No abstract

Genome-wide association studies have identified breast cancer risk variants in over 150 genomic regions, but the mechanisms underlying risk remain largely unknown. These regions were explored by combining association analysis with in silico genomic feature annotations. We defined 205 independent risk-associated signals with the set of credible causal variants (CCVs) in each one. In parallel, we used a Bayesian approach (PAINTOR) that combines genetic association, linkage disequilibrium, and enriched genomic features to determine variants with high posterior probabilities of being causal. Potentially causal variants were significantly over-represented in active gene regulatory regions and transcription factor binding sites. We applied our INQUSIT Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Breast cancer susceptibility variants frequently show heterogeneity in associations by tumor subtype. To identify novel loci, we performed a genome-wide association study (GWAS) including 133,384 breast cancer cases and 113,789 controls, plus 18,908 BRCA1 mutation carriers (9,414 with breast cancer) of European ancestry, using both standard and novel methodologies that account for underlying tumor heterogeneity by estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status and tumor grade. We identified 32 novel susceptibility loci (P<5.0x10 -8 ), 15 of which showed evidence for associations with at least one tumor feature (false discovery rate <0.05). Five loci showed associations (P<0.05) in opposite directions between luminal-and non-luminal subtypes. In-silico analyses showed these five loci contained cell-specific enhancers that differed between normal luminal and basal mammary cells. The genetic correlations between five intrinsic-like subtypes ranged from 0.35 to 0.80. The proportion of genome-wide chip heritability explained by all known susceptibility loci was 37.6% for triple-negative and 54.2% for luminal A-like disease. These findings provide an improved understanding of genetic predisposition to breast cancer subtypes and will inform the development of subtype-specific polygenic risk scores.

BackgroundIn healthy BRCA1/2 mutation carriers, bilateral risk-reducing mastectomy (BRRM) strongly reduces the risk of developing breast cancer (BC); however, no clear survival benefit of BRRM over BC surveillance has been reported yet.MethodsIn this Dutch multicenter cohort study, we used multivariable Cox models with BRRM as a time-dependent covariable to estimate the associations between BRRM and the overall and BC-specific mortality rates, separately for BRCA1 and BRCA2 mutation carriers.ResultsDuring a mean follow-up of 10.3 years, 722 out of 1712 BRCA1 (42%) and 406 out of 1145 BRCA2 (35%) mutation carriers underwent BRRM. For BRCA1 mutation carriers, we observed 52 deaths (20 from BC) in the surveillance group, and 10 deaths (one from BC) after BRRM. The hazard ratios were 0.40 (95% CI 0.20–0.90) for overall mortality and 0.06 (95% CI 0.01–0.46) for BC-specific mortality. BC-specific survival at age 65 was 93% for surveillance and 99.7% for BRRM. For BRCA2 mutation carriers, we observed 29 deaths (7 from BC) in the surveillance group, and 4 deaths (no BC) after BRRM. The hazard ratio for overall mortality was 0.45 (95% CI 0.15–1.36). BC-specific survival at age 65 was 98% for surveillance and 100% for BRRM.ConclusionBRRM was associated with lower mortality than surveillance for BRCA1 mutation carriers, but for BRCA2 mutation carriers, BRRM may lead to similar BC-specific survival as surveillance. Our findings support a more individualized counseling based on BRCA mutation type.Electronic supplementary materialThe online version of this article (10.1007/s10549-019-05345-2) contains supplementary material, which is available to authorized users.

Background: BRCA1/2 mutation carriers and women from a hereditary breast(/ovarian) cancer family have a highly increased risk of developing breast cancer (BC). Prophylactic mastectomy (PM) results in the greatest BC risk reduction. Long-term data on the efficacy and sequels of PM are scarce.Methods: From 358 high-risk women (including 236 BRCA1/2 carriers) undergoing PM between 1994 and 2004, relevant data on the occurrence of BC in relation to PM, complications in relation to breast reconstruction (BR), mutation status, age at PM and preoperative imaging examination results were extracted from the medical records, and analyzed separately for women without (unaffected, n = 177) and with a BC history (affected, n = 181).Results: No primary BCs occurred after PM (median follow-up 4.5 years). In one previously unaffected woman, metastatic BC was detected almost 4 years after PM (primary BC not found). Median age at PM was younger in unaffected women (P < .001), affected women more frequently were 50% risk carriers (P < .001). Unexpected (pre)malignant changes at PM were found in 3% of the patients (in 5 affected, and 5 unaffected women, respectively). In 49.6% of the women opting for BR one or more complications were registered, totaling 215 complications, leading to 153 surgical interventions (71%). Complications were mainly related to cosmetic outcome (36%) and capsular formation (24%).Conclusions: The risk of developing a primary BC after PM remains low after longer follow-up. Preoperative imaging and careful histological examination is warranted because of potential unexpected (pre)malignant findings. The high complication rate after breast reconstruction mainly concerns cosmetic issues.