MRI-based quantification of residual fibroglandular tissue of the breast after conservative mastectomies

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.

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.

Updated findings of skin flap thickness and residual breast tissue after mastectomy for breast cancer: a systematic review of the literature

BACKGROUND

There is limited evidence on the ideal retention thickness of skin flap in mastectomy. Residual breast tissue (RBT) after mastectomy still represents an unknown risk for local recurrence or new breast cancer lesions. We made this systematic review to identify the optimal flap after mastectomy with minimal complications and better oncological safety.

METHODS

A systematic review was performed using MEDLINE search in PubMed, Embase, and Cochrane Library with the search terms relevant to skin flap thickness and residual breast tissue in breast cancer patients undergoing mastectomy.

RESULTS

Twenty-one studies were included of which fifteen studies enrolled 3814 patients who received mastectomy, and additional six studies were based on cadavers or breast specimens. Four studies confirmed the presence of the superficial fascial layer (Camper's fascia) which can theoretically be used as an anatomical marker for flap retention during mastectomy. Two other studies confirmed Camper's fascia deficiency to a greater or lesser extent. The flap thickness ranged from 3.8 mm to 23 mm in 2692 patients of 7 studies, which was related to BMI, breast size, and examination modalities. Two retrospective and one prospective studies confirmed flaps exceeding 5 mm could significantly increase postoperative complications. Nine studies including 1122 patients explored the association among flap thickness, RBT, and complications, 3 studies of which confirmed excessive flap thickness could cause a significant increase in RBT, which proved to be a potential risk factor for local recurrence in 3 studies. Flaps beyond 5 mm were also found to significantly increase the chance of local recurrence in 4 studies.

CONCLUSION

Camper's fascia can serve as an ideal demarcation between fat and breast tissue based on most current studies. 5 mm thickness of the flap retention in mastectomy is recommended if Camper's fascia is absent or obscure, through which better cosmetic outcomes and less RBT can be achieved.

Pathology and resection margins following mastectomy prior to immediate breast reconstruction

Risk of local recurrence (LR) (and even distant disease-free survival) after mastectomy is associated with margin status. Furthermore, the vast majority of LR are located at the anterior (superficial) margin. Margins in mastectomy are considered anatomical borders and not true resection margins; such a conception may erroneously lead to underestimation of the risk of LR after mastectomy. If dissection is accurate along the fascia, only skin, subcutaneous tissue and minimal residual breast gland tissue (rBGT) are expected to remain in the patient. However, the subcutaneous fascia is an inconsistent anatomical structure that may be absent in almost half of patients. Studies and routine clinical practice suggest that resection may frequently, though often focally, be within the breast glandular tissue leaving various amounts of rBGT. Such areas may be nidus for subsequent de novo or recurrent premalignant or malignant disease. There is no consensus on handling of close/positive margins and intervention is extrapolated from studies on breast conserving surgery with subsequent radiotherapy. Handling of a close/positive margin is complicated by poor correlation between the ex vivo findings on the specimen and the attempt to relocate the area of concern in a patient with reconstructed breasts. In this clinical practice review, we strongly advocate for reporting of the lesion-to-margin distance in mastectomies to collect further evidence on the association between LR and margin status.

Use of Magnetic Resonance Imaging for Evaluating Residual Breast Tissue After Robotic-Assisted Nipple-Sparing Mastectomy in Women With Early Breast Cancer

OBJECTIVE

Prospective studies on postoperative residual breast tissue (RBT) after robotic-assisted nipple-sparing mastectomy (R-NSM) for breast cancer are limited. RBT presents an unknown risk of local recurrence or the development of new cancer after curative or risk-reducing mastectomies. This study investigated the technical feasibility of using magnetic resonance imaging (MRI) to evaluate RBT after R-NSM in women with breast cancer.

MATERIALS AND METHODS

In this prospective pilot study, 105 patients, who underwent R-NSM for breast cancer at Changhua Christian Hospital between March 2017 and May 2022, were subjected to postoperative breast MRI to evaluate the presence and location of RBT. The postoperative MRI scans of 43 patients (age, 47.8 ± 8.5 years), with existing preoperative MRI scans, were evaluated for the presence and location of RBT. In total, 54 R-NSM procedures were performed. In parallel, we reviewed the literature on RBT after nipple-sparing mastectomy, considering its prevalence.

