Richard A. DiCioccio

Multiple Loci With Different Cancer Specificities Within the 8q24 Gene Desert

Recent studies based on genome-wide association, linkage, and admixture scan analysis have reported associations of various genetic variants in 8q24 with susceptibility to breast, prostate, and colorectal cancer. This locus lies within a 1.18-Mb region that contains no known genes but is bounded at its centromeric end by FAM84B and at its telomeric end by c-MYC, two candidate cancer susceptibility genes. To investigate the associations of specific loci within 8q24 with specific cancers, we genotyped the nine previously reported cancer-associated single-nucleotide polymorphisms across the region in four case-control sets of prostate (1854 case subjects and 1894 control subjects), breast (2270 case subjects and 2280 control subjects), colorectal (2299 case subjects and 2284 control subjects), and ovarian (1975 case subjects and 3411 control subjects) cancer. Five different haplotype blocks within this gene desert were specifically associated with risks of different cancers. One block was solely associated with risk of breast cancer, three others were associated solely with the risk of prostate cancer, and a fifth was associated with the risk of prostate, colorectal, and ovarian cancer, but not breast cancer. We conclude that there are at least five separate functional variants in this region.

A genome-wide association study identifies a new ovarian cancer susceptibility locus on 9p22.2

Epithelial ovarian cancer has a major heritable component, but the known susceptibility genes explain less than half the excess familial risk. We performed a genome-wide association study (GWAS) to identify common ovarian cancer susceptibility alleles. We evaluated 507,094 SNPs genotyped in 1,817 cases and 2,353 controls from the UK and ∼2 million imputed SNPs. We genotyped the 22,790 top ranked SNPs in 4,274 cases and 4,809 controls of European ancestry from Europe, USA and Australia. We identified 12 SNPs at 9p22 associated with disease risk (P < 10−8). The most significant SNP (rs3814113; P = 2.5 × 10−17) was genotyped in a further 2,670 ovarian cancer cases and 4,668 controls, confirming its association (combined data odds ratio (OR) = 0.82, 95% confidence interval (CI) 0.79–0.86, Ptrend = 5.1 × 10−19). The association differs by histological subtype, being strongest for serous ovarian cancers (OR 0.77, 95% CI 0.73–0.81, Ptrend = 4.1 × 10−21).

Oral contraceptive use and ovarian cancer risk among carriers of BRCA1 or BRCA2 mutations

Women with mutations of the genes BRCA1 or BRCA2 are at increased risk of ovarian cancer. Oral contraceptives protect against ovarian cancer in general, but it is not known whether they protect against the disease in carriers of these mutations. We obtained self-reported lifetime histories of oral contraceptive use from 451 women who carried mutations of BRCA1 or BRCA2. We used conditional logistic regression to estimate the odds ratios associated with oral contraceptive use, comparing the histories of 147 women with ovarian cancer (cases) to those of 304 women without ovarian cancer (controls) who were matched to cases on year of birth, country of residence and gene (BRCA1 vs BRCA2). Reference ages for controls had to exceed the ages at diagnosis of their matched cases. After adjusting for parity, the odds-ratio for ovarian cancer associated with use of oral contraceptives for at least 1 year was 0.85 (95 percent confidence interval, 0.53–1.36). The risk decreased by 5% (1–9%) with each year of use (P for trend=0.01). Use for 6 or more years was associated with an odds-ratio of 0.62 (0.35–1.09). These data support the hypothesis that long-term oral contraceptive use reduces the risk of ovarian cancer among women who carry mutations of BRCA1 or BRCA2.

