Risk factors for breast cancer development in patients with borderline breast lesions: a retrospective analysis of our outpatient facility

Introduction: Women affected by benign or borderline lesions will undergo a follow-up which includes both regular, usually yearly, clinical examinations and imaging repetition. The present study aims to determine how many women with a previous diagnosis of breast lesion of uncertain significance develop breast cancer during follow-up and to assess their risk factors. Materials and Methods: This retrospective study included women followed up in the present surgical outpatient facility who underwent a diagnosis of breast lesion of uncertain malignant potential (classified equal or greater than B3 or equal or greater than C3) between January 2003 and June 2014. Main outcomes were the occurrence of breast cancer during follow up and the analysis of possible risk factors for breast cancer development. Results: Among 513 included women, 15 developed breast cancer during the follow up for a borderline breast lesion. The cumulative incidence of new breast cancer diagnosis among women with a previous histological or cytological diagnosis of breast lesion of uncertain malignant potential was 4.3% (95% CI, 1.9-6.6%) at seven years of follow up. Furthermore, the presence of atypical ductal hyperplasia (ADH) and lobular intraepithelial neoplasia (LIN) in the surgical excision specimen, as well as the coexistence of hypothyroidism, resulted to be significant risk factors for new breast cancer development among these patients. Conclusions: Due to the great heterogeneity of benign breast disease, further studies are required to better define its risk to evolve into breast cancer, and consequently to optimize their follow up and management in order to reduce over-treatment of low-risk patients, while improving breast cancer diagnosis among high-risk women.