RESULTS

RBT was detected in 7 (13.0%) of the 54 mastectomies (6 of the 48 therapeutic mastectomies and 1 of the 6 prophylactic mastectomies). The most common location for RBT was behind the nipple-areolar complex (5 of 7 [71.4%]). Another RBT was found in the upper inner quadrant (2 of 7 [28.6%]). Among the six patients who underwent RBT after therapeutic mastectomies, one patient developed a local recurrence of the skin flap. The other five patients with RBT after therapeutic mastectomies remained disease-free.

CONCLUSION

R-NSM, a surgical innovation, does not seem to increase the prevalence of RBT, and breast MRI showed feasibility as a noninvasive imaging tool for evaluating the presence and location of RBT.

Residual fibroglandular breast tissue after mastectomy is associated with an increased risk of a local recurrence or a new primary breast cancer"

BACKGROUND

Residual fibroglandular breast tissue (RFGT) following a mastectomy has been claimed to be associated with the occurrence of an in-breast local recurrence (IBLR) or new primary tumor (NP). Yet, scientific evidence proving this assumption is lacking. The primary aim of the study was to verify whether RFGT following a mastectomy is a risk factor for an IBLR or NP.

METHODS

This retrospective analysis included all patients that underwent a mastectomy and were followed up at the Department of Obstetrics and Gynecology of the Medical University of Vienna between 01.01.2015 and 26.02.2020. RFGT volume (assessed on magnetic resonance imaging) was correlated with the prevalence of an IBLR and a NP.

RESULTS

A total of 105 patients (126 breasts) following a therapeutic mastectomy were included. After a mean follow-up of 46.0 months an IBLR had occurred in 17 breasts and a NP in 1 breast. A significant difference in RFGT volume was observed between the disease-free cohort and the subgroup with an IBLR or NP (p = .017). A RFGT volume of ≥ 1153 mm³ increased the risk by the factor 3.57 [95%CI 1.27; 10.03].

CONCLUSIONS

RFGT volume is associated with an increased risk for an IBLR or NP.

Optimising post-operative radiation therapy after oncoplastic and reconstructive procedures

Surgical techniques for breast cancer have been refined over the past decades to deliver an aesthetic outcome as close as possible to the contralateral intact breast. Current surgery further allows excellent aesthetic outcome even in case of mastectomy, by performing skin sparing or nipple sparing mastectomy in combination with breast reconstruction. In this review we discuss how to optimise post-operative radiation therapy after oncoplastic and breast reconstructive procedures, including dose, fractionation, volumes, surgical margins, and boost application.

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.

Inter- and intra-observer agreement on evaluating the presence of residual glandular tissue with magnetic resonance tomography following prophylactic mastectomy

BACKGROUND

There are no published international consensus or guideline documents regarding appropriate medical follow-up for women with hereditary increased risk of breast cancer who opt for prophylactic mastectomy. Moreover, it is not known whether breast magnetic resonance imaging (MRI) performed after a prophylactic mastectomy is a reproducible method for evaluating whether clinically relevant amounts of residual glandular tissue remains.

PURPOSE

To evaluate the inter- and intra-observer agreement on detecting residual glandular tissue with MRI.

MATERIAL AND METHODS

In total, 40 women previously operated with prophylactic mastectomy underwent MRI and two breast radiologists (R1 and R2) independently assessed the presence of residual glandular tissue. Inter- and intra-rater agreements were assessed using Cohen's kappa (k).

RESULTS

Residual glandular tissue was found in 69 of 248 quadrants (27.8%) and 32 of 62 breasts (51.6%) by R1 and 77 of 248 quadrants (31.1%) and 35 of 62 breasts (56.5%) by R2. The interrater agreement was observed to be moderate (k = 0.554) and the intra-rater agreement was observed to be substantial (k = 0.623).

CONCLUSION

In conclusion, the inter-and intra-rater observer agreement in regard to detection of residual glandular tissue was not excellent, which would be desirable for a method considered reproducible enough to be used as a surveillance tool after the surgical procedure in order to ensure that there is no relevant residual glandular tissue remaining warranting further follow-up. More research is needed, as well as establishment of precise protocols, before using the method in risk assessment of remaining glandular tissue and breast cancer risk.

The patterns and spatial locations of local recurrence in breast cancer with implant-based reconstruction after mastectomy

BACKGROUND AND PURPOSE

The European Society for Radiotherapy and Oncology (ESTRO) recently defined delineation guidelines for the clinical target volume for postmastectomy radiation therapy (PMRT) after immediate implant-based reconstruction for early-stage breast cancer. We analyzed the three-dimensional location and pattern of local recurrence in accordance with the reconstruction type and ESTRO-target volume.

