A population-based case-control study was carried out in three geographic areas of the U.S. to examine reasons for differences in incidence between Blacks and Whites for a variety of cancers. Analyses are underway using attributable risk modeling to look at social class in four cancer sites, esophagus, multiple myeloma, pancreas, and prostate. The analyses will attempt to determine how much of the risk from social class is due to tobacco use and how much is due to other factors. Results were reported showing no association between multiple myeloma and total number of reported diagnostic X-rays of any type. Investigators 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. Although increased folate intake was associated with decreased oral cancer risk, the finding was due almost entirely to folate intake from fruit, 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 genotype had a non-significantly lower risk, and risk patterns tended to differ by level of folate, methionine, alcohol intake and smoking. After controlling for alcohol and tobacco use, there was an increased risk of oral and pharyngeal cancer for subjects reporting a first-degree relative with the same disease. This suggests a heritable component to oral and pharyngeal cancer or shared environmental factors other than alcohol and tobacco. In a case-control study of prostate cancer in Shanghai, China, investigators reported lower risk of disease among men with greater intake of allium vegetables, in particular with greater intake of garlic and scallions. These associations were independent of the intake of other foods and of total calories. An analysis examined the effects of the timing of occupational asbestos exposure to lung cancer using pooled data from two large case-control studies conducted in Germany. Odds ratios (OR) and 95% confidence intervals (CI) showed an increased risk with duration of asbestos exposure (OR=1.8, 95% CI=1.2-2.7 and OR=2.4, 95% CI=1.7-3.4 for subjects working 3 to 7 years and 8 or more, respectively, in jobs with potential asbestos exposure compared to never-exposed). The OR decreased significantly with time since last exposure to about one-half after more than 20 years since exposure ceased. A spline weight function model revealed that the risk effect reached a maximum 10 to 15 years prior to interview, then declined. The relationship between mortality and protracted low-dose radiation exposure was evaluated in a large cohort of U.S. radiation technologists. Work history variables were analyzed using external and internal comparisons to account for secular trends. Results suggest increased risk for breast cancer, leukemia, and circulatory disease, especially stroke, for subjects working in early years when radiation exposure was likely to be high. No consistent increase of risk was found for multiple myeloma or lymphoma. In a hospital-based case-control study of 159 cases of cancer of the testis and 136 controls, investigators found no association between dietary phytoestrogens and testicular cancer risk in young men. An extended mortality follow-up of a cohort of formaldehyde workers was provided information on the potential effect of formaldehyde on lung cancer risk. Multivariate analyses including exposure to formaldehyde and several other agents revealed no relationship with lung cancer risk, but did reveal an excess risk with malignancies of the hematopoietic system. Investigators conducted a hospital-based case-control study of invasive cutaneous melanoma. There were 718 cases and 945 controls matched by gender, race, age, and geographic area. Results showed that a 10% increase in annual UVB flux was associated with a 19% increase in individual odds of melanoma for men and 16% for women. The effect of UVB intensity during the ages 0-19 is as important as UVB intensity during the adult ages. Total time outdoors has an important effect on the risk of melanoma. Another melanoma investigation evaluated objective measurements of constitutive skin color and ultraviolet light sensitivity in relation to risk of invasive cutaneous melanoma in a study in Italy of 183 cases and 179 controls. Constitutive skin color and skin ultraviolet light sensitivity were assessed by colorimetry and minimal erythema dose (MED), respectively. ORs of melanoma increased by a factor of 1.20 (95% CI=1.12-1.30) for each unit of skin brightness and by a factor of 1.24 (95% CI=1.07-1.43) per 10 mJ/cm2 of MED. These associations were largely independent of phenotypic or sun-related characteristics, but were modified by sun exposure. Increased risk of melanoma was observed only among subjects with the highest levels of sun exposure. Another analysis of these data resulted in a chart which linked melanoma risk associated with combinations of factors and could be used to identify subjects from a Mediterranean population who would most benefit from preventive measures. Finally, in these same data, it was also found that glucocorticoid-based therapy appeared to be protective against melanoma incidence, with the degree of protection increased with treatment duration, but not the reason for treatment. Controls from a population-based case-control study of breast cancer in Asian women living in California and Hawaii, in which migration history was associated with a 6-fold risk gradient that paralleled historical differences in incidence rates, were used to evaluate migration history and levels of endogenous hormones. Plasma was measured for estrone, estradiol, estrone sulfate, androstenedione, testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate, progesterone and sex hormone-binding globulin. Levels of estrogens and sex hormone-binding globulin did not differ significantly between Asian-born women and western-born women of Asian decent in either pre- or postmenopausal women. Among postmenopausal women, androgens