Skewed X chromosome inactivation and early-onset breast cancer.

BACKGROUND: Skewed X chromosome inactivation may be more common in women with epithelial ovarian cancer and early-onset breast cancer. We tested this hypothesis in a group of 235 breast cancer patients and 253 controls (mean age 45.8 years) from a larger population based case control study. METHODS: We measured X chromosome inactivation with the AR gene assay in lymphocyte DNA digested with the methylation specific enzyme HpaII. We judged skewness using an adjusted measure (relative to the undigested sample) with a cut point of 75%, and an unadjusted measure where skewed was defined as > 90% of the signal from one allele in the HpaII digested sample. RESULTS: There were no significant differences in any of the skewing measures between cases and controls. Using the adjusted skewing measure among pre-menopausal subjects under the age of 50, 14% of cases versus 11% of controls were skewed, OR = 1.2, 95% CI 0.6 to 2.3; using the unadjusted measure, OR = 0.9, 95% CI 0.4 to 2.0. CONCLUSIONS: While we cannot rule out a subtle difference of approximately twofold or less, we have failed to find a significant difference in the prevalence of skewed X chromosome inactivation in younger women with breast cancer compared to controls.

Prospective risk of cancer in CDKN2A germline mutation carriers.

BACKGROUND: The CDKN2A gene is the major known high-risk melanoma susceptibility gene. Susceptibility to other cancers has also been suggested. However, most studies examining the risks of other cancers classified individuals according to the family's CDKN2A mutation rather than determining individual mutation status. For non-population-based studies, risks could also be biased because of cancer occurrence prior to family ascertainment. METHODS: We examined the risk of non-melanoma cancer in 117 mutation-positive and 136 mutation-negative members from 15 families that had at least two first degree relatives with melanoma and CDKN2A mutations restricting the analysis to the period after the families were ascertained (that is, the prospective period) and using individual mutation data. The families have been followed prospectively for 4-26 years starting in the 1970s. RESULTS: Overall, there was no significant association for mutation-negative subjects (Obs/Exp = 0.3, 95% confidence interval (CI) 0.0 to 1.2) although this group had only two observed cancers. In contrast, mutation-positive subjects had a significantly increased risk for all cancers combined (Obs/Exp = 12/5.5 = 2.2, 95% CI 1.1 to 3.8) primarily because of digestive system tumours, particularly pancreatic cancer. No other organ systems or individual tumour sites showed significantly increased risks. CONCLUSIONS: Differences in CDKN2A-non-melanoma cancer associations across studies may result from variation in genetic backgrounds, insufficient follow up, misclassification of mutation carriers, or the presence of other genetic and/or environmental risk factors in both CDKN2A mutation carriers and non-carriers. Larger sample sizes, prospective follow up, and individual mutation data will be required to understand these differences.

XPD gene polymorphism and host characteristics in the association with cutaneous malignant melanoma risk.

We recently reported an association between low DNA repair capacity, measured through the host-cell reactivation assay, and melanoma risk in subjects with dysplastic naevi or low tanning ability. We investigated the genetic basis for these findings by analysing the Asp312Asn and Lys751Gln polymorphisms of the XPD (ERCC2) DNA repair gene in the same subjects. Similar to our previous report, no significant association between XPD polymorphisms and melanoma risk was found in 176 melanoma cases and 177 controls (odds ratio (OR)=1.5, 95% confidence interval (CI)=0.9-2.5 for 312Asn; OR=1.3, 95% CI=0.8-2.1 for 751Gln, adjusted for age, gender, dysplastic naevi and pigmentation characteristics). However, XPD variants were associated with increased risk in older (>50 years) subjects (OR=3.4, 95% CI=1.6-7.3 for 312Asn; OR=2.3, 95% CI=1.1-4.9 for 751Gln). The 751Gln allele was associated with elevated melanoma risk among subjects without dysplastic naevi (OR=2.6, 95% CI=1.1-6.4). Subjects with low tanning ability and XPD variants exhibited a nonsignificant increase of melanoma risk (OR=2.3, 95% CI=0.7-7.0 for 312Asn; OR=3.0, 95% CI=1.0-8.8 for 751Gln). DNA repair capacity was slightly decreased in subjects carrying 751Gln alleles. XPD variants may modify melanoma risk in subjects with specific host characteristics, such as older age, lack of dysplastic naevi or low tanning ability.

