Pancreatic cancer among workers processing synthetic resins.

A nested case-control study was conducted to investigate whether an excess of pancreatic cancer, identified in a cohort mortality study with follow-up from 1946 through 1988, was associated with potential workplace exposures at a New Jersey plastics manufacturing and research and development facility. The study population included 28 male pancreatic cancer cases and 140 randomly selected controls, matched on year of birth and at risk (alive) at the time of the case death. Using plant work history records, department assignments for the two groups were compared according to duration and time since first assignment. Workers assigned to a work area that processed vinyl resins and polyethylene (PE) were shown to be at increased risk. Men assigned more than 16 years to this department had a significantly increased risk ratio of 7.15 (95% confidence intervals [CI]: 1.28-40.1). No excess was seen with shorter duration assignments. Seven of the nine cases began working in this area in the 1940s. Average latency was 32 years, and all but three cases worked 20 years or more in this unit. Over the study period, significant exposure-related process changes occurred, in addition to the use of numerous chemical additives. Although vinyl and PE processing operations could not be analyzed separately, the pancreatic cancer excess is more likely to be related to vinyl processing. Identification of a causative agent or combination of agents would require investigations with more detailed exposure information.

Beta-carotene and animal fats and their relationship to prostate cancer risk. A case-control study.

A case-control study of 371 prostate cancer patients and comparable control subjects admitted to Roswell Park Memorial Institute (RPMI), Buffalo, New York, was conducted. Data were obtained from routine epidemiologic questionnaires administered to all patients on admission. An index of beta-carotene intake was computed based on the vitamin A activity of 27 fruits and vegetables included in a food frequency checklist. A similar measure of fat intake from meats was computed based on nine meats included in the checklist. Intake frequencies of common and alcoholic beverages also were studied. A significant age-adjusted and residence-adjusted protective effect for high levels of beta-carotene intake was observed (relative risk [RR], 0.60; 95% confidence interval [CI], 0.37 to 0.99). This effect was evident particularly among men 68 years of age and younger (RR, 0.30; 95% CI, 0.13 to 0.66), but not among subjects older than 68 years of age. A trend toward increased risk for fat intake was not significant. However, the reported usual consumption of high-fat milk was associated with increased risk (RR, 1.92; 95% CI, 1.05 to 3.50). A greater reported frequency of whole milk intake was similarly associated with increased risk. Men who reported drinking three or more glasses of whole milk daily had an RR of 2.49 (95% CI, 1.27 to 4.87), compared with men who reported never drinking whole milk. When these findings are evaluated in the context of other recent studies, the weight of the evidence appears to favor the hypothesis that animal fat intake is related to increased risk of prostate cancer.

Epidemiologic evidence of perinatal influence in the etiology of adult cancers.

Using data from 5489 cancer patients and 2647 patients without cancer we investigated whether parental age at the birth of the patient or the patient's rank within his sibship was related to the risk of cancer during adulthood. An increase of 10 years in maternal age was associated with an increase of 24% for the incidence of breast cancer (odds ratio = 1.24%; 95% CI = 1.09-1.41); the corresponding increase for paternal age was 19% (odds ratio = 1.19; 95% CI = 1.07-1.33). There was some evidence that the age of each parent may make an independent contribution to the risk of breast cancer. For certain types of genito-urinary cancers, the risk was higher when the parents were relatively young at the birth of the patient. These cancers included tumors arising in the prostate (odds ratios = 0.71 and 0.55 for maternal and paternal ages, respectively), testis (odds ratios = 0.57 and 0.52), penis (odds ratios = 0.37 and 0.45), kidney (odds ratios = 0.66 and 0.60), and bladder (odds ratio = 0.79 and 0.85). The associations for cancer of the prostate and bladder were stronger among patients who were diagnosed at a relatively young age. No statistically significant effects were found for birth order relative to adult cancers. The authors conclude that environmental factors that affect the parents or that operate in the perinatal period may have stronger influences on the incidence of adult cancers than have been previously recognized.

Similarity between trans fat and saturated fat in the modification of rat mammary carcinogenesis.

Commercial hydrogenation of vegetable oils results in the introduction of trans fatty acids. In the present study, we have investigated the effect of feeding a fat which contained approximately 38% trans isomers (designated trans fat) on the induction of mammary tumors by dimethylbenz(a)anthracene in rats. The corresponding control fat (designated cis fat), which had a similar fatty acid composition, consisted of only cis isomers. Since both the trans and cis fats were rather saturated, a comparison was also made between these 2 types of fat and corn oil, which contains about 60% linoleic acid (C18:2). Each fat was present in the diet at 2 levels, 5 and 20% by weight. Although rats fed the 20% trans fat or cis fat diets had a slightly higher tumor incidence and yield than did those on the corresponding 5% fat control diets, the difference was not statistically significant. In contrast, rats fed the 20% corn oil diet developed a much greater number of tumors than did rats fed a diet containing only 5% corn oil. Further analysis of the data showed that diets containing either trans fat or cis fat were much less effective than were the corn oil diets in promoting the development of mammary neoplasia at either the 5 or 20% level. Our results thus suggest that trans fat behaves very much like a saturated fat in the modification of mammary tumorigenesis. A determination of the fatty acid content of the mammary fat pad indicated that its composition generally reflected the dietary fatty acid intake, with the incorporation of trans isomers into the mammary tissue found to be dependent on the quantity of trans fat in the diet.