Stratification of women according to their risk of breast cancer based on polygenic risk scores (PRSs) could improve screening and prevention strategies. Our aim was to develop PRSs, optimized for prediction of estrogen receptor (ER)-specific disease, from the largest available genome-wide association dataset and to empirically validate the PRSs in prospective studies. The development dataset comprised 94,075 case subjects and 75,017 control subjects of European ancestry from 69 studies, divided into training and validation sets. Samples were genotyped using genome-wide arrays, and single-nucleotide polymorphisms (SNPs) were selected by stepwise regression or lasso penalized regression. The best performing PRSs were validated in an independent test set comprising 11,428 case subjects and 18,323 control subjects from 10 prospective studies and 190,040 women from UK Biobank (3,215 incident breast cancers). For the best PRSs (313 SNPs), the odds ratio for overall disease per 1 standard deviation in ten prospective studies was 1.61 (95%CI: 1.57–1.65) with area under receiver-operator curve (AUC) = 0.630 (95%CI: 0.628–0.651). The lifetime risk of overall breast cancer in the top centile of the PRSs was 32.6%. Compared with women in the middle quintile, those in the highest 1% of risk had 4.37- and 2.78-fold risks, and those in the lowest 1% of risk had 0.16- and 0.27-fold risks, of developing ER-positive and ER-negative disease, respectively. Goodness-of-fit tests indicated that this PRS was well calibrated and predicts disease risk accurately in the tails of the distribution. This PRS is a powerful and reliable predictor of breast cancer risk that may improve breast cancer prevention programs.

PURPOSE Recent studies demonstrate that addition of neoadjuvant (NA) carboplatin (Cb) to anthracycline/taxane chemotherapy improves pathological complete response (pCR) in triple negative breast cancer (TNBC). Effectiveness of anthracycline-free, platinum combinations in TNBC is not well known. Here we report efficacy of NA carboplatin + docetaxel (CbD) in TNBC. PATIENTS AND METHODS The study population includes 190 patients with stage I-III TNBC treated uniformly on two independent prospective cohorts. All patients were prescribed NA chemotherapy regimen of Cb (AUC 6) + D (75mg/m2) given every 21 days × 6 cycles. Pathological complete response (pCR: no evidence of invasive tumor in the breast and axilla) and Residual Cancer Burden (RCB) were evaluated. RESULTS Among 190 patients, median tumor size was 35mm, 52% Lymph Node positive and 16% had germline BRCA1/2 mutation. The overall pCR and RCB 0+1 rates were 55% and 68%, respectively. pCR in patients with BRCA associated and wild-type TNBC were 59% and 56%, respectively (p=0.83). On multivariable analysis stage III disease was the only factor associated with a lower likelihood of achieving a pCR. 21% and 7% of patients, respectively, experienced at least one grade 3 or 4 adverse event. CONCLUSION The CbD regimen was well tolerated and yielded high pCR rates in both BRCA associated and wildtype TNBC. These results are comparable to pCR achieved with addition of Cb to anthracycline-taxane chemotherapy. Our study adds to the existing data on the efficacy of platinum agents in TNBC and supports further exploration of the CbD regimen in randomized studies.

Genome-wide association studies (GWAS) have identified more than 170 breast cancer susceptibility loci. Here we hypothesize that some risk-associated variants might act in non-breast tissues, specifically adipose tissue and immune cells from blood and spleen. Using expression quantitative trait loci (eQTL) reported in these tissues, we identify 26 previously unreported, likely target genes of overall breast cancer risk variants, and 17 for estrogen receptor (ER)-negative breast cancer, several with a known immune function. We determine the directional effect of gene expression on disease risk measured based on single and multiple eQTL. In addition, using a gene-based test of association that considers eQTL from multiple tissues, we identify seven (and four) regions with variants associated with overall (and ER-negative) breast cancer risk, which were not reported in previous GWAS. Further investigation of the function of the implicated genes in breast and immune cells may provide insights into the etiology of breast cancer.