Population attributes affecting the prevalence of BRCA mutation carriers in epithelial ovarian cancer cases in israel.

OBJECTIVE: The objective was to evaluate the prevalence of BRCA1/2 mutations in selected categories of ovarian cancer patients in Israel. METHODS: Blood samples and specimens of ovarian tumors were obtained in the course of a national case control study of women with ovarian cancer in Israel. Eight hundred ninety-six patients with epithelial ovarian cancer, 40 cases with nonepithelial ovarian cancer, and 68 with primary peritoneal cancer were tested for the BRCA mutations. Analysis of the three common BRCA mutations in Israel (185delAG, 5382insC in BRCA1, and 6174delT in BRCA2) was done using a multiplex polymerase chain reaction assay. A multivariate logistic regression model was used to assess the association of mutation carrier status and other factors (age, origin, family history, and clinical variables). RESULTS: Of the 779 invasive epithelial ovarian cancer cases, 29.4% were mutation carriers. The prevalence of the mutations was higher among women below age 60 and in more advanced cases. The prevalence was low in mucinous tumors. There was almost a twofold excess of mutations among women with positive family history (45.7%), but still 26.5% of the family history negative cases were carriers. As expected, we found a higher rate of mutation carriers among the Ashkenazi group (34.2%) and 55% among Ashkenazi women with positive family history. No subjects born in North Africa were mutation positive. CONCLUSION: BRCA mutations are strongly associated with ovarian cancer and they are present in variable rates in distinct age, ethnic, and histopathologic categories.

Frequency of BRCA mutations in primary peritoneal carcinoma in Israeli Jewish women.

OBJECTIVE: The aim of the present study was to compare demographic and clinical characteristics of primary peritoneal carcinoma (PPC) to ovarian carcinoma (OvC) with regard to BRCA mutation frequencies. METHODS: Incident cases of histologically confirmed cancer of the ovary or peritoneum diagnosed in Israeli Jewish women between March 1, 1994, and June 30, 1999, were identified within the framework of an ongoing nationwide epidemiological study of these neoplasms in Israel. The present study comprises 609 (81.5% of 747) Jewish women with epithelial stage III-IV OvC and 68 (77.3% of 88) Jewish women with PPC who were genetically tested for the BRCA mutations. Data from each patient were collected by the aid of a prestructured questionnaire and medical records. Blood samples or tumor tissue was tested for the 185delAG and 5382insC mutations in BRCA1 and the 6174delT mutations in BRCA2. RESULTS: A carrier rate of 28% of any BRCA 1/2 mutation was observed among the PPC group and of 30% among the invasive stage III-IV OvC. No differences were found between PPC and OvC neither in the overall distribution of BRCA1/2 mutation carrier rates nor according to type of mutation, age, ethnic origin, and histologic subtype. Among women with a positive family history, a higher rate of mutation carriers was observed in the PPC group compared to the OvC group (72.7 vs 43.8%, respectively, P = 0.07). CONCLUSIONS: The similar frequency distribution of BRCA1/2 mutations in PPC and OvC observed in the present study indicates that these mutations may predispose to PPC as well and that this neoplasm is part of the hereditary breast-ovarian cancer syndrome.

Effect of BRCA mutations on the length of survival in epithelial ovarian tumors.

PURPOSE: To study the role of BRCA mutations in ovarian cancer survival. PATIENTS AND METHODS: Blood samples and specimens of ovarian tumors (whenever blood samples were not available) at the time of the primary surgery were obtained in the course of a nationwide case-control study of women with ovarian cancer in Israel. The three common BRCA mutations in Israel (185delAG, 5382insC, and 6174delT) were analyzed with a multiplex polymerase chain reaction to amplify the exons containing the three mutations using fluor-labeled primers in a single reaction. Because each mutation is a small insertion or deletion, they can be detected as length polymorphisms. Patients were followed for up to 5 years (range, 20 to 64 months). Statistical analysis was performed using the Kaplan-Meier method and the log-rank test. Stepwise Cox regression analysis was used for determination of independent prognostic factors. RESULTS: This report is based on 896 blood or tumor specimens analyzed for the presence of the BRCA mutations. Of these, 234 women (26.1%) were found to be positive. A significant difference in survival pattern was found between BRCA1/BRCA2 carriers and noncarriers among the women with invasive ovarian cancer (median survival, 53.4 months v. 37.8 months; 3-year survival, 65.8% v. 51.9%, respectively). These differences were independent of age at diagnosis or stage of the disease. CONCLUSION: Our data indicate that the survival of patients with ovarian cancer is affected by BRCA germline mutation, at least in the early years after diagnosis.

