An epidemiologic case-control study of breast cancer and exposure to hair dyes.

An epidemiologic case-control study of 1617 patients with a primary breast cancer and 1617 control subjects was conducted to test the hypothesis that use of hair dyes is related to breast cancer. No overall association was observed between breast cancer risk and "ever use" of hair dyes (odds ratio, 1.04; 95% confidence interval, 0.90 to 1.21), age when hair dye use started and age when it stopped, duration of hair dye use (years), types of hair dyes used, and estimated lifetime number of individual applications. The current data set also failed to show an increased risk for breast cancer in women who had been diagnosed with benign breast disease and were exposed to hair dyes.

Cigarette smoking and breast cancer.

An epidemiological case-control study was conducted in New York State, with 1617 primary breast cancer patients and an equal number of controls, to examine the relationship between cigarette smoking and breast cancer. Results showed no overall association between ever smokers versus never smokers and breast cancer risk (odds ratio [OR] = 1.03, 95% confidence interval [CI]: 0.90-1.19), nor was there any dose response trend observed with increased levels of smoking. In addition, no association was found with risk and age started smoking, age stopped smoking, amount smoked or total years smoked. Controlling for previously identified risk factors for breast cancer in the analysis did not significantly alter these relationships. Previous studies have found a difference in menopausal age among smokers compared to nonsmokers. The mean menopausal age was only slightly lower in smokers than in never smokers for both cases and controls. Breast cancer risk was observed to be close to unity for premenopausal women (OR = 0.97, 95% CI: 0.74-1.34) and postmenopausal women (OR = 1.06, 95% CI: 0.91-1.26). A recent study suggested breast cancer risk was more strongly related to starting smoking at a young age among women who smoked at least 25 or more cigarettes per day in the most recent year of smoking. This hypothesis was not supported by these data.

An epidemiological case-control study of breast cancer and alcohol consumption.

A case-control study of breast cancer and alcohol consumption was conducted with 1617 patients diagnosed with a primary cancer of the breast between 1982 and 1984 in 18 New York State counties. For each case, one control, matched for year of birth and county of residence, was selected from the driver's license files of the New York State Department of Motor Vehicles. Breast cancer risk was shown to increase as daily consumption of alcohol increased, with a risk of 1.37 (95% Cl = 1.07, 1.75) observed among women who consumed 15 or more grams of alcohol per day. Breast cancer risk did not appear to be related to the total number of years a woman drank or to be restricted to specific types of alcoholic beverages. The data suggest that this may be higher in women who began drinking at a later age. The increased risk associated with alcohol consumption, observed in the current study, persisted within strata of various breast cancer risk factors.