Association of the colorectal CpG island methylator phenotype with molecular features, risk factors, and family history.

BACKGROUND: The CpG island methylator phenotype (CIMP) represents a subset of colorectal cancers characterized by widespread aberrant DNA hypermethylation at select CpG islands. The risk factors and environmental exposures contributing to etiologic heterogeneity between CIMP and non-CIMP tumors are not known. METHODS: We measured the CIMP status of 3,119 primary population-based colorectal cancer tumors from the multinational Colon Cancer Family Registry. Etiologic heterogeneity was assessed by a case-case study comparing risk factor frequency of colorectal cancer cases with CIMP and non-CIMP tumors using logistic regression to estimate the case-case odds ratio (ccOR). RESULTS: We found associations between tumor CIMP status and MSI-H (ccOR = 7.6), BRAF V600E mutation (ccOR = 59.8), proximal tumor site (ccOR = 9; all P < 0.0001), female sex [ccOR = 1.8; 95% confidence interval (CI), 1.5-2.1], older age (ccOR = 4.0 comparing over 70 years vs. under 50; 95% CI, 3.0-5.5), and family history of CRC (ccOR = 0.6; 95% CI, 0.5-0.7). While use of NSAIDs varied by tumor CIMP status for both males and females (P = 0.0001 and P = 0.02, respectively), use of multivitamin or calcium supplements did not. Only for female colorectal cancer was CIMP status associated with increased pack-years of smoking (Ptrend < 0.001) and body mass index (BMI; Ptrend = 0.03). CONCLUSIONS: The frequency of several colorectal cancer risk factors varied by CIMP status, and the associations of smoking and obesity with tumor subtype were evident only for females. IMPACT: Differences in the associations of a unique DNA methylation-based subgroup of colorectal cancer with important lifestyle and environmental exposures increase understanding of the molecular pathologic epidemiology of this heavily methylated subset of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 24(3); 512-9. ©2015 AACR.

11q13 is a susceptibility locus for hormone receptor positive breast cancer.

A recent two-stage genome-wide association study (GWAS) identified five novel breast cancer susceptibility loci on chromosomes 9, 10, and 11. To provide more reliable estimates of the relative risk associated with these loci and investigate possible heterogeneity by subtype of breast cancer, we genotyped the variants rs2380205, rs1011970, rs704010, rs614367, and rs10995190 in 39 studies from the Breast Cancer Association Consortium (BCAC), involving 49,608 cases and 48,772 controls of predominantly European ancestry. Four of the variants showed clear evidence of association (P ≤ 3 × 10(-9) ) and weak evidence was observed for rs2380205 (P = 0.06). The strongest evidence was obtained for rs614367, located on 11q13 (per-allele odds ratio 1.21, P = 4 × 10(-39) ). The association for rs614367 was specific to estrogen receptor (ER)-positive disease and strongest for ER plus progesterone receptor (PR)-positive breast cancer, whereas the associations for the other three loci did not differ by tumor subtype.

Ascending the learning curve--MSI testing experience of a six-laboratory consortium.

According to recently published guidelines, microsatellite instability (MSI) testing of colorectal cancers may be clinically indicated on a significant proportion of all colorectal tumors. To date, nothing has been published regarding the reproducibility of MSI testing between laboratories. We present MSI quality control activities experience of a six center multinational consortium, as laboratories developed competency with MSI testing and interpretation. The aim of this paper is to share lessons learned and to describe the final concordance rates in scoring MSI markers within this consortium.

Association between biallelic and monoallelic germline MYH gene mutations and colorectal cancer risk.

The MutY human homologue (MYH) gene encodes a member of the base excision repair pathway that is involved in repairing oxidative damage to DNA. Two germline MYH gene mutations that result in Myh proteins containing amino acid substitutions Y165C and G382D (hereafter called the Y165C and G382D mutations) are associated with adenomatous poly-posis and colorectal cancer among patients from several European poly-posis registries. We used a population-based series of 1238 colorectal cancer patients and 1255 healthy control subjects from Ontario, Canada, to examine the risk of colorectal cancer among biallelic and monoallelic germline MYH Y165C and G382D mutation carriers. The entire MYH gene coding region was screened in all MYH Y165C and G382D mutation carriers. Compared with noncarriers, biallelic and monoallelic germline MYH gene mutation carriers had an increased risk of colorectal cancer and were more likely to have first-or second-degree relatives with colorectal cancer (relative risk = 1.54, 95% confidence interval = 1.10 to 2.16). The increased risk of colorectal cancer in biallelic and monoallelic MYH gene mutation carriers was not consistently associated with the development of multiple adenomatous polyps. Loss of heterozygosity in at least one of four loci in MYH was detected in eight (47%) of 17 colorectal tumors from monoallelic MYH gene mutation carriers but in only two (20%) of 10 colorectal tumors from biallelic MYH gene mutation carriers. These two MYH gene mutations may account for a substantial fraction of hereditary colorectal cancer.