A single nucleotide polymorphism in the 5' untranslated region of RAD51 and risk of cancer among BRCA1/2 mutation carriers.

RAD51 colocalizes with both BRCA1 and BRCA2, and genetic variants in RAD51 would be candidate BRCA1/2 modifiers. We searched for RAD51 polymorphisms by sequencing 20 individuals. We compared the polymorphism allele frequencies between female BRCA1/2 mutation carriers with and without breast or ovarian cancer and between population-based ovarian cancer cases with BRCA1/2 mutations to cases and controls without mutations. We discovered two single nucleotide polymorphisms (SNPs) at positions 135 g-->c and 172 g-->t of the 5' untranslated region. In an initial group of BRCA1/2 mutation carriers, 14 (21%) of 67 breast cancer cases carried a "c" allele at RAD51:135 g-->c, whereas 8 (7%) of 119 women without breast cancer carried this allele. In a second set of 466 mutation carriers from three centers, the association of RAD51:135 g-->c with breast cancer risk was not confirmed. Analyses restricted to the 216 BRCA2 mutation carriers, however, showed a statistically significant association of the 135 "c" allele with the risk of breast cancer (adjusted odds ratio, 3.2; 95% confidence limit, 1.4-40). BRCA1/2 mutation carriers with ovarian cancer were only about one half as likely to carry the RAD51:135 g-->c SNP. Analysis of the RAD51:135 g-->c SNP in 738 subjects from an Israeli ovarian cancer case-control study was consistent with a lower risk of ovarian cancer among BRCA1/2 mutation carriers with the "c" allele. We have identified a RAD51 5' untranslated region SNP that may be associated with an increased risk of breast cancer and a lower risk of ovarian cancer among BRCA2 mutation carriers. The biochemical basis of this risk modifier is currently unknown.

A common founder for the V126D CDKN2A mutation in seven North American melanoma-prone families.

One of the most common melanoma-related CDKN2A mutations reported in North America is the V126D mutation. We examined nine markers surrounding CDKN2A in three American and four Canadian families carrying the V126D mutation. All seven families had a haplotype consistent with a common ancestor/founder for this mutation. In addition, the mutation appears to have originated 34-52 generations ago (1-LOD-unit support interval 13-98 generations).

Parity, oral contraceptives, and the risk of ovarian cancer among carriers and noncarriers of a BRCA1 or BRCA2 mutation.

BACKGROUND: Multiparity and the use of oral contraceptives reduce the risk of ovarian cancer, but their effects on this risk in women with a BRCA1 or BRCA2 mutation are unclear. METHODS: We conducted a population-based case-control study of ovarian cancer among Jewish women in Israel. Women were tested for the two founder mutations in BRCA1 and the one founder mutation in BRCA2 that are known to be common among Jews. We estimated the effects of parity and oral-contraceptive use on the risk of ovarian cancer in carriers and noncarriers in separate analyses that included all control women, who did not have ovarian cancer. RESULTS: Of 751 controls who underwent mutation analysis, 13 (1.7 percent) had a BRCA1 or BRCA2 mutation, whereas 244 of 840 women with ovarian cancer (29.0 percent) had a BRCA1 or BRCA2 mutation. Overall, each additional birth and each additional year of use of oral contraceptives were found to lower the risk of ovarian cancer, as expected. Additional births were protective in separate analyses of carriers and noncarriers, but oral-contraceptive use appeared to reduce the risk only in noncarriers; among carriers, the reduction in the odds of ovarian cancer was 12 percent per birth (95 percent confidence interval, 2.3 to 21 percent) and 0.2 percent per year of oral-contraceptive use (-4.9 to 5.0 percent). CONCLUSIONS: The risk of ovarian cancer among carriers of a BRCA1 or BRCA2 mutation decreases with each birth but not with increased duration of use of oral contraceptives. These data suggest that it is premature to use oral contraceptives for the chemoprevention of ovarian cancer in carriers of such mutations.

