Impact of surgical variables on residual glandular tissue in risk-reducing mastectomies: Results of a retrospective monocentric study from a center of the German consortium for hereditary breast and ovarian cancer.

PURPOSE: Residual glandular tissue (RGT) after risk reducing mastectomy (RRME) is associated with a risk of developing breast cancer for women with a familial predisposition. We aim to examine various surgery-related variables to make risk more easily assessable and to aid in decision-making. MATERIALS AND METHODS: Pre- and postoperative breast MRI scans from 2006 to 2021 of patients with proven pathogenic mutation were included. The postoperative remaining skin flap was recorded using distance measurements at 8 equally distributed clockwise points and retromamillary. Each breast was volumetrized, as well as existing RGT. Patient-related covariates were further recorded and their influence on RGT was investigated uni- and multivariately. RESULTS: 81 patients (49 with BRCA1, 24 with BRCA2, 9 with other mutations), who were on average 39 years old, had 117 breasts analyzed. The mean follow-up was 71 months. In multivariate analysis, the independent variable skin flap thickness had a positive effect (p ≤ 0.01), while surgeon experience negatively affected RGT (p ≤ 0.05). The incision type was found to impact RGT as well, with nipple-sparing mastectomy (NSM) with inframammary fold incision leading to more RGT (p ≤ 0.01 - p ≤ 0.05), and skin-sparing mastectomy (SSM) with an inverted T incision leading to less (p ≤ 0.01). CONCLUSION: Different surgical variables have an impact on postoperative RGT, which is an important tool to quantify the risk of developing breast cancer after RRME. In order to effectively consider these variables in future preoperative/intraoperative management, they must be carefully taken into account.

Factors Influencing Residual Glandular Breast Tissue after Risk-Reducing Mastectomy in Genetically Predisposed Individuals Detected by MRI Mammography.

PURPOSE: This study seeks to evaluate MR imaging morphological factors and other covariates that influence the presence of residual glandular tissue after risk-reducing mastectomy in patients with a familial predisposition. METHODS: We analyzed women of a high-risk collective with pathogenic mutation (BRCA1 (n = 49), BRCA2 (n = 24), or further mutation (n = 9)). A total of 117 breasts were analyzed, 63 left and 54 right, from a cohort of 81 patients, who were on average 40 years old. The mean follow-up was 63 months (range 12-180 months, SD = 39.67). Retrospective analysis of MR imaging data from 2006-2022 of patients of a high-risk collective (all carriers of a pathogenic mutation) with contralateral (RRCM) or bilateral risk-reducing mastectomy (RRBM) was performed. In the image data the remaining skin flap thickness by distance measurements at eight equally distributed, clockwise points and the retromamillary area, as well as by volumetry of each breast, was elected. Residual glandular tissue was also volumetrized. In addition, patient-related covariates were recorded and their influence on postoperative residual glandular tissue and skin flap thickness was analyzed by uni- and multivariate regressions. RESULTS: A significant association with postoperative residual glandular tissue was shown in multivariate analysis for the independent variables breast density, skin flap mean, and surgical method (all p-values < 0.01). A negatively significant association could be seen for the variables preoperative breast volume (p-values < 0.01) and surgeon experience (most p-values < 0.05-<0.1). CONCLUSION: Postoperative residual glandular tissue is an important tool for quantifying the risk of developing breast cancer after risk-reducing mastectomy. Different effects on residual glandular tissue were shown for the independent variables breast density, skin flap, surgical method, preoperative breast volume, and surgeon experience, so these should be considered in future surgical procedures preoperatively as well as postoperatively. Breast MRI has proven to be a suitable method to analyze the skin flap as well as the RGT.