The 6q22.33 locus and breast cancer susceptibility.

Recently, we identified a novel breast cancer susceptibility locus at 6q22.33 following a genome-wide association study in the Ashkenazi Jewish genetic isolate. To replicate these findings, we did a case-control association analysis on 6q22.33 (rs2180341) in an additional 487 Ashkenazi Jewish breast cancer cases and in an independent non-Jewish, predominantly European American, population of 1,466 breast cancer cases and 1,467 controls. We confirmed the 6q22.33 association with breast cancer risk in the replication cohorts [per-allele odds ratio (OR), 1.18; 95% confidence interval (95% CI), 1.04-1.33; P = 0.0083], with the strongest effect in the aggregate meta-analysis of 3,039 breast cancer cases and 2,616 Ashkenazi Jewish and non-Jewish controls (per-allele OR, 1.24; 95% CI, 1.13-1.36; P = 3.85 x 10(-7)). We also showed that the association was slightly stronger with estrogen receptor-positive tumors (per-allele OR, 1.35; 95% CI, 1.20-1.51; P = 2.2 x 10(-5)) compared with estrogen receptor-negative tumors (per-allele OR, 1.19; 95% CI, 0.97-1.47; P = 0.1). Furthermore, this study provides a novel insight into the functional significance of 6q22.33 in breast cancer susceptibility. Due to the stronger association of 6q22.33 with estrogen receptor-positive breast cancer, we examined the effect of candidate genes on estrogen receptor response elements. Upon transfection of overexpressed RNF146 in the MCF-7 breast cancer cell line, we observed diminished expression of an estrogen receptor response element reporter construct. This study confirms the association of 6q22.33 with breast cancer, with slightly stronger effect in estrogen receptor-positive tumors. Further functional studies of candidate genes are in progress, and a large replication analysis is being completed as part of an international consortium.

Selection of endometrial carcinomas for DNA mismatch repair protein immunohistochemistry using patient age and tumor morphology enhances detection of mismatch repair abnormalities.

Women with hereditary nonpolyposis colorectal cancer (HNPCC) have a high risk for endometrial cancer (EC) and frequently present with a gynecologic cancer as their first or sentinel malignancy. Identification of these patients is important given their personal and family risk for synchronous and metachronous tumors. The revised Bethesda Guidelines provide screening criteria for HNPCC in colorectal cancers. However, there are currently no such screening recommendations for women with endometrial carcinoma. We applied some of the colorectal cancer screening criteria, including age and tumor morphology, to endometrial endometrioid carcinoma. The purpose of this study was to describe patient and tumor characteristics and to assess the ability of these criteria to enhance detection of mismatch repair (MMR) deficiency, and hence HNPCC in EC. Immunohistochemistry (IHC) for DNA mismatch repair (IHC-MMR) proteins was performed in a defined subset of patients with EC. This included women younger than 50 years of age and women >or=50 years whose tumors showed morphologic features suggestive of MMR deficiency (TM-MMR). The extent of IHC-MMR in the older patient group was compared with that in a comparison group of EC >or=50 years that was previously analyzed for microsatellite instability status. Seventy-one patients met the selection criteria for IHC testing; 32 (45%) showed abnormal results. The rate of IHC abnormality in the younger group was approximately 30% with a nearly equal distribution of MLH1/PMS2 and MSH2/MSH6 abnormalities. In the older age group, TM-MMR triggered IHC analysis in 31 of 34 cases. Of these, 18 cases showed loss of IHC-MMR (58% of cases), 7 with loss of MSH2/MSH6. In contrast, the rate of microsatellite instability in the comparison group was only 21%. The IHC abnormal group showed more frequent tumor infiltrating lymphocytes, dedifferentiated EC, more tumors centered in the lower uterine segment, and more frequent synchronous clear cell carcinomas of the ovary than tumors with a normal immunophenotype. Although many of the patients with loss of IHC-MMR showed personal and/or family history (13 of 32) of HNPCC-associated tumors, most did not. Tumor morphology (TM-MMR) along with IHC-MMR enhances the detection of EC patients at risk of HNPCC.

Genome-wide association study provides evidence for a breast cancer risk locus at 6q22.33.

We performed a three-phase genome-wide association study (GWAS) using cases and controls from a genetically isolated population, Ashkenazi Jews (AJ), to identify loci associated with breast cancer risk. In the first phase, we compared allele frequencies of 150,080 SNPs in 249 high-risk, BRCA1/2 mutation-negative AJ familial cases and 299 cancer-free AJ controls using chi(2) and the Cochran-Armitage trend tests. In the second phase, we genotyped 343 SNPs from 123 regions most significantly associated from stage 1, including 4 SNPs from the FGFR2 region, in 950 consecutive AJ breast cancer cases and 979 age-matched AJ controls. We replicated major associations in a third independent set of 243 AJ cases and 187 controls. We obtained a significant allele P value of association with AJ breast cancer in the FGFR2 region (P = 1.5 x 10(-5), odds ratio (OR) 1.26, 95% confidence interval (CI) 1.13-1.40 at rs1078806 for all phases combined). In addition, we found a risk locus in a region of chromosome 6q22.33 (P = 2.9 x 10(-8), OR 1.41, 95% CI 1.25-1.59 at rs2180341). Using several SNPs at each implicated locus, we were able to verify associations and impute haplotypes. The major haplotype at the 6q22.33 locus conferred protection from disease, whereas the minor haplotype conferred risk. Candidate genes in the 6q22.33 region include ECHDC1, which encodes a protein involved in mitochondrial fatty acid oxidation, and also RNF146, which encodes a ubiquitin protein ligase, both known pathways in breast cancer pathogenesis.