Prevalence of BRCA1 and BRCA2 gene mutations in patients with early-onset breast cancer

Adjuvant therapy of the very young woman

Women under 35 or 40 with primary breast cancer have a poor prognosis independent of other factors [Albain K, Allred C, Clark G. Breast cancer outcome and predictors of outcome: are there age differentials? J Natl Cancer Inst Monogr 1994;35-42]. In some recent studies, however, age is not independent in multivariate analyses, which include gene signatures [Van De Vijver M, He YD, Van'T Veer L, et al. A gene-expression signature as a predictor of survival in breast cancer. N Engl J Med 2002;347:1999-2009.(132)]. Dissection of such molecular signatures may identify mechanisms, which can be targeted. Today, positive estrogen receptors identify women who require endocrine therapy, and HER2/neu positivity those who require herceptin and also benefit most from anthracyclines. Locoregional recurrences are also more common in younger women. Radiation boost therapy can reduce in-breast recurrence [Bartelink H, Horiot JC, Poortmans PM, Struikmans H, et al. Impact of radiation dose on local control, fibrosis and survival after breast conserving treatment: 10 year results of the EORTC trial 22881-10882. Br Cancer Res Treat 2006;100:S8-10]. There are also particular quality of life issues in young women, for whom fertility concerns and symptoms of premature menopause loom large. Some young women with lower risk may be candidates for endocrine therapy alone but it may be difficult to identify these with current prognostic and predictive factors. In the future more sophisticated molecular factors may identify those who require hormones alone, chemotherapy alone, newer biologic therapies, or combinations of these approaches.

Genetic factors leading to chronic Epstein-Barr virus infection and nasopharyngeal carcinoma in South East China: study design, methods and feasibility

Nasopharyngeal carcinoma (NPC) is a complex disease caused by a combination of Epstein-Barr virus chronic infection, the environment and host genes in a multi-step process of carcinogenesis. The identity of genetic factors involved in the development of chronic Epstein-Barr virus infection and NPC remains elusive, however. Here, we describe a two-phase, population-based, case-control study of Han Chinese from Guangxi province, where the NPC incidence rate rises to a high of 25-50 per 100,000 individuals. Phase I, powered to detect single gene associations, enrolled 984 subjects to determine feasibility, to develop infrastructure and logistics and to determine error rates in sample handling. A microsatellite screen of Phase I study participants, genotyped for 319 alleles from 34 microsatellites spanning an 18-megabase region of chromosome 4 (4p15.1-q12), previously implicated by a linkage analysis of familial NPC, found 14 alleles marginally associated with developing NPC or chronic immunoglobulin A production (p = 0.001-0.03). These associations lost significance after applying a correction for multiple tests. Although the present results await confirmation, the Phase II study population has tripled patient enrolment and has included environmental covariates, offering the potential to validate this and other genomic regions that influence the onset of NPC.

Characterization of familial non-BRCA1/2 breast tumors by loss of heterozygosity and immunophenotyping

PURPOSE

Since the identification of BRCA1 and BRCA2, there has been no major breast cancer susceptibility gene discovered by linkage analysis in breast cancer families. This has been attributed to the heterogeneous genetic basis for the families under study. Recent studies have indicated that breast tumors arising in women carrying a BRCA1 mutation have distinct histopathologic, immunophenotypic, and genetic features. To a lesser extent, this is also true for breast tumors from BRCA2 carriers. This indicates that it might be possible to decrease the genetic heterogeneity among families in which BRCA1 and BRCA2 have been excluded with high certainty (BRCAx families) if distinct subgroups of BRCAx-related breast tumors could be identified.

EXPERIMENTAL DESIGN

Loss of heterozygosity (LOH) analysis with at least one marker per chromosomal arm (65 markers) was used to characterize 100 breast tumors derived from 92 patients from 42 selected BRCAx families. In addition, the immunophenotype of 10 markers was compared with that of 31 BRCA1- and 21 BRCA2-related breast tumors.

RESULTS AND CONCLUSIONS

The BRCAx-related tumors were characterized by more frequent LOH at 22q relative to sporadic breast cancer (P < 0.02), and differed significantly from BRCA1- and BRCA2-related tumors in their positivity for Bcl2. However, cluster analyses of the combined data (LOH and immunohistochemistry) did not result in subgroups that would allow meaningful subclassification of the families. On chromosomes 2, 3, 6, 12, 13, 21, and 22, we found markers at which LOH occurred significantly more frequent among the tumors from patients belonging to a single family than expected on the basis of overall LOH frequencies. Nonetheless, linkage analysis with markers for the corresponding regions on chromosomes 12, 21, and 22 did not reveal significant logarithm of the odds.

Evaluation of models to predict BRCA germline mutations

The selection of candidates for BRCA germline mutation testing is an important clinical issue yet it remains a significant challenge. A number of risk prediction models have been developed to assist in pretest counselling. We have evaluated the performance and the inter-rater reliability of four of these models (BRCAPRO, Manchester, Penn and the Myriad-Frank). The four risk assessment models were applied to 380 pedigrees of families who had undergone BRCA1/2 mutation analysis. Sensitivity, specificity, positive and negative predictive values, likelihood ratios and area under the receiver operator characteristic (ROC) curve were calculated for each model. Using a greater than 10% probability threshold, the likelihood that a BRCA test result was positive in a mutation carrier compared to the likelihood that the same result would be expected in an individual without a BRCA mutation was 2.10 (95% confidence interval (CI) 1.66–2.67) for Penn, 1.74 (95% CI 1.48–2.04) for Myriad, 1.35 (95% CI 1.19–1.53) for Manchester and 1.68 (95% CI 1.39–2.03) for BRCAPRO. Application of these models, therefore, did not rule in BRCA mutation carrier status. Similar trends were observed for separate BRCA1/2 performance measures except BRCA2 assessment in the Penn model where the positive likelihood ratio was 5.93. The area under the ROC curve for each model was close to 0.75. In conclusion, the four models had very little impact on the pre-test probability of disease; there were significant clinical barriers to using some models and risk estimates varied between experts. Use of models for predicting BRCA mutation status is not currently justified for populations such as that evaluated in the current study.

Models of genetic susceptibility to breast cancer

One of the most important risk factors for breast cancer is family history of the disease, indicating that genetic factors are important determinants of breast cancer risk. A number of breast cancer susceptibility genes have been identified, the most important being BRCA1 and BRCA2. However, it is estimated that all the currently known breast cancer susceptibility genes accounts for less than 25% of the familial aggregation of breast cancer. In this paper, we review the evidence for other breast cancer susceptibility genes arising from twin studies, pedigree analysis and studies of phenotypes associated with breast cancer, and the progress towards finding other breast cancer susceptibility genes through linkage and association studies. Taken together, the available evidence indicates that susceptibility to breast cancer is mediated through variants in many genes, each conferring a moderate risk of the disease. Such a model of susceptibility has implications for both risk prediction and for future gene identification studies.

The GH1/IGF-1 axis polymorphisms and their impact on breast cancer development

The growth hormone 1/insulin-like growth factor-1 (GH1/IGF-1) axis plays an essential role in the development of the breast by regulating cell proliferation, differentiation and apoptosis. Imbalances within this axis lead to an aberrant signalling and recent research has focussed on the overexpression of these growth factors and their involvement in breast cancer development. The increased understanding of the molecular mechanisms and signalling pathways connected to the GH1/IGF-1 axis has provided important insights into aetiology, prevention and therapy for breast cancer. However, to identify the contribution of the GH1/IGF-1 signalling pathway to cancer risk still remains a challenge since the results of various studies are controversial. Here, we discuss the influence of low-penetrance polymorphisms in the genes along the GH1/IGF-1 axis and their impact on hormone levels and cancer risk, especially breast cancer. We point out what is known about the effects of the variants and show how the interaction of genetic variants affects breast cancer risk.

