Overall, individuals who were extensive metabolizers of debrisoquine were at significantly greater risk of lung cancer than those who were poor or intermediate metabolizers (odds ratio = 6.1; 95% confidence interval = 2.2-17.1). In this study, case patients had lung cancer, and control subjects had either chronic obstructive pulmonary disease or cancers other than lung cancer. Results were adjusted for age, race, asbestos exposure, and smoking. Both black and white individuals who were extensive metabolizers of debrisoquine were at significantly increased risk after similar adjustment (for blacks, odds ratio = 4.5, 95% confidence interval = 1.1-18.1; for whites, odds ratio = 10.2, 95% confidence interval = 2.0-51.4). Significantly increased risk of lung cancer was also present for individuals who were extensive metabolizers when subjects with chronic obstructive pulmonary disease or other cancers were considered separately. These data confirm that the ability to metabolize debrisoquine is a major determinant of susceptibility to lung cancer. Evaluation of the marker in other case-control settings, further exploration of racial differences, and the prospective evaluation of this marker in subgroups at high risk of lung cancer are areas worthy of further study

The relation between serum vitamin A measurements made at baseline examination (1971-1975) and subsequent development of prostate cancer was examined in the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study (1981-1984). The analytic cohort consisted of 2440 men 50 years of age or older who were followed for a median of 10 years. A total of 84 men developed prostate cancer. The mean level of serum vitamin A was significantly lower (P less than 0.01) in prostate cancer cases than in noncases. Considered as a continuous variable or in quartiles, a statistically significant (P less than 0.005 or P less than 0.02, respectively) trend was observed for increased risk of prostate cancer with decreasing levels of serum vitamin A. Adjusted for age and race, men in the lowest quartile had a relative risk of 2.2 (95% confidence intervals, 1.1, 4.3) compared to those in the highest quartile. The elevated risk of prostate cancer associated with the lowest quartile of serum vitamin A levels did not attenuate with increasing time between blood drawing and diagnosis, suggesting that metabolic effects of early disease are an unlikely explanation of these results. The inverse association between serum vitamin A and prostate cancer incidence was independent of age at examination and several other possible confounding variables. This is the first prospective study of serum vitamin A and prostate cancer to include a large (84) number of cases

The mortality risk of iron ore (haematite) miners between 1970 and 1982 was investigated in a retrospective cohort study of workers from two mines, Longyan and Taochong, in China. The cohort was limited to men and consisted of 5406 underground miners and 1038 unexposed surface workers. Among the 490 underground miners who died, 205 (42%) died of silicosis and silicotuberculosis and 98 (20%) of cancer, including 29 cases (5.9%) of lung cancer. The study found an excess risk of non-malignant respiratory disease and of lung cancer among haematite miners. The standardised mortality ratio for lung cancer compared with nationwide male population rates was significantly raised (SMR = 3.7), especially for those miners who were first employed underground before mechanical ventilation and wet drilling were introduced (SMR = 4.8); with jobs involving heavy exposure to dust, radon, and radon daughters (SMR = 4.2); with a history of silicosis (SMR = 5.3); and with silicotuberculosis (SMR = 6.6). No excess risk of lung cancer was observed in unexposed workers (SMR = 1.2). Among current smokers, the risk of lung cancer increased with the level of exposure to dust. The mortality from all cancer, stomach, liver, and oesophageal cancer was not raised among underground miners. An excess risk of lung cancer among underground mine workers which could not be attributed solely to tobacco use was associated with working conditions underground, especially with exposure to dust and radon gas and with the presence of non-malignant respiratory disease. Because of an overlap of exposures to dust and radon daughters, the independent effects of these factors could not be evaluated

A case-control study on prostatic cancer was conducted in Kyoto, Japan, from 1981-1984, including 100 patients with prostatic cancer (PC) and age, hospital, and date-of-admission matched controls of benign prostatic hyperplasia (BPH) patients and general hospital patients. Analysis of several sexual factors obtained through a self-administered questionnaire revealed the following observations: 1) cancer patients had fewer sex partners before marriage (relative risk, RR = 0.35; 95% confidence interval: 0.13-0.93) than the hospital controls; 2) they had more vigorous sexual activities in the third (RR = 2.89; 1.01-8.28) and fourth decades of life (RR = 2.26: 1.03-4.95) than hospital controls, but no significantly different sexual activities from controls in other decades; 3) they had less frequent orgasms (RR = 2.55; 1.11-5.83) than BPH controls or (RR = 4.96: 1.78-13.9) hospital controls, and sexual intercourse appeared to be less satisfactory (RR = 2.08: 1.05-4.13) than that of hospital controls; and 4) they had less frequent episodes of sexually transmitted diseases (RR = 0.36: 0.16-0.83) than BPH controls. Marital status, fertility, ejaculation, masturbation, nocturnal emission, contraceptive use, and wife's episodes of sexually transmitted disease were not linked to prostatic cancer risk

The causes of mortality of 3,649 white and 397 non-white male U.S. embalmers and funeral directors, who had died between 1975 and 1985, were examined in a proportional mortality study. Non-significant excesses were found for malignancies of the buccal cavity and pharynx (PMR = 120) and for nasopharyngeal cancer (PMR = 216). No sinonasal cancers were observed, while 1.7 were expected. A statistically significant excess of colon cancer (PMR = 127) was found and a non-significant excess of brain and other CNS cancer was noted among whites only (PMR = 123). Statistically significant excesses of malignancies of the lymphatic and hematopoietic systems were found in whites (PMR = 131) and non-whites (PMR = 241). Myeloid leukemia (PMR = 157) and leukemia of other and unspecified cell types (PMR = 228) were in excess, while no excess of lymphatic leukemia was noted. Elevations in risk were also found for non-Hodgkin's lymphoma, polycythemia vera, and myelofibrosis. Non-whites showed a marked excess of multiple myeloma (PMR = 369). Chronic nephritis was in excess among whites (PMR = 215) and non-whites (PMR = 257). No excess of cirrhosis of the liver was found. Excesses of malignancies of the lymphatic and hematopoietic systems could not be directly related to job held in the funeral industry. Further case-control studies are planned to rule out the possibility that the observed associations are artifactual, by assessing the association between specific work practices and disease risk

Cause-specific mortality of 2,510 persons treated before 1965 by nasopharyngeal radium irradiation (average exposure, 1,200 mg/min), followed to 1985, was compared to that of 2,199 nonexposed comparison subjects. No excess was found for the exposed group in overall mortality, cancer mortality, or in mortality of cancer of specific sites. A marginal excess (p = .07) of malignancies of the lymphatic and hematopoietic system was noted in exposed males only. Only one brain cancer (0.2 per 10(4) person-years) was identified in the exposed group, and two (10.3 per 10(4) person-years) in the nonexposed group