Study objective: The purpose of the study was to investigate the possible association between cigarette smoking and benign proliferative epithelial disorders of the breast.
Design: This was a case-control study with two different control groups.
Setting: The study was community based and took place in metropolitan Adelaide, South Australia.
Subjects: 506 biopsy proven cases between 18 and 75 years were identified, of whom 39 could not be approached because of surgeon refusal, 66 would not be interviewed and 18 were untraceable, leaving 383 for inclusion in the study. Controls were 192 women who had had a negative breast biopsy, out of a possible 259 (17 surgeon refusals, 39 interview refusals, 11 untraceable); and a randomly selected group of women matched to the index group for age and area of residence (582 subjects were approached to enrol 383 controls).
Measurements and main results: All breast biopsies were examined by one pathologist and classified using a standard system. Sociodemographic and medical information was collected by trained interviewers using structured questionnaires. Overall, and within menopausal strata, risk of benign proliferative epithelial disease for women who had ever smoked and for current and ex-smokers was similar to that for women who had never smoked. In premenopausal women, using community controls as the comparison group, risk decreased with cigarette-years of exposure, but the trend was not statistically significant. Risk appeared to increase when biopsy controls were used. There was no trend in the association when examined by degree of cytological atypia.
Conclusions: The data suggest that cigarette smoking is not related to the risk of benign proliferative epithelial breast disease.