Sentinel lymph node biopsy in low risk settings

Incidence of Cancer and Role of Sentinel Lymph Node Biopsy in BRCA Mutation Carriers Undergoing Prophylactic Mastectomies

INTRODUCTION

Breast surveillance in patients with BRCA mutations include mammography (MMG) and MRI. Patients may elect to undergo risk-reducing bilateral prophylactic mastectomies (BPM). Sentinel lymph node biopsies (SLNB) are frequently performed and associated with increased morbidity. This study sought to determine the correlation between preoperative imaging and the final pathology and evaluate the role of SLNB in these high-risk patients.

METHODS

A prospective database identified BRCA patients who underwent BPM between 2006 and 2022. Imaging, pathology, and operative reports were reviewed.

RESULTS

170 patients with BRCA 1/2 mutations were identified. 162 (95.3%) had imaging within one year of BPM. Of these, 28 (17.3%) patients had a MMG/ultrasound, 53 (32.7%) had an MRI, and 81 (50%) had both; 21/162 (13.0%) patients had abnormal imaging. Bilateral SLNB were performed in 31 (18.2%) patients, of which 7 had abnormal imaging; unilateral SLNB were performed in 4 (2.4%) patients, of which 3 had abnormal imaging. 11/170 (6.4%) patients had a malignancy and only one (9%) of these patients had imaging abnormalities. 1/170 (0.6%) patient had an invasive carcinoma requiring an axillary lymph node dissection (ALND), and 10/170 (5.9%) patients had ductal carcinoma in situ (DCIS). 25/170 (14.7%) had ADH/ALH. Only 7/170 (4.1%) patients had imaging abnormalities and abnormal pathology. All SLNB and ALND performed demonstrated no metastatic disease.

DISCUSSION

There is a high rate of discordance between preoperative imaging prior to surgery in BRCA patients undergoing prophylactic mastectomies and final pathology. This study does not support routine SLNB at the time of BPM.

Prophylactic mastectomy and occult malignancy: Surgical and imaging considerations

BACKGROUND

Sentinel node biopsy (SLNB) is not routinely recommended for patients undergoing prophylactic mastectomy (PM), yet omission remains a subject of debate among surgeons. A modern patient cohort was examined to determine occult malignancy (OM) incidence within PM specimens to reinforce current recommendations.

METHODS

All PM performed over a 5-year period were retrospectively identified, including women with unilateral breast cancer who underwent synchronous or delayed contralateral PM or women with elevated cancer risk who underwent bilateral PM.

RESULTS

The study population included 772 patients (598 CPM, 174 BPM) with a total of 39 OM identified: 17 invasive cancers (14 CPM, 3 BPM) and 22 DCIS (19 CPM, 3 BPM). Of the 86 patients for whom SLNB was selectively performed, 1 micrometastasis was identified. In the CPM cohort, risk of OM increased with age, presence of LCIS of either breast, or presence of a non-BRCA high-penetrance gene mutation, while preoperative magnetic resonance imaging was associated with lower likelihood of OM.

CONCLUSIONS

Given the low incidence of invasive OM in this updated series, routine SLNB is of low value for patients undergoing PM. For patients with indeterminate radiographic findings, discordant preoperative biopsies, LCIS, or non-BRCA high-penetrance gene mutations, selective SLNB implementation could be considered.