Selection bias influences reported contralateral breast cancer incidence and survival in high risk non-BRCA1/2 patients

PURPOSE

The results of studies comparing survival in familial and sporadic breast cancer (BC) are inconsistent. A higher incidence of contralateral breast cancer (CBC) has been reported in familial BC. Ascertainment bias may influence both the reported familial CBC and survival.

DESIGN

We assessed CBC incidence, distant disease free (DDFS) and overall survival (OS) in 327 BC patients who had > or =3 breast and/or ovarian cancers in the family but no BRCA1/2 gene mutation (non-BRCA1/2). They were matched to 327 sporadic controls for year and age at detection. To correct for ascertainment bias, we analyzed also separately the results (1) Of the 250 non-BRCA1/2 patients with DNA testing performed before diagnosis or within 2 years ('unselected') and (2) Of the 77 with testing > or =2 years after diagnosis (late-tested).

RESULTS

Median follow-up of non-BRCA1/2 patients was 6.1 yrs. Ten years CBC incidence was 11% in non-BRCA1/2 versus 6% in sporadic patients (p = 0.002). At multivariate analysis CBC incidence was increased in late-tested non-BRCA1/2 (HR 4.6; p = 0.001) not in 'unselected' (HR 1.8; p = 0.1). Increased CBC occurred in non-BRCA1/2 patients mainly before genetic testing, suggesting ascertainment bias. Tumors were < or =T1 in 62% of non-BRCA1/2 versus 50% of sporadic patients (p = 0.003), node-negative in 55% versus 52% respectively (p = 0.5). After correction for stage and therapy, OS did not differ between 'unselected' non-BRCA1/2 and sporadic patients (HR 0.8; p = 0.3), but was improved in late-tested non-BRCA1/2.

CONCLUSION

Overall survival and contralateral breast cancer incidence were similar in 'unselected' non-BRCA1/2- and sporadic patients. Reports of higher CBC incidence and better survival in non-BRCA1/2 patients may substantially be caused by DNA testing selection-bias.

Contribution of germline BRCA1 and BRCA2 sequence alterations to breast cancer in Northern India

Background

A large number of distinct mutations in the BRCA1 and BRCA2 genes have been reported worldwide, but little is known regarding the role of these inherited susceptibility genes in breast cancer risk among Indian women. We investigated the distribution and the nature of BRCA1 and BRCA2 germline mutations and polymorphisms in a cohort of 204 Indian breast cancer patients and 140 age-matched controls.

Method

Cases were selected with regard to early onset disease (≤40 years) and family history of breast and ovarian cancer. Two hundred four breast cancer cases along with 140 age-matched controls were analyzed for mutations. All coding regions and exon-intron boundaries of the BRCA1 and BRCA2 genes were screened by heteroduplex analysis followed by direct sequencing of detected variants.

Results

In total, 18 genetic alterations were identified. Three deleterious frame-shift mutations (185delAG in exon 2; 4184del4 and 3596del4 in exon 11) were identified in BRCA1, along with one missense mutation (K1667R), one 5'UTR alteration (22C>G), three intronic variants (IVS10-12delG, IVS13+2T>C, IVS7+38T>C) and one silent substitution (5154C>T). Similarly three pathogenic protein-truncating mutations (6376insAA in exon 11, 8576insC in exon19, and 9999delA in exon 27) along with one missense mutation (A2951T), four intronic alterations (IVS2+90T>A, IVS7+75A>T, IVS8+56C>T, IVS25+58insG) and one silent substitution (1593A>G) were identified in BRCA2. Four previously reported polymorphisms (K1183R, S1613G, and M1652I in BRCA1, and 7470A>G in BRCA2) were detected in both controls and breast cancer patients. Rare BRCA1/2 sequence alterations were observed in 15 out of 105 (14.2%) early-onset cases without family history and 11.7% (4/34) breast cancer cases with family history. Of these, six were pathogenic protein truncating mutations. In addition, several variants of uncertain clinical significance were identified. Among these are two missense variants, one alteration of a consensus splice donor sequence, and a variant that potentially disrupts translational initiation.

Conclusion

BRCA1 and BRCA2 mutations appear to account for a lower proportion of breast cancer patients at increased risk of harboring such mutations in Northern India (6/204, 2.9%) than has been reported in other populations. However, given the limited extent of reported family history among these patients, the observed mutation frequency is not dissimilar from that reported in other cohorts of early onset breast cancer patients. Several of the identified mutations are unique and novel to Indian patients.

Cancer incidence in first-degree relatives of a population-based set of cases of early-onset breast cancer

Reliable determination of familial risks for cancer is important for clinical counselling, cancer prevention and understanding cancer aetiology. Family-based gene identification efforts may be targeted if the risks are well characterised and the mode of inheritance is identified. Early-onset breast cancer in a family member is a risk indicator for cancer among first-degree relatives; however, the familial risk pattern has not been assessed fully in population-based incidence studies. We estimated the risks for cancers of the breast, ovary and other sites among the first-degree relatives of 8868 patients in whom breast cancer was diagnosed before they reached the age of 50 years (diagnosed during the period 1943-1999). Population registers and parish records were used to identify 31,235 first-degree relatives, who were followed up to 31 December 2002 for occurrence of cancer by linkage to the Danish Cancer Registry. The observed incidence rates were compared with national rates adjusted for age, sex and calendar period. Overall, 39% of the 674 cases of breast cancer and 43% of the 143 cases of ovarian cancer among relatives were associated with a diagnosis of early-onset breast cancer in a family member. Among relatives under 50 years of age, the proportions were 56% and 58%, respectively, and among relatives 50 years or above the proportions were approximately 30% and 10%. In addition, a slightly but significantly increased risk for cancer of the cervix uteri was observed among relatives, and among those under 50 years of age, we found significantly increased risks for cancers of the colon and gall-bladder. In conclusion, the excess risk for breast cancer in first-degree relatives is large and remains sizable in the subgroup of female relatives aged 50 years or older, and that mutations in BRCA1/2 seem to explain only half of breast cancer cases attributable to family history.

Family history of breast cancer and short-term effects of childbirths on breast cancer risk

The long-term protective effect of a pregnancy on breast cancer risk is preceded by a short-term adverse effect, possibly reflecting a promoting effect of pregnancy hormones. In the present study, we explore whether a family history of breast cancer modifies time-related effects of pregnancies, with special emphasis on the transient increase in risk of breast cancer shortly after birth. Our study cohort comprises 1,067,289 Norwegian women aged 20-74 years. The mean follow-up time was 18 years. Incidence rate ratios were estimated by Poisson regression analyses of person-years at risk. Of the 7,377 women diagnosed with breast cancer during follow-up, a total of 828 (11%) had a mother or a sister with breast cancer diagnosis. Women with a family history of breast cancer had a 2-3-fold higher risk of breast cancer than did women without any affected family member, highest for those with a relative diagnosed before they were 50 years. Similar to women without a familial excess risk, increasing parity was associated with an overall protective effect among women with a familial predisposition, regardless of age at diagnosis of the relative. Whereas women with no familial excess risk experienced a transient increase in risk mainly after late age births, women with a family history of breast cancer experienced an adverse effect of pregnancies also at younger ages. The present results give further support to the hypothesis that the adverse effect of a term birth can be explained by a promoting effect of pregnancy hormones.