MATERIALS AND METHODS

This retrospective study involved patients who had undergone mastectomy with implant reconstruction between 2010 and 2019 and who had local recurrence as the first event. For mapping analysis, one subpectoral and one prepectoral implant patient were selected. All recurrence lesions were contoured and mapped in a representative case.

RESULTS

A total of 1,327 patients with breast cancer who underwent mastectomy and implant-based breast reconstruction were identified; 51 were enrolled with a total of 65 lesions. In subpectoral implant patients, 93% of recurrences were located in the ESTRO-target volume. No recurrence occurred in the implant pocket, but 7% of the recurrent tumors developed in the pectoralis major and deep thoracic muscle. In prepectoral implant patients, all recurrent tumors occurred within the ESTRO-target volume.

CONCLUSION

The ESTRO-target volume in PMRT after reconstruction encompassed most local recurrences in patients who underwent mastectomy with immediate implant reconstruction. Our results support the application of the ESTRO Advisory Committee for Radiation Oncology Practice consensus guideline for target volume of PMRT after immediate implant-based reconstruction for early-stage breast cancer.

Pregnancy induced hyperplasia of residual breast tissue following risk reducing contralateral mastectomy - simply interesting or a clinically important observation

After a diagnosis of breast cancer women with increased genetic risk often have a risk reducing contralateral mastectomy, and may opt for a nipple or skin sparing mastectomy with immediate reconstruction. A variable amount of residual breast tissue remains which may substantially increase in volume during pregnancy. Whether this increases later risk of breast cancer is unknown. We describe the clinical details of 3 patients with a history of unilateral breast cancer, including 2 with a BRCA mutation, who developed hyperplasia of residual breast tissue in the 3rd trimester of a later pregnancy. They all had a delayed contralateral risk reducing skin sparing mastectomy and immediate reconstruction. Pregnancy occurred some years later. We summarise their management, review the literature and raise questions for discussion. All developed prominent hyperplasia of breast tissue in the 3rd trimester that was clinically obvious asymmetrical breast swelling in the reconstructed contralateral breast. MRI demonstrated substantial breast tissue. The risk of breast cancer, particularly in those at high genetic risk developing in the residual breast tissue is unknown but in view of the volume, breast tissue was excised postpartum. This phenomenon of pregnancy induced hyperplasia of breast tissue after risk reducing mastectomy is not well described .There is residual breast tissue following a risk reducing subcutaneous mastectomy. The risk factors include age and skin flap thickness. MRI can demonstrate the residual breast tissue. Pregnancy induced hyperplasia of residual breast tissue may occur after risk reducing mastectomy with a hypothetical increased risk of subsequent breast cancer.

A Cost Decision Model Supporting Treatment Strategy Selection in BRCA1/2 Mutation Carriers in Breast Cancer

In this paper, a cost decision-making model that compares the healthcare costs for diverse treatment strategies is built for BRCA-mutated women with breast cancer. Moreover, this model calculates the cancer treatment costs that could potentially be prevented, if the treatment strategy with the lowest total cost, along the entire lifetime of the patient, is chosen for high-risk women with breast cancer. The benchmark of the healthcare costs for diverse treatment strategies is selected in the presence of uncertainty, i.e., considering, throughout the lifetime of the patient, the risks and complications that may arise in each strategy and, therefore, the costs associated with the management of such events. Our results reveal a clear economic advantage of adopting the cost decision-making model for benchmarking the healthcare costs for various treatment strategies for BRCA-mutated women with breast cancer. The cost savings were higher when all breast cancer patients underwent counseling and genetic testing before deciding on any diagnostic-therapeutic path, with a probability of obtaining savings of over 75%.

Superficial margins in skin sparing and nipple sparing mastectomies for DCIS: A margin of potential concern

Skin-sparing and nipple-sparing mastectomies with immediate reconstruction for breast cancer are increasing. The superficial fascia is considered a natural border and the superficial margin may not be evaluated. We emphasize the need for reporting of the superficial margin status in these procedures to obtain valid information on its association with local recurrence risks.