Patients with double primary tumors in the breast and ovary- clinical characteristics and BRCA1-2 mutations status.

OBJECTIVE: The aim of this study was to define the prevalence, clinical characteristics, and BRCA1-2 mutation carrier status of ovarian cancer (OvC) patients with a previous primary malignancy in the breast (PPMBr). METHODS: The study population comprised 1240 consecutive Jewish Israeli women with pathologically confirmed epithelial OvC diagnosed between March 1, 1994, and December 31, 1997. Demographic and clinical data were obtained from medical files and from a detailed questionnaire taken through a nationwide epidemiological case-control study on OvC. Blood samples and tumor tissues were collected for analysis of the three predominant germline BRCA1-2 Jewish founder mutations (185delAG, 5382insC, and 6174delT). RESULTS: Fifty nine (4.7%) patients with OvC had a PPMBr. The median age at diagnosis of OvC was 60 years. The mean interval between the two diagnoses was 104 months (range 0-363 months). In the majority of the patients (n = 53), the diagnosis of breast cancer (BrC) preceded the OvC by more than 1 year. The ovarian tumors were diagnosed in 47% of the cases following investigation of patients' symptoms. In 41%, diagnosis was made as a consequence of check-up exams performed during the routine follow-up of BrC survivors. Patients with PPMBr were more likely to present with FIGO ovarian stage III-IV, compared to women with solitary OvC (73% vs 60. 3%, P < 0.05), and less likely to have borderline tumors (3.4% vs 17. 9%, P = 0.007). Family history of OvC/BrC was recorded in 26% of this group of patients compared to 10.5% among patients with solitary OvC (P = 0.003). Patients with PPMBr had an exceptionally high prevalence of BRCA1-2 mutations (57%), irrespective of family history. CONCLUSIONS: Patients with PPMBr present with more advanced disease and invasive-type epithelial ovarian tumors when compared to cases associated with solitary OvC. The rate of BRCA1-2 mutations in Jewish women with OvC who had PPMBr is at least twice as high as in Jewish women with OvC as the solitary disease.

Psychosocial factors predicting BRCA1/BRCA2 testing decisions in members of hereditary breast and ovarian cancer families.

Although BRCA1/2 testing has increasingly entered clinical practice, much is to be learned about the most effective ways to provide counseling to persons potentially interested in receiving test results. The purpose of this study was to identify factors affecting genetic testing decisions in a cohort of hereditary breast and ovarian cancer (HBOC) families presented with the choice to undergo testing. Relatives in these families are known to carry BRCA1 or BRCA2 mutations. Sociodemographics, personality traits, and family functioning were self-assessed using validated psychometric instruments at baseline. Among 172 individuals who participated in pretest education and counseling, 135 (78%) chose to undergo genetic testing and 37 (22%) chose not to be tested. Individuals who chose to undergo genetic testing were more likely to be older (> or =40 years), to have lower levels of optimism, and to report higher levels of cohesiveness in their families. A better understanding of factors that influence interest in predictive testing may help to inform the counseling that occurs prior to genetic testing.

Genotype-phenotype relationships in U.S. melanoma-prone families with CDKN2A and CDK4 mutations.