Radiosensitivity in breast cancer assessed by the Comet and micronucleus assays

Spontaneous and radiation-induced genetic instability of peripheral blood mononuclear cells derived from unselected breast cancer (BC) patients (n=50) was examined using the single-cell gel electrophoresis (Comet) assay and a modified G2 micronucleus (MN) test. Cells from apparently healthy donors (n=16) and from cancer patients (n=9) with an adverse early skin reaction to radiotherapy (RT) served as references. Nonirradiated cells from the three tested groups exhibited similar baseline levels of DNA fragmentation assessed by the Comet assay. Likewise, the Comet analysis of in vitro irradiated (5 Gy) cells did not reveal any significant differences among the three groups with respect to the initial and residual DNA fragmentation, as well as the DNA repair kinetics. The G2 MN test showed that cells from cancer patients with an adverse skin reaction to RT displayed increased frequencies of both spontaneous and radiation-induced MN compared to healthy control or the group of unselected BC patients. Two patients from the latter group developed an increased early skin reaction to RT, which was associated with an increased initial DNA fragmentation in vitro only in one of them. Cells from the other BC patient exhibited a striking slope in the dose–response curve detected by the G2 MN test. We also found that previous RT strongly increased both spontaneous and in vitro radiation-induced MN levels, and to a lesser extent, the radiation-induced DNA damage assessed by the Comet assay. These data suggest that clinical radiation may provoke genetic instability and/or induce persistent DNA damage in normal cells of cancer patients, thus leading to increased levels of MN induction and DNA fragmentation after irradiation in vitro. Therefore, care has to be taken when blood samples collected postradiotherapeutically are used to assess the radiosensitivity of cancer patients.

Contralateral recurrence and prognostic factors in familial non-BRCA1/2-associated breast cancer

BACKGROUND

A higher incidence of contralateral breast cancer and ipsilateral recurrence has been reported in familial breast cancer than in sporadic cancer. This study investigated the influence of contralateral cancer and tumour stage on survival in patients with familial non-BRCA1/BRCA2-associated breast cancer.

METHODS

The incidences of contralateral breast cancer, ipsilateral recurrence, distant disease-free and overall survival were assessed in 327 patients from families with three or more breast and/or ovarian cancers, but no BRCA1 or BRCA2 gene mutation (familial non-BRCA1/2), and in 327 control subjects with sporadic breast cancer, matched for year and age at detection.

RESULTS

Mean follow-up was 7.3 years for patients with familial-non-BRCA1/2 cancers and 6.5 years for patients with sporadic breast cancer. Tumours were stage T1 or lower in 62.1 per cent of familial non-BRCA1/2 cancers versus 49.9 per cent in sporadic breast cancers (P = 0.003), and node negative in 55.8 versus 52.1 per cent, respectively (P = 0.477). After 10 years the incidence of metachronous contralateral breast cancer was 6.4 per cent for familial non-BRCA1/2 tumours versus 5.4 per cent for sporadic cancers. The rate of ipsilateral recurrence was not significantly increased (17.0 versus 14.2 per cent, respectively, at 10 years; P = 0.132). Tumour size (hazard ratio (HR) 1.02 per mm increase, P = 0.016) and node status (HR 2.6 for three or more involved nodes versus node negative, P = 0.017) were independent predictors of overall survival in the familial non-BRCA1/2 group, and in the whole group, whereas contralateral breast cancer (HR 0.7, P = 0.503) and risk-reducing contralateral mastectomy (HR 0.4, P = 0.163) were not.

CONCLUSION

Stage at detection was a key determinant of prognosis in familial non-BRCA1/2 breast cancer, whereas contralateral cancer was not. Risk-reducing contralateral mastectomy did not significantly improve survival, but early detection can. Decisions on breast-conserving treatment can be made on the same grounds in patients with familial and sporadic breast cancer.

Familial and inherited breast cancers in Lower Silesia (Poland)

The purpose of this study was to determine the frequencies of hereditary and familial breast cancers among Lower Silesian women. The questionnaires, dealing with cancer episodes in first-and second-degree relatives, were sent to 5,000 females, who were diagnosed with breast cancer between 1984 and 2005. Twenty-five percent of the questionnaires were completed and returned. Their analysis and further counseling revealed that 24.9% of the responders met the criteria for familial breast cancer (FBC), including 10.5% definitive cases. Mutations in BRCA1 were detected in 32.5% and 1.9% of patients with definitive and suspected FBC, respectively. They all represented three of the abnormalities of the BRCA1 gene: 300T/G, 4153delA and 5382insC. No mutations of BRCA2 were found in material studied. Although a fraction of FBCs identified in our study was similar to those described in other European countries and in the United States, the percentages of genetic mutations seen on routine tests were relatively low. Consequently, the standardized analysis of oncological pedigree seems to be a more valuable diagnostic tool if patients with familial aggregations of breast cancer are targeted in a prophylactic context only.

Prevalence and predictors of BRCA1 and BRCA2 mutations in a population-based study of breast cancer in white and black American women ages 35 to 64 years

Although well studied in families at high-risk, the roles of mutations in the BRCA1 and BRCA2 genes are poorly understood in breast cancers in the general population, particularly in Black women and in age groups outside of the very young. We examined the prevalence and predictors of BRCA1 and BRCA2 mutations in 1,628 women with breast cancer and 674 women without breast cancer who participated in a multicenter population-based case-control study of Black and White women, 35 to 64 years of age. Among cases, 2.4% and 2.3% carried deleterious mutations in BRCA1 and BRCA2, respectively. BRCA1 mutations were significantly more common in White (2.9%) versus Black (1.4%) cases and in Jewish (10.2%) versus non-Jewish (2.0%) cases; BRCA2 mutations were slightly more frequent in Black (2.6%) versus White (2.1%) cases. Numerous familial and demographic factors were significantly associated with BRCA1 and, to a lesser extent, BRCA2 carrier status, when examined individually. In models considering all predictors together, early onset ages in cases and in relatives, family history of ovarian cancer, and Jewish ancestry remained strongly and significantly predictive of BRCA1 carrier status, whereas BRCA2 predictors were fewer and more modest in magnitude. Both the combinations of predictors and effect sizes varied across racial/ethnic and age groups. These results provide first-time prevalence estimates for BRCA1/BRCA2 in breast cancer cases among understudied racial and age groups and show key predictors of mutation carrier status for both White and Black women and women of a wide age spectrum with breast cancer in the general population.

Optimal selection for BRCA1 and BRCA2 mutation testing using a combination of 'easy to apply' probability models

To establish an efficient, reliable and easy to apply risk assessment tool to select families with breast and/or ovarian cancer patients for BRCA mutation testing, using available probability models. In a retrospective study of 263 families with breast and/or ovarian cancer patients, the utility of the Frank (Myriad), Gilpin (family history assessment tool) and Evans (Manchester) model was analysed, to select 49 BRCA mutation-positive families. For various cutoff levels and combinations, the sensitivity and specificity were calculated and compared. The best combinations were subsequently validated in additional sets of families. Comparable sensitivity and specificity were obtained with the Gilpin and Evans models. They appeared to be complementary to the Frank model. To obtain an optimal sensitivity, five ‘additional criteria’ were introduced that are specific for the selection of small or uninformative families. The optimal selection is made by the combination ‘Frank ⩾16% or Evans2 ⩾12 or one of five additional criteria’. The efficiency of the selection of families for mutation testing of BRCA1 and BRCA2 can be optimised by using a combination of available easy to apply risk assessment models.

