Retrospective study of a 16 year cohort of BRCA1 and BRCA2 carriers presenting for RRSO: Prevalence of invasive and in-situ carcinoma, with follow-up.

OBJECTIVES

Carriers of BRCA1 and BRCA2 mutations are at increased risk of high grade serous carcinoma and are therefore offered risk-reducing salpingo-oophorectomy (RRSO) by 40-45 years. Most of these carcinomas are believed to arise in the fallopian tube from serous tubal intraepithelial carcinoma (STIC). We conducted a retrospective study on the prevalence of high grade serous carcinoma and STIC in BRCA1/2 carriers presenting for RRSO, and their follow-up.

METHODS

Consecutive BRCA1/2 carriers presenting for an RRSO at Erasmus MC (2000-2016) were studied. SEE-FIM pathology protocol was followed from 2010 onwards. For the cases with carcinoma and/or STIC, the histology was reviewed and immunohistochemistry (p53 & MIB-1) was performed. Next Generation Targeted Sequencing (NGTS) for TP53 mutation was used to establish clonality in 2 cases.

RESULTS

Of the 527 included patients, 68% were BRCA1, 31.6% were BRCA2, and 0.4% carried both mutations. The prevalence of high grade serous carcinoma was 2.3% (12/527); 59% of these were of tubal origin. High grade serous carcinoma was more common in patients operated on after the recommended age (p = 0.03). Isolated STIC was present in 0.8% (4/527). Two BRCA1 carriers with isolated STIC at RRSO developed peritoneal serous carcinoma >7 years later. Identical TP53 mutations in the peritoneal serous carcinoma and the preceding STIC established their clonal origin.

CONCLUSIONS

High grade serous carcinoma is more common in BRCA1/2 carriers presenting for RRSO after the recommended age, and is more often of tubal origin. Longer follow up of patients with STIC at RRSO should be considered.