BACKGROUND: Two genes have been implicated in the development of cutaneous malignant melanoma (CMM). CDK4 (the gene encoding cyclin-dependent kinase 4, an oncogene) has exhibited germline mutations found in only three melanoma-prone families to date. CDKN2A is a tumor suppressor gene that encodes p16 (which inhibits activity of the cyclin D1-CDK4 complex) with germline mutations detected in 10%-25% of melanoma-prone families, some of whom are also prone to pancreatic cancer. METHODS: We compared 104 CMM patients from 17 CDKN2A families and 12 CMM case subjects from two CDK4 families. We used nonparametric statistics to test for differences in median age at first CMM diagnosis, numbers of CMMs, and numbers of nevi. The three recurrent mutations were haplotyped. All P values were two-sided. RESULTS: The median age at CMM diagnosis (P =.70) and the median numbers of CMMs (P =.73) did not differ between CMM case subjects from CDKN2A versus CDK4 families. Assessment of CMM case subjects from CDKN2A families with and without pancreatic cancer revealed no statistically significant differences in median age at diagnosis (P =.80) or in tumor number (P =.24). There was, however, a statistically significant difference in age-adjusted median numbers of nevi (P =.004), and CMM case subjects from CDKN2A families without pancreatic cancer had greater numbers of nevi. Recurrent CDKN2A mutations were a change from valine to aspartic acid at codon 126 (n = 3) and from glycine to tryptophan at codon 101 (n = 3). Six CDKN2A families had pancreatic cancer. Both CDK4 families carried a mutation resulting in an arginine-to-cysteine substitution at codon 24. Analyses of recurrent CDKN2A and CDK4 mutations suggested common haplotypes. CONCLUSIONS: The recurrent CDKN2A mutations were observed in families with and without pancreatic cancer, which suggests that other factors may be involved in the development of pancreatic cancer. Despite hypothetical differences in the mechanisms of action between CDKN2A and CDK4, clinical factors were indistinguishable between CMM case subjects from CDKN2A versus CDK4 families.

A single genetic origin for the G101W CDKN2A mutation in 20 melanoma-prone families.

Germline mutations within the coding region of CDKN2A have been observed in affected members of melanoma-prone families. G101W is the most common CDKN2A missense mutation identified to date. It has been reported in several families from around the world, with a particularly high occurrence in France and Italy. Given the frequency of this mutation, we were interested in determining whether the mutation resulted from a single origin or represented a mutational hotspot in the CDKN2A gene. In addition, given the geographical distribution of the mutation, we examined the date of origination of the mutation and its migratory spread. We examined 10 families from Italy, 4 families from the United States, and 6 families from France with the G101W mutation. The following eight markers were employed for the haplotype analysis: IFNA, D9S736, D9S1749, D9S942, D9S1748, D9S1604, D9S171, and D9S126. Our findings showed no significant evidence for mutational heterogeneity, suggesting that all studied families derived from a single ancestral haplotype on which the mutation arose. Using maximum-likelihood methods, we estimated the mutation to have arisen 97 generations ago (1-LOD-unit support interval 70-133 generations) providing some explanation for the wide geographical spread of this common mutation, particularly in southwestern Europe. The presence of a founder mutation in a defined geographic area can facilitate carrier detection and genetic counseling and can provide an opportunity to study disease penetrance and the effect of environmental factors on the background of a common genetic susceptibility.

Histopathologic features of ovaries at increased risk for carcinoma. A case-control analysis.

In this study, the pathogenesis of ovarian carcinoma was investigated by performing a masked histopathologic comparison of benign ovaries removed from 61 women predicted to be at increased risk for developing carcinoma (cases) with ovaries removed from 121 women without known predisposing conditions (controls). The cases included 26 women who had a unilateral invasive carcinoma and 35 women undergoing prophylactic oophorectomy for a family history of ovarian cancer. As predicted by previously developed models, epithelial inclusion cysts were identified more frequently with advancing age in both cases and controls. However, the mean and maximum number of cysts per slide in a woman were not increased among cases. Surface epithelial "atypia," a designation based on a composite impression of multiple features, was found in 13% of cases compared with 3% of controls (relative risk 7.1; 95% confidence interval, 1.9 to 26.1), but this result was based on small numbers. None of the other histologic features examined was found more often in cases following age-adjustment. Reexamination of sections with well-preserved surface epithelium or inclusion cysts under oil immersion demonstrated several differences in the detection of specific features between cases and controls and increased detection of "atypia" among cases, but none of these findings reached statistical significance. It is concluded that there may be subtle differences in the surface epithelium of ovaries predisposed to developing cancer as compared with controls, but these changes are difficult to identify reliably with light microscopy. Future etiologic studies should attempt to optimize specific handling and include molecular studies and epidemiologic analyses.

The prevalence of common BRCA1 and BRCA2 mutations among Ashkenazi Jews.