Post-mastectomy surveillance of BRCA1/BRCA2 mutation carriers: Outcomes from a specialized clinic for high-risk breast cancer patients

Female BRCA1/BRCA2 mutation carriers may elect bilateral risk-reducing mastectomy. There is a paucity of data on yield of imaging surveillance after risk-reducing mastectomy. This retrospective study focused on female BRCA1/BRCA2 mutation carriers who underwent bilateral mastectomy either as primary preventative, or as secondary preventative, after breast cancer diagnosis. All participants underwent breast imaging at 6- to 12-month intervals after mastectomy. Data on subsequent breast cancer diagnosis and timing were collected and compared between the groups. Overall, 184 female mutation carriers (134 BRCA1, 45 BRCA2, 5 both BRCA genes) underwent bilateral mastectomy after initial breast cancer diagnosis, between April 1, 2009 and August 31, 2018. During a mean follow-up of 6.2 ± 4.2 years, 13 (7.06%) were diagnosed with breast cancer; 12 ipsilateral (range: 0.4-28.8 years) and 1 contralateral breast cancer, 15.9 years after surgery. On the contrary, among asymptomatic BRCA1 (n = 40) and BRCA2 (n = 13) mutation carriers who underwent primary risk-reducing mastectomy (mean age at surgery 39.5 ± 8.4 years); none has developed breast cancer after a mean follow-up of 5.4 ± 3.4 years. BRCA1/BRCA2 mutation carriers with prior disease who underwent risk-reducing mastectomy after breast cancer diagnosis are still prone for developing ipsi or contralateral breast cancer, and therefore may benefit from continues clinical and imaging surveillance, unlike BRCA1/BRCA2 mutation carriers who undergo primary preventative bilateral mastectomy.

A multidisciplinary view of mastectomy and breast reconstruction: Understanding the challenges

The current review paper was written in collaboration with breast cancer surgeons from the European Breast Cancer Research Association of Surgical Trialists (EUBREAST), a breast pathologist from the Danish Breast Cancer Group (DBCG), and representatives from the European SocieTy for Radiotherapy & Oncology (ESTRO) breast cancer course. Herein we summarize the different mastectomies and reconstruction procedures and define high-risk anatomical areas for breast cancer recurrences, to further specify the challenges in the surgical procedure, histopathological evaluation, and target volumes in case of postmastectomy irradiation, as recommended by the ESTRO guidelines according to the surgical procedure. The paper has original figures and illustrations for all disciplines for in-depth understanding of the differences between the procedures.

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Mastectomy techniques and reconstruction evolved to improve cosmetic outcomes.

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Different techniques maybe associated with different amount of residual breast tissue.

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More data is needed to estimate who are the patients at risk for residual disease or recurrence.

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Multidisciplinary work needed to individualise treatment for optimal oncological outcomes while maintaining the significant improvements in achieving better cosmesis for these patients.

Screening in patients with increased risk of breast cancer (part 2). Where are we now? Actual MRI screening controversies

For women with a high risk of breast cancer, early detection plays an important role. Due to the high incidence of breast cancer, and at a younger age than in the general population, screening begins earlier, and there is considerable evidence that magnetic resonance is the most sensitive diagnostic tool, and the principal American and European guidelines agree on the recommendation to perform annual magnetic resonance (with supplemental annual mammography) as an optimal mode of screening. In addition to the absence of current consensus on which patients should be included in the recommendation for magnetic resonance screening (widely discussed in the introduction of part 1 of this work), there are other aspects that are different between guidelines, that are not specified, or that are susceptible to change based on the evidence of several years of experience, that we have called «controversies», such as the age to begin screening, the possible advisability of using a different strategy in different subgroups, performing alternate versus synchronous magnetic resonance and mammography, the age at which to terminate the two techniques, or how to follow up after risk reduction surgery.The aim of the second part of the paper is, by reviewing the literature, to provide an update in relation to some of the main «controversies» in high risk screening with magnetic resonance. And finally, based on all this, to propose a possible model of optimal and updated screening protocol.

Residual Glandular Breast Tissue After Mastectomy: A Systematic Review

BACKGROUND

The goal of mastectomy is remove all of the glandular breast tissue (BGT) without compromising skin flaps viability. The purpose of this systematic review was to localize and/or estimate the amount of residual BGT (rBGT) after mastectomy and to identify factors that could be related to rBGT and/or residual disease.

METHODS

We conducted a PubMed search. The report was subdivided according to the method used to evaluate the presence of rBGT. A total of 16 publications were included in our final report. Two main methods for identifying rBGT included imaging (i.e., MRI scan) and histological evaluation at the time of mastectomy.

RESULTS

The rate of rBGT was reported in up to 100% of the patients and was found to be associated mainly with the type of surgical resection, indication, and surgeon's expertise. Residual breast tissue can be found in all areas of the remaining chest wall, mostly in the skin-flaps, and more frequently underneath the nipple-areola complex.

