Intracystic epidermal growth factor level is predictive of breast-cancer risk in women with gross cystic disease of the breast

Women affected by gross cystic disease of the breast have an increased risk of breast cancer. We report here the incidence of breast cancer by cyst ty pe and intracystic epidermal growth factor (EGF) concentration. Our retrosp ective study included 504 women who had at least I cyst aspiration between 1985 and 1993, Cyst fluids were processed for electpolyte concentration (n = 378), EGF concentration (n = 347) or both (n = 337), Age-standardized inc idence ratios (SIRs) were estimated using the population of the Genoa Cance r Registry. A multivariate Poisson regression model was used to estimate re lative risks (RRs) when the study groups were compared directly. By June 19 99, 19 invasive breast cancers had developed in the cohort of women. The ag e SIR of breast cancer calculated for the whole cohort was 3.32 (95% confid ence interval 2.00-5.18), The ratio was not affected by age and was only mo derately increased in women with a positive family history of breast cancer and type I cysts (i.e., those with a Na+/K+ ratio <3). However, it was sig nificantly increased in women with high EGF concentrations, Direct comparis ons confirmed that age, cyst type and family history only moderately increa sed the RR, whereas EGF concentration was a strong predictor of risk. Our r esults confirm that women affected by palpable cysts have an increased risk of developing breast cancer and suggest that the risk is higher in women w ith high intracystic EGF concentrations. (C) 2801 Wiley-Liss, Inc.