Breast cancer risk in BRCA1/2 mutation carriers and non-carriers under prospective intensified surveillance
Menée en Allemagne à partir de données de deux cohortes portant sur 4 380 patientes atteintes d'un premier cancer du sein (âge médian : 39 ans) et sur 2 993 patientes atteintes d'un cancer du sein controlatéral (âge médian : 42 ans), cette étude prospective analyse le risque de développer la maladie selon la présence de mutations BRCA1/2, chez des femmes participant à un programme de surveillance intensifiée
Comparably little is known about breast cancer risks in women from families tested negative for BRCA1/2 mutations despite an indicative family history, as opposed to BRCA1/2 mutation carriers. We determined the age-dependent risks of first and contralateral breast cancer (FBC, CBC) both in non-carriers and carriers of BRCA1/2 mutations, who participated in an intensified breast imaging surveillance program. The study was conducted between January 1, 2005, and September 30, 2017, at 12 university centers of the German Consortium for Hereditary Breast and Ovarian Cancer. Two cohorts were prospectively followed up for incident FBC (n=4,380; 16,398 person-years, median baseline age: 39 years) and CBC (n=2,993; 10,090 person-years, median baseline age: 42 years). Cumulative FBC risk at age 60 was 61.8% (95%CI 52.8-70.9%) for BRCA1 mutation carriers, 43.2% (95%CI 32.1-56.3%) for BRCA2 mutation carriers, and 15.7% (95%CI 11.9-20.4%) for non-carriers. FBC risks were significantly higher than in the general population, with incidence rate ratios of 23.9 (95%CI 18.9-29.8) for BRCA1 mutation carriers, 13.5 (95%CI 9.2-19.1) for BRCA2 mutation carriers, and 4.9 (95%CI 3.8-6.3) for BRCA1/2 non-carriers. Cumulative CBC risk 10 years after FBC was 25.1% (95%CI 19.6-31.9%) for BRCA1 mutation carriers, 6.6% (95%CI 3.4-12.5%) for BRCA2 mutation carriers, and 3.6% (95%CI 2.2-5.7%) for non-carriers. Contralateral breast cancer risk in non-carriers was similar to women with unilateral BC from the general population. Further studies are needed to confirm whether less intensified surveillance is justified in women from BRCA1/2 negative families with elevated risk. This article is protected by copyright. All rights reserved.