Winter is over: The use of Artificial Intelligence to individualise radiation therapy for breast cancer

Artificial intelligence demonstrated its value for automated contouring of organs at risk and target volumes as well as for auto-planning of radiation dose distributions in terms of saving time, increasing consistency, and improving dose-volumes parameters. Future developments include incorporating dose/outcome data to optimise dose distributions with optimal coverage of the high-risk areas, while at the same time limiting doses to low-risk areas. An infinite gradient of volumes and doses to deliver spatially-adjusted radiation can be generated, allowing to avoid unnecessary radiation to organs at risk. Therefore, data about patient-, tumour-, and treatment-related factors have to be combined with dose distributions and outcome-containing databases.

ESTRO ACROP consensus guideline for target volume delineation in the setting of postmastectomy radiation therapy after implant-based immediate reconstruction for early stage breast cancer

Immediate breast reconstruction (IBR) rates after mastectomy are increasing. Postmastectomy radiation therapy (PMRT) contouring guidelines for target volumes in the setting of IBR are lacking. Therefore, many patients who have had IBR receive PMRT to target volumes similar to conventional simulator-based whole breast irradiation. The aim of this paper is to describe delineation guidelines for PMRT after implant-based IBR based on a thorough understanding of the surgical procedures, disease stage, patterns of recurrence and radiation techniques. They are based on a consensus endorsed by a global multidisciplinary group of breast cancer experts.

Residual glandular tissue (RGT) in BRCA1/2 germline mutation carriers with unilateral and bilateral prophylactic mastectomies

BACKGROUND

Prophylactic mastectomy (PME) is increasingly performed in women carrying deleterious BRCA1 and BRCA2 germline mutations. The oncologic risk resulting from residual fibroglandular tissue (RGT) is unknown.

METHODS

All women who had received a mastectomy and at least one postoperative breast MRI, between 2006 and 2016 were extracted from the register of the Center for Hereditary Breast and Ovarian Cancer Cologne (CHBOC). The index MRI was evaluated in terms of basic clinical data and the morphological criteria of RGT. The RGT volume was measured in diameter and was semi-automatically evaluated using software.

RESULTS

We identified 169 women carrying BRCA1/2 mutations who underwent prophylactic and curative mastectomy: a total of 338 breasts. RGT was found in 128 of the 338 breasts (37.9%). 68 of the 128 breasts (53.1%) were related to bilateral PME, 37 (28.9%) to unilateral PME and 23 (18.0%) to curative mastectomy. RGT was predominantly unifocal and located in the retroareolar breast region. RGT was observed more often after bilateral PME (p < 0.0001). In this subgroup, the nipple-sparing mastectomy dominated (108 of 136, 79.4%), in contrast to 23 standard mastectomies (23 of 94, 24.5%) in the subgroup of curative mastectomy (23%). There was a trend towards higher amounts of RGT in surgical units with fewer mastectomies performed. During follow-up, two breast cancers were detected after bilateral and unilateral PME, respectively.

CONCLUSIONS

Our results suggest that the indication for surgery and in particular the selected surgical procedure affect the surgical outcome with respect to RGT. Oncological safety should not be neglected, especially in the high-risk group of BRCA1/2 mutation carriers.

Prospective Evaluation of Residual Breast Tissue After Skin- or Nipple-Sparing Mastectomy: Results of the SKINI-Trial

OBJECTIVE

This study was designed to investigate the presence of residual breast tissue (RBT) after skin-sparing mastectomy (SSM) and nipple-sparing mastectomy (NSM) and to analyse patient- and therapy-related factors associated with RBT. Skin-sparing mastectomy and NSM are increasingly used surgical procedures. Prospective data on the completeness of breast tissue resection is lacking. However, such data are crucial for assessing oncologic safety of risk-reducing and curative mastectomies.

METHODS

Between April 2016 and August 2017, 99 SSM and 61 NSM were performed according to the SKINI-trial protocol, under either curative (n = 109) or risk-reducing (n = 51) indication. After breast removal, biopsies from the skin envelope (10 biopsies per SSM, 14 biopsies per NSM) were taken in predefined radial localizations and assessed histologically for the presence of RBT and of residual disease.

RESULTS

Residual breast tissue was detected in 82 (51.3%) mastectomies. The median RBT percentage per breast was 7.1%. Of all factors considered, only type of surgery (40.4% for SSM vs. 68.9% for NSM; P < 0.001) and surgeon (P < 0.001) were significantly associated with RBT. None of the remaining factors, e.g., skin flap necrosis, was associated significantly with RBT. Residual disease was detected in three biopsies.

CONCLUSIONS

Residual breast tissue is commonly observed after SSM and NSM. In contrast, invasive or in situ carcinomas are rarely found in the skin envelope. Radicality of mastectomy in this trial is not associated with increased incidence of skin flap necrosis. ClinicalTrials.gov Identifier NCT03470909.