Polymorphisms in DNA repair genes and epithelial ovarian cancer risk

DNA repair gene polymorphisms and mutations are known to influence cancer risk. We studied whether polymorphisms in DNA double strand break (DSB) repair genes are associated with epithelial ovarian cancer (EOC) risk. Up to 1,600 cases and 4,241 controls from 4 separate genetic association studies from 3 countries were genotyped for 13 single nucleotide polymorphisms (SNP) in 6 genes (BRCA1, NBS1, RAD51, RAD52, XRCC2 and XRCC3) involved in homologous recombination of DNA double strand breaks. Genotype specific risks were estimated as odds ratios (OR) by unconditional logistic regression. No association was detected between EOC risk and BRCA1 Q356R, BRCA1 P871L, RAD51 g135c, RAD51 g172t, RAD52 c2259t, NBS1 L34L, NBS1 E185Q, NBS1 A399A, NBS1 P672P, XRCC2 g4324c, XRCC2 c41657t and XRCC3 T241M. The XRCC2 R188H polymorphism was associated with a modest reduction in EOC risk: OR for heterozygotes was 0.8 (95% confidence interval [CI] = 0.7–1.0) and for rare homozygotes 0.3 (0.1–0.9). The XRCC3 a4541g polymorphism, situated in the 5′UTR, and the intronic XRCC3 a17893g polymorphism were not associated with EOC risk in general, but when the serous EOC subset only was analysed, the OR for heterozygotes for a4541g was 1.0 (0.9–1.2) and for the rare homozygotes 0.5 (0.3–0.9). For the XRCC3 a17893g polymorphism, the OR for the heterozygotes and the rare homozygotes were 0.8 (0.7–0.9) and 0.9 (0.7–1.2), respectively. In our study, some polymorphisms in XRCC2 and XRCC3 genes were associated with EOC risk. Further research on the role of these genes on epithelial ovarian cancer is warranted.

Tagging Single Nucleotide Polymorphisms in Cell Cycle Control Genes and Susceptibility to Invasive Epithelial Ovarian Cancer

High-risk susceptibility genes explain <40% of the excess risk of familial ovarian cancer. Therefore, other ovarian cancer susceptibility genes are likely to exist. We have used a single nucleotide polymorphism (SNP)-tagging approach to evaluate common variants in 13 genes involved in cell cycle control-CCND1, CCND2, CCND3, CCNE1, CDK2, CDK4, CDK6, CDKN1A, CDKN1B, CDKN2A, CDKN2B, CDKN2C, and CDKN2D-and risk of invasive epithelial ovarian cancer. We used a two-stage, multicenter, case-control study. In stage 1, 88 SNPs that tag common variation in these genes were genotyped in three studies from the United Kingdom, United States, and Denmark ( approximately 1,500 cases and 2,500 controls). Genotype frequencies in cases and controls were compared using logistic regression. In stage 2, eight other studies from Australia, Poland, and the United States ( approximately 2,000 cases and approximately 3,200 controls) were genotyped for the five most significant SNPs from stage 1. No SNP was significant in the stage 2 data alone. Using the combined stages 1 and 2 data set, CDKN2A rs3731257 and CDKN1B rs2066827 were associated with disease risk (unadjusted P trend = 0.008 and 0.036, respectively), but these were not significant after adjusting for multiple testing. Carrying the minor allele of these SNPs was found to be associated with reduced risk [OR, 0.91 (0.85-0.98) for rs3731257; and OR, 0.93 (0.87-0.995) for rs2066827]. In conclusion, we have found evidence that a single tagged SNP in both the CDKN2A and CDKN1B genes may be associated with reduced ovarian cancer risk. This study highlights the need for multicenter collaborations for genetic association studies.

Histopathology, FIGO stage, and BRCA mutation status of ovarian cancers from the Gilda Radner Familial Ovarian Cancer Registry.