Three founder mutations in the cancer-associated genes BRCA1 and BRCA2 occur frequently enough among Ashkenazi Jews to warrant consideration of genetic testing outside the setting of high-risk families with multiple cases of breast or ovarian cancer. We estimated the prevalence of these founder mutations in BRCA1 and BRCA2 in the general population of Ashkenazi Jews according to age at testing, personal cancer history, and family cancer history. We compared the results of anonymous genetic testing of blood samples obtained in a survey of >5,000 Jewish participants from the Washington, DC, area with personal and family cancer histories obtained from questionnaires completed by the participants. In all subgroups defined by age and cancer history, fewer mutations were found in this community sample than in clinical series studied to date. For example, 11 (10%) of 109 Jewish women who had been given a diagnosis of breast cancer in their forties carried one of the mutations. The most important predictor of mutation status was a previous diagnosis of breast or ovarian cancer. In men and in women never given a diagnosis of cancer, family history of breast cancer before age 50 years was the strongest predictor. As interest in genetic testing for BRCA1 and BRCA2 in the Jewish community broadens, community-based estimates such as these help guide those seeking and those offering such testing. Even with accurate estimates of the likelihood of carrying a mutation and the likelihood of developing cancer if a mutation is detected, the most vexing clinical problems remain.

Survival after breast cancer in Ashkenazi Jewish BRCA1 and BRCA2 mutation carriers.

BACKGROUND: Studies of survival following breast and ovarian cancers in BRCA1 and/or BRCA2 mutation carriers have yielded conflicting results. We undertook an analysis of a community-based study of Ashkenazi Jews to investigate the effect of three founder mutations in BRCA1 and BRCA2 on survival among patients with breast or ovarian cancer. METHODS: We collected blood samples and questionnaire data from 5318 Ashkenazi Jewish volunteers. The blood samples were tested for 185delAG (two nucleotide deletion) and 5382insC (single nucleotide insertion) mutations in BRCA1 and the 6174delT (single nucleotide deletion) mutation in BRCA2. To estimate survival differences in the affected relatives according to their BRCA1 and/or BRCA2 mutation carrier status, we devised and applied a novel extension of the kin-cohort method. RESULTS: Fifty mutation carriers reported that 58 of their first-degree relatives had been diagnosed with breast cancer and 10 with ovarian cancer; 907 noncarriers reported 979 first-degree relatives with breast cancer and 116 with ovarian cancer. Kaplan-Meier estimates of median survival after breast cancer were 16 years (95% confidence interval [CI] = 11-40) in the relatives of carriers and 18 years (95% CI = 15-22) in the relatives of noncarriers, a difference that was not statistically significant (two-sided P = .87). There was also no difference in survival times among the 126 first-degree relatives with ovarian cancer. We found no survival difference between patients with breast or ovarian cancer who were inferred carriers of BRCA1 and/or BRCA2 mutations and noncarriers. CONCLUSIONS: Carriers of BRCA1 and BRCA2 mutations appeared to have neither better nor worse survival prognosis.

Population-based study of risk of breast cancer in carriers of BRCA2 mutation.

BACKGROUND: Estimates of an 80-90% risk of breast cancer for carriers of germline mutations in the BRCA1 and BRCA2 genes are based on studies of families at high risk of breast cancer. Risk estimates for a population are possible if the mutation status of a representative sample of that population can be assessed. In Iceland, one common founder BRCA2 mutation occurs in 0.6% of the population. Iceland has a population-based cancer registry and a large collection of pedigrees, and estimation of cancer risk in mutation carriers is therefore possible. METHODS: We studied 575 breast-cancer patients, 541 women and 34 men unselected for family history of breast cancer. Data on cancer in first-degree relatives were available from the cancer registry. Risk of cancer was estimated by comparing the history of cancer in first-degree relatives of carriers and non-carriers. FINDINGS: 56 (10.4%) of the 541 women and 13 (38%) of the 34 men carried the 999del5 mutation. The estimated risk of breast cancer at age 50 for all female carriers of the 999del5 mutation was 17.0% (95% CI 9.1-25.9) and 37.2% (22.4-53.9) at age 70. INTERPRETATION: The results of our population-based study show that the mean risk of breast cancer in carriers of mutation in BRCA2 is lower than previously suggested. Individual risk assessment will, however, have to take account of family history.