A DGGE system for comprehensive mutation screening of BRCA1 and BRCA2: application in a Dutch cancer clinic setting

Rapid and reliable identification of deleterious changes in the breast cancer genes BRCA1 and BRCA2 has become one of the major issues in most DNA services laboratories. To rapidly detect all possible changes within the coding and splice site determining sequences of the breast cancer genes, we established a semiautomated denaturing gradient gel electrophoresis (DGGE) mutation scanning system. All exons of both genes are covered by the DGGE scan, comprising 120 amplicons. We use a semiautomated approach, amplifying all individual amplicons with the same PCR program, after which the amplicons are pooled. DGGE is performed using three slightly different gel conditions. Validation was performed using DNA samples with known sequence variants in 107 of the 120 amplicons; all variants were detected. This DGGE mutation scanning, in combination with a PCR test for two Dutch founder deletions in BRCA1 was then applied in 431 families in which 52 deleterious changes and 70 unclassified variants were found. Fifteen unclassified variants were not reported before. The system was easily adopted by five other laboratories, where in another 3,593 families both exons 11 were analyzed by the protein truncation test (PTT) and the remaining exons by DGGE. In total, a deleterious change (nonsense, frameshift, splice-site mutation, or large deletion) was found in 661 families (16.4%), 462 in BRCA1 (11.5%), 197 in BRCA2 (4.9%), and in two index cases a deleterious change in both BRCA1 and BRCA2 was identified. Eleven deleterious changes in BRCA1 and 36 in BRCA2 had not been reported before. In conclusion, this DGGE mutation screening method for BRCA1 and BRCA2 is proven to be highly sensitive and is easy to adopt, which makes screening of large numbers of patients feasible. The results of screening of BRCA1 and BRCA2 in more than 4,000 families present a valuable overview of mutations in the Dutch population.

Induction of the transferrin receptor gene by benzo[a]pyrene in breast cancer MCF-7 cells: potential as a biomarker of PAH exposure

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental DNA-damaging agents regarded as risk factors for human disease, including lung and breast cancer. The biotransformation of PAHs to carcinogenic metabolites is mediated by the aromatic hydrocarbon receptor (AhR), which activates transcription at xenobiotic responsive elements (XREs = 5'-GCGTG-3') found in the promoter regions of genes encoding for detoxifying enzymes, including CYP1A1 and CYP1B1. In this study, we wished to identify novel biomarkers that may be useful in monitoring critical carcinogenic events of the breast induced by PAHs. Using a GeneMAP CancerArray, we analyzed in breast cancer MCF-7 cells the temporal effects of the AhR agonist benzo[a]pyrene (B[a]P), which is a prototype PAH and known environmental carcinogen. Genes upregulated at least threefold by B[a]P and containing potential XREs within their promoter regions included CYP1A1, CYP1B1, paired box gene 3 (PAX3), cortactin (CTTN/EMS1), beta-2-microglobulin (B2M), and transferrin receptor (TfR). The stimulatory effects of B[a]P on expression of these genes were abrogated by cotreatment with the AhR antagonist flavonoid, alpha-napthoflavone (ANF). The TfR gene was selected for further analysis as its promoter region contains two potential XREs and its expression has been shown to be increased in breast cancer cells. Accumulation of TfR mRNA in B[a]P-treated cells was confirmed by quantitative real time PCR. Transient transfection studies indicated that the transcriptional activity of the TfR promoter was stimulated by B[a]P, whereas ANF counteracted this induction. These results indicate that the TfR gene may be a potential biomarker of PAH exposure.

gamma-Radiation-induced chromosomal mutagen sensitivity is associated with breast cancer risk in African-American women: caffeine modulates the outcome of mutagen sensitivity assay

Several different cancer studies have indicated that lymphocyte mutagen sensitivity is a marker of DNA repair deficiency and increased cancer risk. We have used a mutagen sensitivity assay (MSA) measuring gamma-radiation-induced chromosomal aberrations in freshly cultured lymphocytes and assessed breast cancer risk in African-American women. Concurrently, we conducted duplicate cultures in the presence of caffeine, which overrides G(2) arrest in cultured cells, decreases time to DNA repair, and hence increases the aberration rate. In comparison with the non-caffeine-treated cells, we are conceptually segregating the contribution of DNA repair and time for DNA repair as individual susceptibility phenotypes. Blood samples were obtained from 61 cases and 86 controls at Howard University Hospital. Two sets of whole-blood cultures were established and gamma-irradiated (1 Gy) at 67 hours, one of which was treated with caffeine (1 mg/mL). Thereafter, cultures were processed for obtaining metaphase spreads. Fifty metaphases were screened for chromatid breaks. The mean breaks per cell (MBPC) for cases (0.34 +/- 0.15) was significantly greater than for controls (0.24 +/- 0.12; P < 0.0001). Using the 75th percentile value of controls as a cutoff to define mutagen sensitivity, the sensitive individuals had an odds ratio of 4.5 (95% confidence intervals, 2.2-9.1) for breast cancer compared with individuals that were not sensitive. The adjusted odds ratio was 3.3 (95% confidence intervals, 0.147-73.917), which was statistically significant but was limited by the small number of subjects. The results for caffeine co-culture were not predictive of breast cancer (MBPC: cases, 1.6 +/- 0.9 versus controls, 1.5 +/- 0.8; P = 0.8663). Comparing the MBPC for caffeine and non-caffeine cultures, there was a correlation in controls (n = 79; Spearman r = 0.4286; P < 0.0001), but not in cases (n = 58; Spearman r = 0.06609; P = 0.6221). This study indicates that the MSA phenotype is a risk factor for breast cancer in African-American women, with a significant effect observable even in small studies. The use of caffeine did not enhance the predictivity of MSA, but the correlation with non-caffeine cultures in controls indicates that the MSA phenotype is due to both DNA repair and G(2) arrest capacity.

Family history, and impact on clinical presentation and prognosis, in a population-based breast cancer cohort from the Stockholm County

BACKGROUND

The aim of the present study was to define the proportion of different levels of family history in a cohort of consecutive breast cancer patients from the Stockholm region, and to assess whether familial breast cancer has phenotypic traits different from those of sporadic patients.

METHODS

All incident breast cancer patients in a 19-month period were eligible for the study and 70% (489/696) participated. The family history and clinical parameters were obtained from questionnaires and medical records.

RESULTS

In total 35% had a family history. Age at onset was 58.9 years in the familial group vs. 60.7 years in the sporadic patients (P = 0.14) and 8% of the familial patients had bilateral breast cancer compared to 4% in the sporadic group (P = 0.08). There were 31% node positive tumors in the sporadic group vs. 22% in the cases with family history (P = 0.04). Hormonal background, treatment and prognosis (median follow-up 4.7 years) were not related to family history.

CONCLUSION

In addition to high-risk familial breast and breast-ovarian cancer, constituting about 10% of all breast cancer cases, another 25% of the breast cancer cases have a family history, a group hypothetically valuable for association studies on low-risk genes. In contrast to previous reports, we did not observe a relationship between family history and phenotypic traits. A possible explanation for this can be different study design. The considerable heterogeneity in familial breast cancer means that different criteria for familiality can influence the result. Furthermore, our study was prospective and population based and included paternal inheritance.

A genome wide linkage search for breast cancer susceptibility genes

Mutations in known breast cancer susceptibility genes account for a minority of the familial aggregation of the disease. To search for further breast cancer susceptibility genes, we performed a combined analysis of four genome-wide linkage screens, which included a total of 149 multiple case breast cancer families. All families included at least three cases of breast cancer diagnosed below age 60 years, at least one of whom had been tested and found not to carry a BRCA1 or BRCA2 mutation. Evidence for linkage was assessed using parametric linkage analysis, assuming both a dominant and a recessive mode of inheritance, and using nonparametric methods. The highest LOD score obtained in any analysis of the combined data was 1.80 under the dominant model, in a region on chromosome 4 close to marker D4S392. Three further LOD scores over 1 were identified in the parametric analyses and two in the nonparametric analyses. A maximum LOD score of 2.40 was found on chromosome arm 2p in families with four or more cases of breast cancer diagnosed below age 50 years. The number of linkage peaks did not differ from the number expected by chance. These results suggest regions that may harbor novel breast cancer susceptibility genes. They also indicate that no single gene is likely to account for a large fraction of the familial aggregation of breast cancer that is not due to mutations in BRCA1 or BRCA2.

