BRCA1 BRCA2 mutational spectrum in the Middle East, North Africa, and Southern Europe is not well characterized. The unique history and cultural practices characterizing these regions, often involving consanguinity and inbreeding, plausibly led to the accumulation of population-specific founder pathogenic sequence variants (PSVs). To determine recurring BRCA PSVs in these locales, a search in PUBMED, EMBASE, BIC, and CIMBA was carried out combined with outreach to researchers from the relevant countries for unpublished data. We identified 232 PSVs in BRCA1 and 239 in BRCA2 in 25 of 33 countries surveyed. Common PSVs that were detected in four or more countries were c.5266dup (p.Gln1756Profs), c.181T>G (p.Cys61Gly), c.68_69del (p.Glu23Valfs), c.5030_5033del (p.Thr1677Ilefs), c.4327C>T (p.Arg1443Ter), c.5251C>T (p.Arg1751Ter), c.1016dup (p.Val340Glyfs), c.3700_3704del (p.Val1234Glnfs), c.4065_4068del (p.Asn1355Lysfs), c.1504_1508del (p.Leu502Alafs), c.843_846del (p.Ser282Tyrfs), c.798_799del (p.Ser267Lysfs), and c.3607C>T (p.Arg1203Ter) in BRCA1 and c.2808_2811del (p.Ala938Profs), c.5722_5723del (p.Leu1908Argfs), c.9097dup (p.Thr3033Asnfs), c.1310_1313del (p. p.Lys437Ilefs), and c.5946del (p.Ser1982Argfs) for BRCA2. Notably, some mutations (e.g., p.Asn257Lysfs (c.771_775del)) were observed in unrelated populations. Thus, seemingly genotyping recurring BRCA PSVs in specific populations may provide first pass BRCA genotyping platform.

Hormone receptor expression is a known positive prognostic and predictive factor in breast cancer; however, limited evidence exists on its impact on prognosis of young patients harboring BRCA pathogenic variant (PV). This international, multicenter, retrospective cohort study included young patients (≤40 years) diagnosed with invasive breast cancer and harboring germline PV in BRCA genes. We investigated the impact of hormone receptor status on clinical behavior and outcomes of breast cancer. Outcomes of interest (disease-free survival [DFS], breast cancer specific survival [BCSS] and overall survival [OS]) were first investigated according to hormone receptors expression (positive vs. negative), and then according to breast cancer subtype (luminal A-like vs. luminal B-like vs. triple-negative vs. HER2-positive breast cancer). From 78 centers worldwide, 4,709 BRCA carriers were included, of whom 2,143 (45.5%) had hormone receptor-positive and 2,566 (54.5%) hormone receptor-negative breast cancer. Median follow-up was 7.9 years. The rate of distant recurrences was higher in patients with hormone receptor-positive disease (13.1% vs. 9.6%, p<0.001), while the rate of second primary breast cancer was lower (9.1% vs. 14.7%, p<0.001) compared to patients with hormone receptor-negative disease. The 8-years DFS was 65.8% and 63.4% in patients with hormone receptor-positive and negative disease, respectively. The hazard ratio of hormone receptor-positive vs. negative disease changed over time for DFS, BCSS, and OS (p<0.05 for interactions of hormone receptor status and survival time). Patients with luminal A-like breast cancer had the worst long-term prognosis in terms of DFS compared to all the other subgroups (8-years DFS: 60.8% in luminal A-like vs. 63.5% in triple-negative vs. 65.5% in HER2-positive and 69.7% in luminal B-like subtype). In young BRCA carriers, differences in recurrence pattern and second primary breast cancer among hormone receptor-positive vs. negative disease warrants consideration in counseling patients on treatment, follow-up, and risk-reducing surgery.