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

Risk factors for residual fibroglandular breast tissue following a mastectomy - an overview and retrospective cohort study

BACKGROUND

Residual fibroglandular breast tissue (RFGT) following a mastectomy is associated with the remaining of occult breast cancer at the time of mastectomy as well as an increased local recurrence risk thereafter. Despite its oncologic implications, data on measures to prevent RFGT are lacking. Therefore, in a first step knowledge of risk factors for RFGT is of uttermost importance in order to allow identification of patients at risk and subsequently adaption of the surgical treatment and potentially prevention of RFGT a priori.

METHODS

We performed a systematic literature review in PubMed using the MESH terms [residual fibroglandular breast tissue], [residual breast tissue], [mastectomy] and [risk factor] followed by a retrospective data analysis including all patients with a mastectomy treated at the Department of Obstetrics and Gynecology of the Medical University of Vienna, Austria, between 01.01.2015 and 26.02.2020 in order to identify risk factors of RFGT following a mastectomy. The primary aim of the study was to assess a potential difference in RFGT volume between the different types of mastectomy. The secondary objectives of the study were to identify other potential risk factors for RFGT as well as to compare the skin and subcutaneous fat tissue thickness pre- to postoperatively.

RESULTS

Significantly higher RFGT volumes were observed following a nipple-sparing mastectomy (NSM) compared to a skin-sparing mastectomy (SSM) and radical mastectomy (RME) (p < .001). Furthermore, RFGT volume was significantly associated with the variables: reconstruction (p = .012), acellular dermal matrix (ADM) or mesh (p = .031), patient age (p = .022), preoperative fibroglandular tissue (FGT) volume (p = .012) and preoperative whole breast volume (including the skin envelope and nipple-areola-complex) (p = .030). The reduction in the postoperative compared to preoperative skin envelope thickness measured medially and laterally reached statistical significance in the NSM-cohort (medial p < .001, lateral p = .001) and showed a numerical difference in the RME and SSM-cohort.

CONCLUSION

Mastectomy type, reconstruction, ADM or mesh, patient age, preoperative FGT volume and whole breast volume were identified as risk factors for RFGT in univariable analysis. The observed reduction in the post- compared to preoperative skin envelope thickness should be avoided considering the known associated increase in risk for ischemic complications.

A BRILLIANT-BRCA study: residual breast tissue after mastectomy and reconstruction

INTRODUCTION

Different types of mastectomies leave different amounts of residual breast tissue. The significance of the residual breast volume (RBV) is not clear. Therefore, we developed an MRI tool that allows to easily assess the RBV. In this study we evaluated factors associated with RBV after skin or nipple sparing mastectomy (SSM/NSM) in breast cancer BRCA pathogenic variant (PV) carriers who underwent both therapeutic and risk reducing SSM/NSM and its relation to breast cancer outcomes using an innovative MRI-based tool.

METHODS

Data of breast cancer BRCA PV who were treated between 2006 and 2020 were retrieved from of the oncogenetics unit databases. Only patients who underwent SSM/NSM and had a postoperative breast MRI available for analysis were included. Data collected included demographics, clinicopathological features, and outcomes. The MRI tool was developed by a breast cancer imaging laboratory. A logistic regression test and 95% confidence interval (CI) were used to assess the associated risk of increased RBV. A forward stepwise linear regression was used to correlate tumour-patient specific factors and RBV, and a Kaplan-Meier curve to show the probability of locoregional relapse.

RESULTS

A total of 84 patients undergoing 89 mastectomies were included. At a median follow-up of 98 months, 5 local, 2 regional, and 4 distant recurrences were observed. RBV was not significantly related with breast cancer outcomes (p value = NS). A higher body mass index (BMI) was associated with a higher RBV (p < 0.0001). A larger number of involved axillary nodes was associated with a smaller RBV (p = 0.025). The RBV on the risk-reducing mastectomy side was significantly higher compared to the breast cancer side (p value = 0.007). Local recurrences occurred in the vicinity of the primary tumour.

[News in breast oncology genetics for female and male population]

OBJECTIVES

Breast oncology genetics emerged almost 30 years ago with the discovery of the BRCA1 and BRCA2 genes. The evolution of analytical practices has progressively allowed access to tests whose results now have a considerable impact on the management of both female and male breast cancers. The Sénologie commission of the Collège national des gynécologues et obstétriciens français (CNGOF) asked five specialists in breast surgery, oncology and oncological genetics to draw up a summary of the oncogenetic testing criteria used and the clinical implications for the female and male population of the test results, with or without an identified causal variant. In the case of proven genetic risk, surveillance, risk-reduction strategies, and the specificities of surgical and medical management (with PARP inhibitors in particular) were updated.

METHODS

This summary was based on national and international guidelines on the monitoring and therapeutic management of genetic risk, and a recent review of the literature covering the last five years.

RESULTS

Despite successive technical developments, the probability of identifying a causal variant in a situation suggestive of a predisposition to breast and ovarian cancer remains around 10% in France. The risk of breast cancer in women with a causal variant of the BRCA1, BRCA2, PALB2, TP53, CDH1 and PTEN genes is estimated at between 35% and 85% at age 70. The presence of a causal variant in one of these genes is the subject of different recommendations for men and women, concerning both surveillance, the age of onset and imaging modalities of which vary according to the genes involved, and risk-reduction surgery, which is possible for women as soon as their risk level exceeds 30% and remains exceptionally indicated for men. In the case of breast cancer, PARP inhibitors are a promising new class of treatment for BRCA germline mutations.

CONCLUSION

A discipline resolutely focused on understanding molecular mechanisms, screening and preventive medicine/surgery, oncology genetics is currently also involved in new medical/surgical approaches, the long-term benefits/risks of which will need to be monitored.

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.