A case-control study of factors affecting the development of renal cell cancer.

A hospital-based case-control study was conducted between 1977 and 1983 of 189 men and 78 women with renal cell carcinoma at 18 hospital centers in six US cities and an equal number of controls matched on the basis of hospital, sex, race, age (+/- 5 years), and time of admission (+/- 12 months). Quetelet index (weight/height2) was found to be associated with renal cell cancer in both men and women. Crude odds ratios (ORs) for individuals in the upper tertile of the Quetelet index distribution (28 or more) were calculated to be 2.7 (95% confidence interval (CI) = 1.5-5.9) among men and 2.4 (95% CI = 1.2-6.8) among women compared to the lowest tertile. This relationship was found to be independent of the effects of cigarette smoking, chewing tobacco use, and decaffeinated coffee consumption. The use of chewing tobacco among men was positively associated with disease (OR = 4.0; 95% CI = 1.2-12.9). This was due primarily to a significant interaction between chewing tobacco use and cumulative cigarette smoking. The fitted odds ratio for persons who chewed tobacco and had 30 pack-years of cigarette smoke exposure, compared to never users of either tobacco product, was 26.0 (95% CI = 4.4-153.0) after adjusting for Quetelet index and decaffeinated coffee use. The odds ratio for decaffeinated coffee consumption among men and women combined was 1.9 (95% CI = 1.0-3.8) after controlling for other risk factors. A consistent dose-response was not found, however, by number of cups of decaffeinated coffee consumed per day. Those drinking 1-2 cups had an odds ratio of 2.0 while those drinking 3 cups or more per day had an odds ratio of 1.3, thus casting doubt on a causal interpretation of the finding. Alcohol drinkers had a lower, although not significantly different, rate of renal cell cancer than did never drinkers when the data were examined separately by sex. However, combining the data for both sexes yielded a crude odds ratio of 0.6 (95% CI = 0.4-1.0) for this association. There was no independent effect of tobacco smoking on the odds ratio for renal cell cancer. No significant differences between cases and controls were found for either the amount or duration of artificial sweetener use or the lifetime consumption of saccharin. Beverages such as caffeinated coffee, soft drinks, and tea, in addition to physical activity and occupation, were unrelated to the occurrence of disease.