Screening in women's health, with emphasis on fetal Down's syndrome, breast cancer and osteoporosis

Screening tests have become increasingly popular in women's health care over the last two decades. The initiative for screening is typically generated by either an agency or the health care professional being consulted for some reason. In many instances, however, the demand for screening tests is patient driven with the health care provider being poorly prepared to determine the usefulness of screening. This review illustrates the complexity of screening using three disorders where early detection and treatment have the potential to improve the quality and longevity of life. Prenatal diagnosis of Down's syndrome does not offer the parents the opportunity for cure but does offer the opportunity for education and rational choice as the impact of the diagnosis on the family is weighed. The evidence for breast cancer screening is more persuasive for older than younger women, but even in older women, there is a balance of risks and benefits. Treatment options for osteoporosis have improved in terms of reductions in fracture risk as well as beneficial effects on bone density, but evidence of the effectiveness of a screening programme for this condition in an unselected population is lacking. Ultimately, it is crucial that women be provided with clear and comprehensive information about the screening programme, in terms of possible gains but also costs of various kinds: physical, economic and psychological.

Aurora kinases A and B and familial breast cancer risk

Aurora genes play a crucial role in tumourigenesis and are overexpressed in many kinds of cancers. We investigated whether coding variants within the Aurora genes are associated with familial breast cancer risk. While AURKA Phe31Ile (1712T>A) and AURKB Thr298Met (893G>A) showed no association, the synonymous AURKB Ser295Ser (885A>G) polymorphism resulted in an increased breast cancer risk for carriers of the homozygous 885G genotype (OR=1.45, 95% CI=1.05-2.0, P=0.02). Due to the impact of aurora kinases in the loss of chromosomal integrity during carcinogenesis, this variant may also influence the therapy outcome in breast cancer.

Radiotherapy and genetic predisposition to breast cancer

Cancer genetics is becoming increasingly integrated into oncological care; particularly in breast cancer management. The recognition of monogenic breast cancer predisposition syndromes, such as BRCA, is critical as there is also a risk of other cancers in addition to a markedly elevated risk of contralateral breast cancer. In individuals with breast cancer due to some predisposition genes, radiation should be avoided, e.g. the ATM and TP53 genes, but there is still controversy as to whether radiation should be used in BRCA1/2 mutation carriers and more follow-up is needed. There are some radiation-sensitive genetic conditions where, if breast cancer occurs (as it may occur in any individual, not necessarily due to an increased risk associated with the condition), radiation should be avoided. These conditions are often associated with dysmorphic features. If such features are noticed then the advice of a geneticist should be sought urgently prior to giving radiation.

Evaluation of RAD50 in familial breast cancer predisposition

The genes predisposing to familial breast cancer are largely unknown, but 5 of the 6 known genes are involved in DNA damage repair. RAD50 is part of a highly conserved complex important in recognising, signalling and repairing DNA double-strand breaks. Recently, a truncating mutation in the RAD50 gene, 687delT, was identified in 2 Finnish breast cancer families. To evaluate the contribution of RAD50 to familial breast cancer, we screened the whole coding region for mutations in 435 UK and 46 Finnish familial breast cancer cases. We identified one truncating mutation, Q350X, in one UK family. We screened a further 544 Finnish familial breast cancer cases and 560 controls for the 687delT mutation, which was present in 3 cases (0.5%) and 1 control (0.2%). Neither Q350X nor 687delT segregated with cancer in the families in which they were identified. Functional analyses suggested that RAD50 687delT is a null allele as there was no detectable expression of the mutant protein. However, the wild-type allele was retained and expressed in breast tumors from mutation carriers. The abundance of the full-length RAD50 protein was reduced in carrier lymphoblastoid cells, suggesting a possible haploinsufficiency mechanism. These data indicate that RAD50 mutations are rare in familial breast cancer and either carry no, or a very small, increased risk of cancer. Altogether, these results suggest RAD50 can only be making a very minor contribution to familial breast cancer predisposition in UK and Finland.

[Identification and management of hereditary breast-ovarian cancers (2004 update)]

BACKGROUND

Since the last recommendations, up to 2500 new references had been published on that topic.

METHODOLOGY

On the behalf of the health Minister, the Ad Hoc Committee consisted of 13 experts carried out a first version revisited by five additional experts who critically analyzed the first version of the report.

MAIN UPDATING

Breast and ovarian cancer seem to be associated with fewer deleterious mutations of BRCA1 and BRCA2 than previously thought. The screening of ovarian cancer is still not an attractive option while in contrast MRI may be soon for these young women with dense breast, the recommended option for breast cancer screening. The effectiveness of prophylactic surgeries is now well established. French position is to favor such surgeries with regard to a quality of life in line with the expected benefit, and providing precise and standardized process described in the recommendation.

CONCLUSIONS

Due to methodological flaws, the low power and a short follow-up of the surveys, this statement cannot however aspire to a high stability.

BRCA1, BRCA2 and TP53 mutations in very early-onset breast cancer with associated risks to relatives

Pathological mutations in BRCA1, BRCA2 and TP53 are associated with an increased risk of breast cancer. This study evaluated mutation frequency of these genes in early-onset breast cancer patients, and correlated this with family history and determined relative risks to family members. Patients with breast adenocarcinoma diagnosed 30 years were ascertained between 1980 and 1997. Family history was established and mutation screening of BRCA1, BRCA2 and TP53 genes was performed. Estimates of penetrance and relative risk were undertaken. DNA was obtained from 100/139 women. 17/36 familial cases had a BRCA1, BRCA2 or TP53 mutation. Of 64 non-familial cases, one BRCA2, two BRCA1 and two TP53 mutations were detected. Penetrance estimates (by age 70) for breast cancer were 84% for BRCA1 mutations and 91% for BRCA2 mutations and for ovarian cancer, 60% and 26%, respectively. Relative risks associated with mutations were consistent with previous studies. BRCA1 and BRCA2 mutations in patients with breast cancer 30 years are predicted strongly by family history. The majority of families with ovarian cancer were due to mutations in BRCA1/2 whereas these mutations only accounted for 30-50% of the excess breast cancers.

Screen-positive rates and agreement among six family history screening protocols for breast/ovarian cancer in a population-based cohort of 21- to 55-year-old women

PURPOSE

Mutations in the BRCA1 and BRCA2 genes are responsible for approximately 2% of breast cancers by age 70 years. Professional and governmental groups recommend using family history protocols as an initial step in identifying women and families for mutation testing. We assess screen-positive rates and levels of agreement between these protocols.

METHODS

We applied six family history screening protocols to a population-based cohort of 321 women, age 21 to 55 years, who reported their personal and family history of breast and ovarian cancer.

RESULTS

The proportion of women and families identified as candidates for mutation testing ranged from 4.4% to 7.8%, depending on the protocol. The protocols had low or fair agreement (kappa <0.75 for 14 of 15 comparisons), but all identified six women (1.9%, 95% confidence interval 0.7%-4.0%) as screen positive. When the effect of missing ages of cancer onset was modeled, these rates increased (range 6.5%-11.5%), and nine women (2.8%) were screen positive by all protocols.

CONCLUSION

Given limitations of family history as a screening test for hereditary cancer related to BRCA1/2 mutations, 1% to 2% of women in the general population should initially be identified for mutation testing. One way to achieve this would be to require that multiple screening protocols agree.

