Limited influence of germline genetic variation on all-cause mortality in women with early onset breast cancer: evidence from gene-based tests, single-marker regression, and whole-genome prediction.

PURPOSE: Women diagnosed with breast cancer have heterogeneous survival outcomes that cannot be fully explained by known prognostic factors, and germline variation is a plausible but unconfirmed risk factor. METHODS: We used three approaches to test the hypothesis that germline variation drives some differences in survival: mortality loci identification, tumor aggressiveness loci identification, and whole-genome prediction. The 2954 study participants were women diagnosed with breast cancer before age 50, with a median follow-up of 15 years who were genotyped on an exome array. We first searched for loci in gene regions that were associated with all-cause mortality. We next searched for loci in gene regions associated with five histopathological characteristics related to tumor aggressiveness. Last, we also predicted 10-year all-cause mortality on a subset of 1903 participants (3,245,343 variants after imputation) using whole-genome prediction methods. RESULTS: No risk loci for mortality or tumor aggressiveness were identified. This null result persisted when restricting to women with estrogen receptor-positive tumors, when examining suggestive loci in an independent study, and when restricting to previously published risk loci. Additionally, the whole-genome prediction model also found no evidence to support an association. CONCLUSION: Despite multiple complementary approaches, our study found no evidence that mortality in women with early onset breast cancer is influenced by germline variation.

Common genetic variants and modification of penetrance of BRCA2-associated breast cancer.

The considerable uncertainty regarding cancer risks associated with inherited mutations of BRCA2 is due to unknown factors. To investigate whether common genetic variants modify penetrance for BRCA2 mutation carriers, we undertook a two-staged genome-wide association study in BRCA2 mutation carriers. In stage 1 using the Affymetrix 6.0 platform, 592,163 filtered SNPs genotyped were available on 899 young (<40 years) affected and 804 unaffected carriers of European ancestry. Associations were evaluated using a survival-based score test adjusted for familial correlations and stratified by country of the study and BRCA2*6174delT mutation status. The genomic inflation factor (λ) was 1.011. The stage 1 association analysis revealed multiple variants associated with breast cancer risk: 3 SNPs had p-values<10(-5) and 39 SNPs had p-values<10(-4). These variants included several previously associated with sporadic breast cancer risk and two novel loci on chromosome 20 (rs311499) and chromosome 10 (rs16917302). The chromosome 10 locus was in ZNF365, which contains another variant that has recently been associated with breast cancer in an independent study of unselected cases. In stage 2, the top 85 loci from stage 1 were genotyped in 1,264 cases and 1,222 controls. Hazard ratios (HR) and 95% confidence intervals (CI) for stage 1 and 2 were combined and estimated using a retrospective likelihood approach, stratified by country of residence and the most common mutation, BRCA2*6174delT. The combined per allele HR of the minor allele for the novel loci rs16917302 was 0.75 (95% CI 0.66-0.86, ) and for rs311499 was 0.72 (95% CI 0.61-0.85, ). FGFR2 rs2981575 had the strongest association with breast cancer risk (per allele HR = 1.28, 95% CI 1.18-1.39, ). These results indicate that SNPs that modify BRCA2 penetrance identified by an agnostic approach thus far are limited to variants that also modify risk of sporadic BRCA2 wild-type breast cancer.

Elevated levels of proliferating and recently migrated tumor-associated macrophages confer increased aggressiveness and worse outcomes in breast cancer.

PURPOSE: Macrophages play a major role in inflammatory processes and have been associated with poor prognosis in a variety of cancers, including breast cancer. Previously, we investigated the relationship of a subset of tumor-associated macrophages (PCNA(+) TAMs) with clinicopathologic characteristics of breast cancer. We reported that high PCNA(+) TAM counts were associated with hormone receptor (HR)-negative, high-grade tumors and early recurrence. To further understand the significance of elevated PCNA(+) TAMs and the functionality of TAMs, we examined the expression of S100A8/S100A9 with the antibody Mac387. The heterodimeric S100A8/S100A9 complex plays a role in inflammation and is increased in several cancer types. METHODS: We performed immunohistochemistry using the Mac387 antibody on 367 invasive human breast cancer cases. Results were compared to previous PCNA(+) TAM counts and were correlated with patient outcomes adjusting for HR status and histologic grade. RESULTS: Like PCNA(+) TAMs, high Mac387 counts were associated with HR negativity, high tumor grade, younger age, and decreased recurrence-free survival. Mac387, however, appears to identify both a subset of macrophages and a subset of tumor cells. The concordance between Mac387 and PCNA(+) TAM counts was low and cases that had both high Mac387 and high PCNA(+) TAMs counts had a stronger association with early recurrence. CONCLUSIONS: The presence of high numbers of PCNA(+) TAMs and Mac387-positive cells in breast cancers with poor outcomes may implicate a subset of TAMs in breast cancer pathogenesis, and may ultimately serve to develop potential cellular targets for therapeutic interventions.

