Results of a prospective phase II national study: Prophylactic radical fimbriectomy (NCT01608074), in women with a documented high risk of breast/ovarian cancer—Final pathological results and outcomes

1594 Background: Risk-reducing salpingo-oophorectomy (RRSO) is the gold standard in surgical prophylaxis of pelvic high-grade serous carcinoma (HGSC) for women at risk of breast/ovarian cancer. Due to significant adverse effects of early oophorectomy, 20-30% of women delay or deny performing this operation. Recent data highlight the fallopian origin of most pelvic HGSC, especially its fimbrial part. Thus, we suggested a new two-step risk-reducing procedure: the radical fimbriectomy (RF) with delayed oophorectomy (DO) (Leblanc et al Gyn Oncol 2011), leading to the current RF/DO Phase 2 study. We present the definitive results on primary and secondary objectives of this trial. Methods: BRCA1/2 carriers or any women with a documented familial risk of breast/ovarian cancer were first counseled to perform a classical laparoscopic RRSO. If they denied, they were offered to enter the RF/DO study. All specimens were submitted to the SEE-FIM pathological protocol. Pathological data along with all intra- and 30-day and beyond post-operative adverse events were prospectively recorded. Follow-up consisted in an annual clinical breast and gynecological examination, with tumor markers and hormonal status assessment. Primary endpoint was the rate of pelvic serous carcinoma. Secondary endpoints were procedure morbidity, rates of tubal abnormalities, breast cancer, secondary oophorectomy. Results: From January 2012 to October 2014, 121 RF were performed: 120 by laparoscopy, 1 laparotomy (concurrent myomectomy). An occult neoplasia was found in 3 cases with 1 invasive HGSC. Intraoperative complications were two grade1 bleedings without transfusion with no grade ≥3 early post-operative or delayed complication. With a median follow-up of 5.3 years (0.2 -7.6), no patient developed any pelvic HGSC, 21 patients developed a breast cancer (3 de novo, 18 recurrences/contralateral.). 1 cancer-free BRCA1-mutated lady delivered safe twins, after an uneventful post-RF pregnancy obtained with assisted reproductive technology (ART). Overall, 29 women underwent DO (by choice: 12 or menopause: 17) resulting in grade 3b complication in 1 case, but no pathological abnormality. Conclusions: RF/DO appears as a safe, well tolerated and effective procedure in terms of occult neoplasia detection. A successful pregnancy with ART was possible after radical fimbriectomy. Longer follow-up and larger cohort are necessary to confirm its efficacy in terms of ovarian cancer prophylaxis. Clinical trial information: NCT01608074.