tended to be highest among the least westernized women, and declined as the degree of westernization increased. The relationship between 45 common agricultural pesticides and prostate cancer incidence was evaluated in the Agricultural Heath Study, a large prospective cohort study of private (farmers) and commercial pesticide applicators. The standardized incidence ratio (SIR) for prostate cancer (SIR=1.14, 95% CI=1.05-1.24) was significantly elevated compared to the male populations of Iowa and North Carolina. Factor analysis identified a pesticide use pattern characterized by use of chlorinated pesticides among applicators over 50 years of age, that was significantly associated with prostate cancer risk. Methyl bromide, a widely used halogenated fumigant, was also associated with an excess risk. Several other pesticides showed a significantly increased risk of prostate cancer among study subjects with a family history of prostate cancer but not among those with no family history. Investigators developed two quantitative exposure measures to estimate long-term chemical-specific pesticide exposures, based on data from an enrollment questionnaire and a take-home questionnaire. A `general' algorithm was based on the enrollment questionnaire and used four basic variables (i.e. mixing status, application method, equipment repair status and use of personal protective equipment), as well as measurement data from the published pesticide exposure literature. A second algorithm was based on variables in the general algorithm plus additional information from the take-home questionnaire, including types of mixing system used (i.e., enclosed or open), having a tractor with enclosed cab and/or charcoal filter, frequency of washing equipment after application, frequency of replacing old gloves, personal hygiene and changing clothes after a spill. Weighting factors were applied in both algorithms based on measurement data from the published pesticide exposure literature and professional judgment. Investigators conducted a 40-year mortality follow-up study of Korean war navy technicians with potential exposure to high-intensity radar. Compared to US White men, deaths from all causes and from all cancers were below expected values. There was no evidence of increased brain cancer in all subjects or in those technicians in high-exposure occupations. The analysis indicated that radar exposure had little effect on mortality in this cohort of navy technicians. Investigators have examined the pattern of multiple occurrences of four radiation-related neoplasms in a radiation-exposed cohort of 2795 patients receiving conventional radiation treatments for benign conditions in the head and neck area when they were children. There were 350 thyroid cancers, 108 benign and malignant salivary tumors, 87 neural tumors, and 70 cases of hyperparathyroidism. There were 492 individuals (17.6%) with single tumors, and 60 individuals (2.1%) with multiple tumors. An analysis showed that the excess concordance of neoplasms could be explained by known risk factors, such as sex, age and dose, thereby suggesting that susceptibility factors did not play a role in the development of multiple tumors. Analyses of hormone replacement therapy for menopausal symptoms were conducted in a cohort of women from the Breast Cancer Detection Demonstration Project who developed ovarian cancer between 1980 and 1998. Based on 329 cases of ovarian cancer, ever-use of estrogen-only was significantly associated with increased risk. Neither estrogen-progestin-only use nor estrogen-progestin use following estrogen-only use was associated with ovarian cancer. Increasing duration of estrogen-only use was associated with a 7% (95% CI= 2%-13%) increase in relative risk per year of estrogen-only use. There was no association between duration of estrogen-progestin use and ovarian cancer. Investigators reported results from a case-control study of incident lung cancer in a rural area of China, including 886 cases and 1,659 frequency matched controls, for residential radon exposure, exposure to environmental tobacco smoke, previous diagnosis of lung disease, air pollution, and exposure to cooking oil fumes. Time-weighted average radon concentrations were 230.4 Bq/m3 for cases and 222.2 Bq/m3 for controls. Risk increased with increasing radon level. The excess odds ratio at 100 Bq/m3 was 0.19 (95% CI= 0.05-0.47) for all subjects, and 0.31 (95% CI=0.10-0.81) for subjects with 100% coverage of the exposure interval. Adjusting for exposure uncertainties increased estimates 50 percent. Lung cancer risk was also associated with previous diagnosis of pulmonary tuberculosis (OR=2.1, 95% CI=1.4-3.1) and chronic bronchitis/emphysema (OR=1.4, 95% CI=1.1-1.8). Non-significant associations were observed for a previous diagnosis of asthma (OR=1.4, 95% CI=0.9-2.1) and pneumonia (OR=1.5, 95% CI=1.0-2.3). The OR for lung cancer associated with burning coal compared to biomass was 1.29 (95% CI=1.0-1.6) and increased with percent of time coal was used over the past 30 years (p=0.02). Among 200 female and 33 male lung cancer cases and 407 female and 114 male controls who never smoked. The OR for ever-exposed to environmental tobacco smoke was 1.19 (95% CI=0.7-2.0), with a significant trend (p<0.05) with increasing exposure. Among 233 incident, female lung cancer cases and 459 controls the OR associated with ever-use of rapeseed oil, alone or in combination with linseed oil, was 1.67 (95% CI=1.0-2.5), compared to use of linseed oil alone. ORs for stir-frying with either linseed or rapeseed oil 15-29, 30, and >31 times per month were 1.96, 1.73, and 2.24, respectively (trend, p=0.03), relative to a lower frequency of stir-frying. Lung cancer risks also increased with total number of years cooking (trend, p<0.09).
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