P25: Beyond BRCA: Oncologic Safety of Nipple-Sparing Mastectomy for Other Risk Gene Mutation Carriers
A. Henriquez, M.E. Garstka*, B.R. Kelly, A. Webster, J. Khubchandani, S. Coopey, M. Gadd, K. Hughes, A. Nguyen, T. Oseni, M. Specht, B.L. Smith, Massachusetts General Hospital, Boston, Massachusetts, UNITED STATES|
Fellow Massachusetts General Hospital Boston , Massachusetts, United States
Background: Nipple-sparing mastectomy (NSM) is increasingly offered for treatment and prevention of breast cancer. Widespread use of multigene panel testing for breast cancer patients and their relatives now identifies a wide variety of risk gene mutations. Current data supports NSM for patients with BRCA1 and BRCA2 mutations, but little is known about NSM for other risk gene mutations.
Methods: Patients with risk gene mutations other than BRCA1 and BRCA2 undergoing NSM from 2/2009-12/2019 were identified in a prospective database of consecutive NSM. Patient, tumor, treatment and outcomes data were collected. Group 1 patients had mutations included in most breast cancer risk gene panels (ATM, BARD1, CDH1, CHEK2, P53, PALB2, PTEN) and Group 2 had mutations with low/no definite impact on breast cancer risk (APC, BRIP, MET, MSH2, MSH6, MTRHF, MUTYH, NBN, NF1, PIK3CA, RAD50, RAD51). Patients with only variants of unknown significance (VUS) were excluded.
Results: Overall, 87 mutation carriers had 160 NSM. In Group 1, 62 patients had 45 NSM for known cancer and 66 planned prophylactic NSM, 4 of which contained unexpected cancer. Mean age was 45 years (22-65). These 49 cancers included 16 (33%) stage 0, 13 (26%) stage I, 17 (35%) stage II and 3 (6%) stage III tumors. At 31 months median follow-up, Group 1 recurrences included 2 (4%) distant and locoregional, 2 (4%) distant only, 2 (4%) locoregional only, but no nipple-areola complex (NAC) recurrences. Overall survival was 95%. In Group 2, 25 patients underwent 24 NSM for known cancer and 21 prophylactic NSM, with no unexpected cancers found in prophylactic NSM. Mean age was 52.4 years (27-73). There were 7 (29%) stage 0, 12 (50%) stage I, 4 (17%) stage II and 1 (4%) stage III tumors. At 26.5 months median follow-up, Group 2 recurrences included 3 (12.5%) distant only, 3 (12.5%) locoregional only, but no NAC recurrences. Overall survival was 96%.
Conclusions: Early rates of distant, nipple and other locoregional recurrence are low after NSM in carriers of risk genes other than BRCA1 and BRCA2. Incidental cancers were seen only in carriers of genes known to be associated with breast cancer risk.