Prevention of primary and contralateral breast cancer by risk reducing salpingo-oophorectomy in high risk women with a BRCA1/2 mutation or familial predisposition.

Abstract

Abstract Abstract #504 Introduction: Risk reducing salpingo-oophorectomy (RRSO) has become an important preventive option against ovarian/fallopian tube cancer, while it is also risk reducing regarding breast cancer (BC) in women with a BRCA1 or BRCA2 mutation. Recently a difference in efficacy of RRSO concerning the occurrence of BC has been suggested for BRCA1 and BRCA2 mutation carriers, while no data are available on the protective effect of RRSO in women from a hereditary breast/ovarian cancer (HBOC) family without a proven BRCA mutation. Further, it is not known whether the BC risk reduction after RRSO equally applies to primary (PBC) and contralateral BC (CBC).
 Methods: The occurrence of PBC and CBC was prospectively studied in 639 women ≥ 30 years (330 BRCA1 mutation carriers, 117 BRCA2 mutation carriers, and 192 HBOC women) who were enrolled in a breast/ovarian cancer surveillance program at the Rotterdam Family Cancer Clinic. Women with a history of BC without recurrent disease were eligible if BC treatment did not involve adjuvant systemic therapy. Demographics and follow-up (FU) information up to December 31, 2007, were extracted from the medical records. Ninety-eight BRCA1 mutation carriers, 33 BRCA2 mutation carriers and 15 HBOC women eventually underwent RRSO. Results were analyzed separately for women being at risk for PBC (n=489) and for CBC (n=164). The effect of RRSO on the incidence of BC was analyzed using a Cox proportional hazards model in which RRSO was modeled as a time-dependent covariate.
 Results: During a mean FU of 5.5 years, RRSO was associated with a reduction in BC risk of 48% (HR=0.52; 95% CI, 0.26-1.02; p=0.058) versus 81% (HR=0.19; 95% CI, 0.02-1.95; p=0.161) in BRCA1 and BRCA2 mutation carriers, respectively. In BRCA1 mutation carriers, PBC was reduced by 74% (HR=0.26; 95% CI, 0.08-0.89; p=0.032), and CBC by 29% (HR=0.71; 95% CI, 0.23-2.16; p=0.544). In BRCA2 mutation carriers no cases of PBC occurred after RRSO (HR=0,00; 95% CI, not estimable), while 1 CBC was diagnosed (HR=0.25; 95% CI, 0.01-5.62; p=0.379). In HBOC women no BC cases were observed after RRSO.
 Conclusions: RRSO is associated with a BC risk reduction in both BRCA1 and BRCA2 mutation carriers. The risk reductive effect is more pronounced regarding PBC as compared to CBC in BRCA1 mutation carriers. Although a similar trend is suggested for BRCA2 mutation carriers, larger numbers and longer FU are needed to draw firm conclusions. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 504.