Studies of the histopathology of ovarian cancer arising in patients with germline mutations in BRCA1 or BRCA2 have shown inconsistent findings. We analyzed the large number of tumors from women enrolled in the Gilda Radner Familial Ovarian Cancer Registry for correlations between histopathology and BRCA mutation status. Histopathology slides and reports were reviewed for histology, grade, and stage for cancers of the ovary or peritoneum in 220 women from 126 Gilda Radner Familial Ovarian Cancer Registry families. At least one affected member of each family was analyzed for mutations in the BRCA1 and BRCA2 genes, and tumors from mutation-positive families were compared with those from mutation-negative families. Of 70 patients from 38 BRCA1-positive families, 69 had epithelial ovarian carcinoma and one had a dysgerminoma. Fifteen of 16 patients from nine BRCA2-positive families had epithelial ovarian cancer, and one had a primary peritoneal cancer. Of 134 patients from 79 BRCA-negative families, 118 had epithelial ovarian carcinoma, 11 had ovarian borderline tumors, three had nonepithelial tumors, and two had primary peritoneal carcinoma. There were fewer grade 1 (p < 0.001) and stage I (p = 0.005) cancers in patients from BRCA-positive families than in patients from BRCA-negative families. Neither mucinous nor borderline tumors were found in the BRCA-positive families. In conclusion, ovarian cancers arising in women from BRCA-positive families are more likely to be high-grade and have extraovarian spread than tumors arising in women from BRCA-negative families. Borderline and mucinous tumors do not appear to be part of the phenotype of families with germline mutations in the BRCA genes.

Consortium analysis of 7 candidate SNPs for ovarian cancer.

The Ovarian Cancer Association Consortium selected 7 candidate single nucleotide polymorphisms (SNPs), for which there is evidence from previous studies of an association with variation in ovarian cancer or breast cancer risks. The SNPs selected for analysis were F31I (rs2273535) in AURKA, N372H (rs144848) in BRCA2, rs2854344 in intron 17 of RB1, rs2811712 5′ flanking CDKN2A, rs523349 in the 3′ UTR of SRD5A2, D302H (rs1045485) in CASP8 and L10P (rs1982073) in TGFB1. Fourteen studies genotyped 4,624 invasive epithelial ovarian cancer cases and 8,113 controls of white non‐Hispanic origin. A marginally significant association was found for RB1 when all studies were included [ordinal odds ratio (OR) 0.88 (95% confidence interval (CI) 0.79–1.00) p = 0.041 and dominant OR 0.87 (95% CI 0.76–0.98) p = 0.025]; when the studies that originally suggested an association were excluded, the result was suggestive although no longer statistically significant (ordinal OR 0.92, 95% CI 0.79–1.06). This SNP has also been shown to have an association with decreased risk in breast cancer. There was a suggestion of an association for AURKA, when one study that caused significant study heterogeneity was excluded [ordinal OR 1.10 (95% CI 1.01–1.20) p = 0.027; dominant OR 1.12 (95% CI 1.01–1.24) p = 0.03]. The other 5 SNPs in BRCA2, CDKN2A, SRD5A2, CASP8 and TGFB1 showed no association with ovarian cancer risk; given the large sample size, these results can also be considered to be informative. These null results for SNPs identified from relatively large initial studies shows the importance of replicating associations by a consortium approach.

Histopathology of familial ovarian tumors in women from families with and without germline BRCA1 mutations

Breast cancers from patients with germline BRCA1 mutations show characteristic histopathologic features. However, similar studies of BRCA1-associated ovarian cancers have reported inconsistent findings. Interobserver differences in histopathologic classification are a significant source of variation, and most studies have obtained histopathologic information from pathology reports rather than from review of histopathology slides. We therefore reviewed the histopathology slides and pathology reports to determine histologic type, grade, and stage for cancers of the ovary or peritoneum in 217 women from 126 families enrolled in the Gilda Radner Familial Ovarian Cancer Registry. Peripheral blood DNA from at least 1 affected member of each family was analyzed for BRCA1 mutations, and tumors from BRCA1 mutation-positive families were compared with those from BRCA1-negative families. Of 66 patients from 36 BRCA1-positive families, 64 had ovarian carcinoma, 1 had an ovarian carcinoma in situ, and 1 had a dysgerminoma. Of 151 patients from 90 BRCA1-negative families, 135 had ovarian carcinoma, 10 had ovarian borderline tumors, 3 had ovarian sex cord/stromal tumors, and 3 had primary peritoneal carcinoma. There were fewer grade 1 (P <.001) and stage I (P =.10) cancers in patients from BRCA1-positive families than in patients from BRCA1-negative families. Neither mucinous nor borderline tumors were found in the BRCA1-positive families. Ovarian cancers arising in women from BRCA1-positive families are more likely to be high grade and nonmucinous than cancers arising in women from BRCA1-negative families. The absence of borderline tumors in patients from BRCA1-positive families adds to accumulating evidence that BRCA1 mutations do not play a role in the development of these tumors. HUM PATHOL 31:1420-1424.