Genetic and histopathologic evaluation of BRCA1 and BRCA2 DNA sequence variants of unknown clinical significance

Classification of rare missense variants as neutral or disease causing is a challenge and has important implications for genetic counseling. A multifactorial likelihood model for classification of unclassified variants in BRCA1 and BRCA2 has previously been developed, which uses data on co-occurrence of the unclassified variant with pathogenic mutations in the same gene, cosegregation of the unclassified variant with affected status, and Grantham analysis of the fit between the missense substitution and the evolutionary range of variation observed at its position in the protein. We have further developed this model to take into account relevant features of BRCA1- and BRCA2-associated tumors, such as the characteristic histopathology and immunochemical profiles associated with pathogenic mutations in BRCA1, and the fact that approximately 80% of tumors from BRCA1 and BRCA2 carriers undergo inactivation of the wild-type allele by loss of heterozygosity. We examined 10 BRCA1 and 15 BRCA2 unclassified variants identified in Australian, multiple-case breast cancer families. By a combination of genetic, in silico, and histopathologic analyses, we were able to classify one BRCA1 variant as pathogenic and six BRCA1 and seven BRCA2 variants as neutral. Five of these neutral variants were also found in at least 1 of 180 healthy controls, suggesting that screening a large number of appropriate controls might be a useful adjunct to other methods for evaluation of unclassified variants.

Increased level of chromosomal damage after irradiation of lymphocytes from BRCA1 mutation carriers

Deleterious mutations in the BRCA1 gene predispose women to an increased risk of breast and ovarian cancer. Many functional studies have suggested that BRCA1 has a role in DNA damage repair and failure in the DNA damage response pathway often leads to the accumulation of chromosomal aberrations. Here, we have compared normal lymphocytes with those heterozygous for a BRCA1 mutation. Short-term cultures were irradiated (8Gy) using a high dose rate and subsequently metaphases were analysed by 24-colour chromosome painting (M-FISH). We scored the chromosomal rearrangements in the metaphases from five BRCA1 mutation carriers and from five noncarrier control samples 6 days after irradiation. A significantly higher level of chromosomal damage was detected in the lymphocytes heterozygous for BRCA1 mutations compared with normal controls; the average number of aberrations per mitosis was 3.48 compared with 1.62 in controls (P=0.0001). This provides new evidence that heterozygous mutation carriers have a different response to DNA damage compared with noncarriers and that BRCA1 has a role in DNA damage surveillance. Our finding has implications for treatment and screening of BRCA1 mutation carriers using modalities that involve irradiation.

Genes de susceptibilidad al cáncer de mama

Five percent of all cases of breast cancer (BC) show a hereditary component related to gene mutations with an autosomic dominant transmission. To date, few genes are known to be responsible of hereditary BC. The germline mutations of BRCA1 or BRCA2 genes account for less than 50% of families with breast/ovarian cancer predisposition. The large percentage of families with multiple cases of female BC and no BRCA1 and BRCA2 mutations detected could be attributed to the existence of other high or low susceptibility genes acting together with lifestyle risk factors. The predisposition to BC in carriers of ATM mutations has been documented previously. Due to the frequency of ATM heterozygotes in the general population, the mutations in this gene could be associated with up to 5% of BC cases. The mutation 1100delC of the CHEK2 gene seems to be a low penetrance allele of BC susceptibility. The objective of the present manuscript is to review some of the susceptibility genes identified to date.

Age of uptake of early cancer detection facilities by low-risk and high-risk patients with familial breast and ovarian cancer

INTRODUCTION

Some 5-10% of all cases of breast cancer and ovarian cancer have a hereditary genesis. In the setting of an interdisciplinary cancer genetics clinic, a study of the age at which patients first take advantage of early cancer detection (ECD) facilities was conducted in order to assess the influence of familial risk on health issues.

METHODS

The study included 556 women who fulfilled the inclusion criteria (IC) for genetic analysis of the BRCA1 and BRCA2 genes, as well as 205 who did not meet these criteria but attended the primary consultation.

RESULTS

Consulters who met the inclusion criteria took advantage of nearly all methods of ECD at an earlier time than women who did not. A comparison of consulters with or without breast cancer showed that those without breast cancer participated in all methods of ECD at an earlier time.

CONCLUSION

Methods of improving and increasing participation in ECD facilities, and of encouraging women who are at risk to start on such programs at a younger age, need to be discussed. In this study, familial risk already resulted in a younger age of uptake of ECD facilities.

Lack of Germ-Line Promoter Methylation in BRCA1-Negative Families with Familial Breast Cancer

Hereditary breast cancer accounts for about 10% of breast cancer in the United States, but high-penetrance, germ-line mutations in BRCA1 and BRCA2 are responsible for less than half of these high-risk families. Epigenetic modification of DNA by promoter methylation can result in a potentially heritable epimutation that silences the gene. Using a highly sensitive technique, we assayed the BRCA1 gene for promoter methylation among 41 BRCA1- and BRCA2-negative women whose personal and family histories indicated a high risk of BRCA mutations (median prior likelihood = 60%) using the BRCAPro model. DNA from 19 women who were "true negatives" for BRCA mutations served as controls. We found no evidence for promoter methylation among the high-risk women who tested negative for germ-line BRCA mutations. Thus, epimutation is an unlikely explanation for hereditary breast cancer in women who test negative for BRCA mutations.

BRCA1 and BRCA2 mutation predictions using the BOADICEA and BRCAPRO models and penetrance estimation in high-risk French-Canadian families

Introduction

Several genetic risk models for breast and ovarian cancer have been developed, but their applicability to specific populations has not been evaluated. We used data from French-Canadian families to evaluate the mutation predictions given by the BRCAPRO and BOADICEA models. We also used this data set to estimate the age-specific risks for breast and ovarian cancer in BRCA1 and BRCA2 mutation carriers.

Methods

A total of 195 families with multiple affected individuals with breast or ovarian cancer were recruited through the INHERIT (INterdisciplinary HEalth Research International Team on BReast CAncer susceptibility) BRCAs research program. Observed BRCA1 and BRCA2 mutation status was compared with predicted carrier probabilities under the BOADICEA and BRCAPRO models. The models were assessed using Brier scores, attributes diagrams and receiver operating characteristic curves. Log relative risks for breast and ovarian cancer in mutation carriers versus population risks were estimated by maximum likelihood, using a modified segregation analysis implemented in the computer program MENDEL. Twenty-five families were eligible for inclusion in the BRCA1 penetrance analysis and 27 families were eligible for the BRCA2 penetrance analysis.

Results

The BOADICEA model predicted accurately the number of BRCA1 and BRCA2 mutations for the various groups of families, and was found to discriminate well at the individual level between carriers and noncarriers. BRCAPRO over-predicted the number of mutations in almost all groups of families, in particular the number of BRCA1 mutations. It significantly overestimated the carrier frequency for high predicted probabilities. However, it discriminated well between carriers and noncarriers. Receiver operating characteristic (ROC) curves indicate similar sensitivity and specificity for BRCAPRO and BOADICEA. The estimated risks for breast and ovarian cancer in BRCA1 and BRCA2 mutation carriers were consistent with previously published estimates.

