Occult Breast Cancer in High-Risk Gene-Positive Pakistani Women Undergoing Contralateral Prophylactic Mastectomy/Prophylactic Mastectomy: Implications for Sentinel Lymph Node Biopsy.

Introduction: Sentinel lymph node biopsy (SLNB) of the axilla is standard in breast cancer (BC) management; however, its role in prophylactic/contralateral prophylactic mastectomy (CPM) is still questioned. To avoid future consequences on surgical morbidity and socioeconomic aspects in low and middle-income countries (LMICs), we intend to determine the prevalence of occult breast cancer (OBC) among CPM cases.

Objective: To determine the prevalence of OBC in patients undergoing prophylactic mastectomy (PM).

Design: This is a retrospective cohort study.

Materials And Methods: This retrospective cohort study is conducted at a tertiary-care hospital from January 2017 to December 2022. All individuals with the positive genetic test for high-risk breast cancer (HRBC) genes who underwent PMs/CPM at our centre were included. We analysed data using SPSS version 23.0.

Results: Twenty-six mutation-positive females underwent PM/CPM (16.1%). Two (7.69%) of 26 had later post-PM recurrence. Only 8 (30.76%) patients had SLNB and all were negative. No OBC was seen in PM/CPM specimens, whereas 3 (11.5%) had atypical ductal hyperplasia (ADH). Two of the ADH had BI-RADS-1, whereas 1 was BI-RADS-4 (33.3%) on the preoperative assessment. Results also showed that with an increase in the tumour grade of the diseased breast, the BI-RADS score of the asymptomatic breast was subsequently increased ( = .029).

Conclusion: Our study shows negative OBCs in PM/CPM cases with persistently negative SLNB results; however, ADH is identified in 11.5% of specimens. Our results suggest that SLNB can be safely omitted in patients undergoing CPM, but, preoperatively, patient and disease factors should be considered.