Germline Variation and Breast Cancer Incidence: A Gene-Based Association Study and Whole-Genome Prediction of Early-Onset Breast Cancer.

Background: Although germline genetics influences breast cancer incidence, published research only explains approximately half of the expected association. Moreover, the accuracy of prediction models remains low. For women who develop breast cancer early, the genetic architecture is less established.Methods: To identify loci associated with early-onset breast cancer, gene-based tests were carried out using exome array data from 3,479 women with breast cancer diagnosed before age 50 and 973 age-matched controls. Replication was undertaken in a population that developed breast cancer at all ages of onset.Results: Three gene regions were associated with breast cancer incidence: FGFR2 (P = 1.23 × 10-5; replication P < 1.00 × 10-6), NEK10 (P = 3.57 × 10-4; replication P < 1.00 × 10-6), and SIVA1 (P = 5.49 × 10-4; replication P < 1.00 × 10-6). Of the 151 gene regions reported in previous literature, 19 (12.5%) showed evidence of association (P < 0.05) with the risk of early-onset breast cancer in the early-onset population. To predict incidence, whole-genome prediction was implemented on a subset of 3,076 participants who were additionally genotyped on a genome wide array. The whole-genome prediction outperformed a polygenic risk score [AUC, 0.636; 95% confidence interval (CI), 0.614-0.659 compared with 0.601; 95% CI, 0.578-0.623], and when combined with known epidemiologic risk factors, the AUC rose to 0.662 (95% CI, 0.640-0.684).Conclusions: This research supports a role for variation within FGFR2 and NEK10 in breast cancer incidence, and suggests SIVA1 as a novel risk locus.Impact: This analysis supports a shared genetic etiology between women with early- and late-onset breast cancer, and suggests whole-genome data can improve risk assessment. Cancer Epidemiol Biomarkers Prev; 27(9); 1057-64. ©2018 AACR.

Disruption of the expected positive correlation between breast tumor size and lymph node status in BRCA1-related breast carcinoma.

BACKGROUND: A positive correlation between breast tumor size and the number of axillary lymph nodes containing tumor is well established. It has been reported that patients with BRCA1-related breast carcinoma are more likely than patients with nonhereditary breast carcinoma to have negative lymph node status. Therefore, the authors questioned whether the known positive correlation between tumor size and lymph node status also was present in women with BRCA1-related breast carcinomas. METHODS: The relation between the greatest dimension of the resected breast tumor (size) and the presence of positive axillary lymph nodes (expressed as a percentage of all lymph nodes examined) was evaluated in 1555 women with invasive breast carcinoma who were ascertained at 10 centers in North America between 1975 and 1997. There were 276 BRCA1 mutation carriers, 136 BRCA2 carriers, and 1143 women without a known mutation (208 BRCA1/BRCA2 noncarriers and 935 untested women). Patients were stratified according to tumor size, and odds ratios were estimated for the presence of positive lymph nodes with increasing tumor size. RESULTS: A highly significant positive correlation between tumor size and the frequency of positive axillary lymph nodes was seen for BRCA1/BRCA2 noncarriers, for BRCA2 carriers, and for untested women (overall P < 0.0001 for each). In contrast, there was no clear correlation between tumor size and positive lymph node status in BRCA1 carriers (overall P = 0.20). CONCLUSIONS: The relation between tumor size and lymph node status in patients with breast carcinoma appears to be different in BRCA1 carriers compared with BRCA2 carriers and noncarriers. These findings have important implications for estimating the route of metastatic spread and for evaluating the effectiveness of early diagnosis in patients with BRCA1-related breast carcinoma.