Uterine myomas and smoking. Results from an Italian study

OBJECTIVE: To evaluate the relationship between smoking and uterine myomas requiring surgery. STUDY DESIGN: We conducted a case-control study in Milan between 1986 and 1992. Cases were 476 patients under 55 years of age with histologically confirmed myomas. Controls were 1,283 women admitted to the hospital for a spectrum of-acute, other-than-gynecologic, hormonal or neoplastic conditions (30% trauma, 25% nontraumatic orthopedic conditions, 25% surgical, 20% other miscellaneous). RESULTS: Cases were less frequently current smokers (22%) than controls (32%). In comparison with never smokers, the multivariate relative risk (RR) for myomas was 0.5 (95% confidence interval [CI], 0.4-0.7) in smokers. Ex-smokers were 10% of cases versus 7% of controls (RR 1.2, 95% CI 0.9-1.8). No clear trend in risk was observed with the number of cigarettes smoked per day or duration of smoking and risk of fibroids. The estimated RRs were largely consistent when separate analyses were performed in strata of body weight. CONCLUSION: Current smoking seems to reduce the risk of myomas.