Conclusion

The BOADICEA model predicts accurately the carrier probabilities in French-Canadian families and may be used for counselling in this population. None of the penetrance estimates was significantly different from previous estimates, suggesting that previous estimates may be appropriate for counselling in this population.

c-MYC Asn11Ser is associated with increased risk for familial breast cancer

c-MYC is a multifaceted protein that regulates cell proliferation, differentiation and apoptosis. Its crucial role in diverse cancers has been demonstrated in several studies. Here, we analysed the influence of the rare c-MYC Asn11Ser polymorphism on familial breast cancer risk by performing a case-control study with a Polish (cases n = 349; controls n = 441) and a German (cases n = 356; controls n = 655) study population. All cases have been tested negative for mutations in the BRCA1 and BRCA2 genes. A joint analysis of the Polish and the German study population revealed a 54% increased risk for breast cancer associated with the heterozygous Asn11Ser variant (OR = 1.54, 95% CI 1.05-2.26, p = 0.028). The breast cancer risk associated with this genotype increases above the age of 50 years (OR = 2.24, 95% CI 1.20-4.21, p = 0.012). The wild-type amino acid Asn of this polymorphism is located in the N-terminal MYC transactivation domain and is highly conserved not only among most diverse species but also in the N-MYC homologue. Due to the pivotal role of c-MYC in diverse tumours, this variant might affect the genetic susceptibility of other cancers as well.

Prediction of BRCA1 status in patients with breast cancer using estrogen receptor and basal phenotype

PURPOSE

To investigate the proportion of breast cancers arising in patients with germ line BRCA1 and BRCA2 mutations expressing basal markers and developing predictive tests for identification of high-risk patients.

EXPERIMENTAL DESIGN

Histopathologic material from 182 tumors in BRCA1 mutation carriers, 63 BRCA2 carriers, and 109 controls, collected as part of the international Breast Cancer Linkage Consortium were immunohistochemically stained for CK14, CK5/6, CK17, epidermal growth factor receptor (EGFR), and osteonectin.

RESULTS

All five basal markers were commoner in BRCA1 tumors than in control tumors (CK14: 61% versus 12%; CK5/6: 58% versus 7%; CK17: 53% versus 10%; osteonectin: 43% versus 19%; EGFR: 67% versus 21%; P < 0.0001 in each case). In a multivariate analysis, CK14, CK5/6, and estrogen receptor (ER) remained significant predictors of BRCA1 carrier status. In contrast, the frequency of basal markers in BRCA2 tumors did not differ significant from controls.

CONCLUSION

The use of cytokeratin staining in combination with ER and morphology provides a more accurate predictor of BRCA1 mutation status than previously available, that may be useful in selecting patients for BRCA1 mutation testing. The high percentage of BRCA1 cases positive for EGFR suggests that specific anti-tyrosine kinase therapy may be of potential benefit in these patients.

BAP1 and Breast Cancer Risk

BAP1 whose protein interacts with BRCA1 was analysed in a series of 47 French familial breast cancer cases negatively tested for BRCA1/2 mutations. The lack of detection of deleterious mutations suggests that BAP1 is not a high risk breast cancer predisposing gene. However, a common identified variant, rs123602, may be tested in sporadic cases as candidate for moderate risk.

Interaction between CHEK2*1100delC and other low-penetrance breast-cancer susceptibility genes: a familial study

BACKGROUND

The allele CHEK2*1100delC doubles the risk of breast cancer in unselected women, but could confer a greater risk in women with a family history of the disease, particularly of bilateral breast cancer. Our aim was to measure the risk of breast cancer in relatives of women with bilateral breast cancer who were carriers of this allele.

METHODS

A population-based series of 469 bilateral breast cancer cases ascertained through English cancer registries were genotyped for CHEK2*1100delC. Standardised incidence ratios (SIRs) and cumulative risks were calculated for breast cancer, prostate cancer, and all other cancers in the first-degree relatives of carriers and non-carriers.

FINDINGS

The relatives of bilateral cases who were wild-type for CHEK2 had three times the population risk of female breast cancer (145 cases: SIR 3.48 (95% CI 2.96-4.09), twice the risk of prostate cancer (34 cases: SIR 2.41, 1.67-3.36) and a large excess of male breast cancer (five cases: SIR 15.06, 4.92-35.36). Relatives of those who were carriers of CHEK2*1100delC had a substantially higher risk of breast cancer (eight cases: SIR 12.11, 5.23-23.88) and possibly prostate cancer (two cases: SIR 9.87, 1.20-35.67).

INTERPRETATION

These data suggest a multiplicative interaction between CHEK2*1100delC and other unknown susceptibility genes. In women with a family history of bilateral disease, CHEK2*1100delC confers a high lifetime risk and might be useful for predictive testing. Bilateral breast cancer cases and their families are likely to provide an efficient basis for identification of additional low-penetrance breast-cancer genes.

Spectrum and prevalence of BRCA1 and BRCA2 germline mutations in Sardinian patients with breast carcinoma through hospital-based screening

BACKGROUND

Factors that are predictive of carrying BRCA1 and BRCA2 germline mutations in patients with breast carcinoma are awaited widely. The genetically homogeneous Sardinian population may be useful for defining the role of such genetic alterations further through a clinical evaluation program.

METHODS

One hundred two of 659 patients with breast carcinoma (15.5%) who were collected consecutively had a family history of breast carcinoma and were screened for BRCA1/2 mutations by denaturing high-performance liquid chromatography and DNA sequencing.

RESULTS

Three deleterious germline BRCA1/2 mutations were detected in 15 of 102 families (14.7%), including 13 families (86.7%) with BRCA2 mutations and 2 families (13.3%) with BRCA1 mutations. A single variant, BRCA2-8765delAG, was the most recurrent mutation in the series and was found in 12 of 102 families (11.8%) and in 18 of 657 patients (2.7%). The average age at diagnosis was significantly younger in families with BRCA1/2 mutations (48.6 yrs) compared with the age of patients who had no detectable mutation (52.9 yrs; P = 0.039). Moreover, BRCA1/2 mutations were found at a significantly higher rate in families who had at least 1 member with ovarian carcinoma or male breast carcinoma (5 of 12 families; 41.7%) than in families without such an association (10 of 90 families; 11.1%; P = 0.003).

CONCLUSIONS

BRCA2 mutations were approximately 6 times more prevalent than BRCA1 mutations. A diagnosis of breast carcinoma before age 50 years, ovarian carcinoma, male breast carcinoma, and 3 affected generations all were associated significantly with BRCA1/2 mutations. Although the current findings provided further support for the hypothesis that additional breast carcinoma susceptibility genes remain to be identified, such indicators of the presence of BRCA1/2 mutations may be useful in counseling patients about undergoing genetic testing.

Mammographic breast density as an intermediate phenotype for breast cancer

The amount of radiologically dense breast-tissue appearing on a mammogram varies between women because of differences in the composition of breast tissue, and is referred to here as mammographic density. This review presents evidence that mammographic density is a strong risk factor for breast cancer, and that risk of breast cancer is four to five times greater in women with density in more than 75% of the breast than in women with little or no density in the breast. Density in more than 50% of the breast could account for about a third of breast cancers. The epidemiology of mammographic density is consistent with its being a marker of susceptibility to breast cancer. Twin studies have shown that the proportion of the breast occupied by density, at a given age, is highly heritable, and inherited factors explain 63% of the variance. Mammographic breast density has the characteristics of a quantitative trait and might be determined by genes that are easier to identify than those for breast cancer itself. The genes that determine breast density might also be associated with risk of breast cancer, and their identification is also likely to provide insights into the biology of the breast and identify potential targets for preventive strategies.