Aberrations of TACC1 and TACC3 are associated with ovarian cancer

BackgroundDysregulation of the human Transforming Acidic Coiled Coil (TACC) genes is thought to be important in the development and progression of multiple myeloma, breast and gastric cancer. Recent, large-scale genomic analysis and Serial Analysis of Gene Expression data suggest that TACC1 and TACC3 may also be involved in the etiology of ovarian tumors from both familial and sporadic cases. Therefore, the aim of this study was to determine the occurrence of alterations of these TACCs in ovarian cancer.MethodsDetection and scoring of TACC1 and TACC3 expression was performed by immunohistochemical analysis of the T-BO-1 tissue/tumor microarray slide from the Cooperative Human Tissue Network, Tissue Array Research Program (TARP) of the National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. Tumors were categorized as either positive (greater than 10% of cells staining) or negative. Statistical analysis was performed using Fishers exact test and p < 0.05 (single comparisons), and p < 0.02 (multiple comparisons) were considered to be significant. Transgenomics WAVE high performance liquid chromatography (dHPLC) was used to pre-screen the TACC3 gene in constitutional DNA from ovarian cancer patients and their unaffected relatives from 76 families from the Gilda Radner Familial Ovarian Cancer Registry. All variant patterns were then sequenced.ResultsThis study demonstrated absence of at least one or both TACC proteins in 78.5% (51/65) of ovarian tumors tested, with TACC3 loss observed in 67.7% of tumors. The distribution pattern of expression of the two TACC proteins was different, with TACC3 loss being more common in serous papillary carcinoma compared with clear cell carcinomas, while TACC1 staining was less frequent in endometroid than in serous papillary tumor cores. In addition, we identified two constitutional mutations in the TACC3 gene in patients with ovarian cancer from the Gilda Radner Familial Ovarian Cancer Registry. These patients had previously tested negative for mutations in known ovarian cancer predisposing genes.ConclusionWhen combined, our data suggest that aberrations of TACC genes, and TACC3 in particular, underlie a significant proportion of ovarian cancers. Thus, TACC3 could be a hitherto unknown endogenous factor that contributes to ovarian tumorigenesis.

Association Between Single-Nucleotide Polymorphisms in Hormone Metabolism and DNA Repair Genes and Epithelial Ovarian Cancer: Results from Two Australian Studies and an Additional Validation Set

Although some high-risk ovarian cancer genes have been identified, it is likely that common low penetrance alleles exist that confer some increase in ovarian cancer risk. We have genotyped nine putative functional single-nucleotide polymorphisms (SNP) in genes involved in steroid hormone synthesis (SRD5A2, CYP19A1, HSB17B1, and HSD17B4) and DNA repair (XRCC2, XRCC3, BRCA2, and RAD52) using two Australian ovarian cancer case-control studies, comprising a total of 1,466 cases and 1,821 controls of Caucasian origin. Genotype frequencies in cases and controls were compared using logistic regression. The only SNP we found to be associated with ovarian cancer risk in both of these two studies was SRD5A2 V89L (rs523349), which showed a significant trend of increasing risk per rare allele (P = 0.00002). We then genotyped another SNP in this gene (rs632148; r2 = 0.945 with V89L) in an attempt to validate this finding in an independent set of 1,479 cases and 2,452 controls from United Kingdom, United States, and Denmark. There was no association between rs632148 and ovarian cancer risk in the validation samples, and overall, there was no significant heterogeneity between the results of the five studies. Further analyses of SNPs in this gene are therefore warranted to determine whether SRD5A2 plays a role in ovarian cancer predisposition. (Cancer Epidemiol Biomarkers Prev 2007;16(12):2557–9)