CLINICAL TRIAL ON CHEMOPROPHYLAXIS OF BREAST CANCER WITH AROMATASE INHIBITOR LETROZOLE IN WOMEN WITH A HIGH RISK OF DEVELOPING BREAST CANCER. PART I: SELECTION OF PATIENTS, THE FREQUENCY OF PRECANCEROUS STATES

In 2004 - 2010, in the Research Institute of Clinical Oncology of the N.N. Blokhin National Medical Research Center of Oncology there was implemented a prospective randomized clinical trial on chemoprophylaxis of breast cancer with letrozole in women with precancerous states of the breast epithelium. The hypothesis of the study supposed letrozole to be capable to eliminate or at least halt the progression of breast precancerous changes, represented by atypical hyperplasia or hyperplasia without atypia. The study included women with a potentially high risk of developing breast cancer: female patients with validated risk factors for the disease or a risk of contralateral breast cancer with a personal history of the disease. The ultimate goal of the examination was to identify patients with morphologically proven precancerous changes in the mammary gland with positive expression of estrogen receptors. To obtain a morphological material, periareolar fine-needle puncture of the mammary gland was performed. The effectiveness of the developed method of sampling happened to be high, allowing the diagnosis in 172 (96.6%) of 178 patients. Hyperplasia without atypia was detected in 69 (38.8%) women, atypical hyperplasia - in 81 (45.5%) patients, in 22 (12.3%) women no pathological changes in the epithelium were detected. The study has failed to be completed due to the slow recruitment of patients. Despite the incompleteness of the study, new data on the prevalence of breast precancerous changes in the postmenopausal women in the Russian population and significant experience in the organization and implementation of studies on chemoprophylaxis of breast cancer have been obtained.