Audit of bilateral mastectomy (BMS) in the very high risk (VHR) National Breast Screening Programme (NHSBSP)-inequality of access to bilateral risk reducing mastectomy (RRM)?

Abstract

The VHR NHSBSP screens women with VHR genes and supradiaphragmatic radiotherapy aged 10-35 (XRTC). Women undergoing bilateral mastectomies (BMS) are ceased from screening. This is the first known audit of women ceasing VHR screening to characterise demographics and outcomes. Screening & ceasing data for VHR women from 2 screening services from 2021-2024 were reviewed for risk category, ceasing age, whether there was a therapeutic (TM) or RRM. The pathology of BMS were reviewed for any undiagnosed cancers. 2564 were invited and 1963 VHR women screened. 97 women were ceased. 57/97 (58.8%) underwent bilateral RRM and 4 underwent single RRM (previous contralateral mastectomy for breast cancer). 35/97 (36.1%) had TM & contralateral RRM and 1 had bilateral TM. The median age for bilateral RRM is 42 (range 25-67) and for RRM with TM is 42 (range 30-69). All women undergoing bilateral RRM or unilateral RRM (with previous contralateral TM) were gene carriers; 59/61 were BRCA carriers. All 5 XRTC women who had RRM also had TM for breast cancer. Unsuspected DCIS were found in 3 women. Our audit shows that RRM women were all gene carriers. No XRTC women underwent bilateral RRM even though 17% VHR screening women had XRTC (with similar cancer detection rate to BRCA carriers; 19.9 vs 21.5/1000 screened). This suggests potential inequality of counselling and access to RRM for XRTC women compared to VHR gene carriers. We recommend that the audit is extended nationally to assess and to evaluate current practice on risk counselling for XRTC women.