The joint effect of smoking and AIB1 on breast cancer risk in BRCA1 mutation carriers

Women with BRCA1 mutations are at an elevated risk for breast cancer. AIB1 (NCOA3/SRC3) genotype and smoking may alter this risk. We examined the differences in breast cancer risk by AIB1 polyglutamine repeat polymorphism and pre-diagnosis smoking habits for BRCA1 mutation carriers to determine if there was an interaction between smoking and AIB1 genotype. Multivariate Cox proportional hazards regression was used with 316 female BRCA1 mutation carriers to model breast cancer risk. Ever having smoked was associated with a decreased breast cancer risk [Hazard Ratio (HR) = 0.63, 95% CI, 0.47-0.87]. A dose-response relationship between number of pack-years smoked and breast cancer risk was also found for women who smoked <20 pack years of cigarettes (HR = 0.72, 95% CI, 0.52-1.00) and for women who smoked >/=20 pack years (HR = 0.41, 95% CI, 0.23-0.71; P for trend = 0.0007). Women with a 28 repeat allele for AIB1 had a significantly reduced risk of breast cancer (HR = 0.72, 95% CI, 0.51-1.00). Women who smoked >/=20 pack-years with a 28 repeat allele had an even greater reduced risk of breast cancer (HR = 0.19, 95% CI, 0.07-0.54) compared to women who were never smokers with no 28 allele. Since AIB1 appears to modulate the effect of endogenous hormones via the estrogen receptor, and smoking affects circulating hormone levels, these results support evidence that steroid hormones play an important role in breast carcinogenesis in BRCA1 mutation carriers, and suggest mechanisms for developing novel cancer prevention strategies for BRCA1 mutation carriers.

Population-based family studies in genetic epidemiology

Designs that involve families (the traditional strength of genetic epidemiology) and population-based sampling (the traditional strength of environmental epidemiology) allow investigation of both genes and environment, separately or together, and allow valid inference to the population. These case-control-family designs (including those involving twin pairs), can be regarded as retrospective cohort studies of relatives, and can be used for: determining familial risks and genetic models; estimating risk (penetrance) for measured genotypes; genetic association studies; stratifying risks by family history and known mutation status; and studying modifiers of risk in genetically susceptible individuals. Follow-up of families allows genetic and environmental risks to be studied prospectively. We discuss statistical methods, theoretical and practical strengths, limitations, and other issues. Given their versatility, population-based family studies could become a principal framework in epidemiology, and move genetics from its traditional focus on high-risk families to give it a wider clinical and population health relevance.

Adjusting the estimated proportion of breast cancer cases associated with BRCA1 and BRCA2 mutations: public health implications

PURPOSE

Mutations in BRCA1 or BRCA2 genes increase breast cancer risk. Assuring reliability of information about these mutations is increasingly important to the health care community; mutation testing is becoming more widespread. We describe a methodology for assessing such information.

METHODS

Our approach integrates four interdependent epidemiologic parameters: (1) the probability of developing breast cancer, (2) the proportion of breast cancer cases with a BRCA1 or BRCA2 mutation, (3) the proportion of women that carries a mutation, and (4) the proportion of women with a mutation that develops cancer. We assess the plausibility of estimates of these parameters from published reports and commonly accessed information sources.

RESULTS

Assuming a fixed probability of developing breast cancer, the following estimates for the other three epidemiologic parameters are derived for women by age 70: 1% to 2% of all breast cancer cases are associated with a BRCA1 or BRCA2 mutation; 1 in 300 to 1 in 465 women carry a mutation; and 35 to 65% of mutation carriers develop breast cancer. Within these ranges, however, only selected combinations are plausible. The proportion of mutation-related breast cancer is lower than listed in some common information sources (1 to 2% vs 6%). Also, penetrance is somewhat lower and the carrier rate somewhat higher.

CONCLUSIONS

The four epidemiologic parameters can be integrated to test their plausibility. BRCA1 and BRCA2 mutations are associated with only one-third as many breast cancer cases in the general population as reported by commonly accessed information sources.

An evaluation of BRCA1 and BRCA2 founder mutations penetrance estimates for breast cancer among Ashkenazi Jewish women

PURPOSE

Three founder mutations in BRCA1 or BRCA2 genes increase breast cancer risk among Ashkenazi Jewish women. Reported estimates of the magnitude of this risk vary widely. We describe an integrated approach for assessing the plausibility of these estimates.

METHODS

Our approach integrates four epidemiologic parameters: (1) the proportion of all breast cancer cases with a founder mutation, (2) the proportion of women that carry one of these mutations, (3) the proportion of women with a mutation that develops cancer, and (4) the number of women who will develop cancer, regardless of mutation status. We then assess the published estimates of the proportion of Ashkenazi Jewish women with a mutation that develops cancer in the context of the other three parameters.

RESULTS

Penetrance for the founder mutations by ages 40, 50, and 70 are approximately 7%, 20%, and 40%, respectively. In two of the four published studies that evaluated at least two of the four parameters, penetrance estimates were internally consistent with the other three parameters and were also consistent with our consensus estimate. The third study had incomplete data. In the fourth study, the penetrance estimate was not internally consistent with the other three parameters, nor was it consistent with the consensus estimate.

CONCLUSIONS

The four epidemiologic parameters are interdependent and can be used to test the plausibility of any one parameter. Based on the range of breast cancer penetrance estimates for BRCA1 and BRCA2 founder mutations derived by our approach, recently reported penetrance estimates appear to be overestimated.

Contribution of BRCA1 and BRCA2 germ-line mutations to the incidence of breast cancer in young women: results from a prospective population-based study in France

The prevalence of BRCA1/2 germ-line mutations was assessed in a prospective population-based series of early-onset breast cancer (BC) patients in France, and the usefulness of a clinical assessment of hereditary BC risk, based on multiple criteria including pedigree structure, was evaluated. Through the Rhone region BC registry, 232 women diagnosed with BC before 46 years of age were included. They were tested for BRCA1/2 mutations an average of 10 months after diagnosis. All the women were classified according to their family history of cancer: high risk of hereditary breast cancer (HBC), low risk of HBC, isolated BC, and unknown HBC risk. Deleterious mutations were observed in 21 women (9.1%): 15 (6.5%) BRCA1 and 6 (2.6%) BRCA2. Mutations were more prevalent in women who developed BC before age 41 than in women who developed BC between ages 41 and 45 (12.8% versus 5.2%, respectively, P = 0.04). A high prevalence of BRCA1/2 mutations was found among women in the high-risk category with particular family features (i.e., small family size, predominantly male pedigree, specific cancers; 23.5%) and among women with isolated BC before age 41 and with five or fewer close adult female relatives (16.6%). According to the 10% probability level recommended by the American Society of Clinical Oncology guidelines for genetic testing of cancer, BRCA1/2 mutation screening should be considered for all women diagnosed before age 41, except for those with isolated BC in a large pedigree including multiple unaffected female relatives. The clinical assessment of HBC risk that we have developed should help in the decision to perform genetic testing.

Breast cancer risk following radiotherapy for Hodgkin lymphoma: modification by other risk factors

The importance of genetic and other risk factors in the development of breast cancer after radiotherapy (RT) for Hodgkin lymphoma (HL) has not been determined. We analyzed data from a breast cancer case-control study (105 patients, 266 control subjects) conducted among 3 817 survivors of HL diagnosed at age 30 years or younger in 6 population-based cancer registries. Odds ratios (ORs) and excess relative risks (ERRs) were calculated using conditional regression. Women who received RT exposure (> or = 5 Gy radiation dose to the breast) had a 2.7-fold increased breast cancer risk (95% confidence interval (CI) 1.4-5.2), compared with those given less than 5 Gy. RT exposure (> or = 5 Gy) was associated with an OR of 0.8 (95% CI, 0.2-3.4) among women with a first- or second-degree family history of breast or ovarian cancer, and 5.8 (95% CI, 2.1-16.3) among all other women (interaction P = .03). History of a live birth appeared to increase the breast cancer risk associated with RT among women not treated with ovarian-damaging therapies. Breast cancer risk following RT varied little according to other factors. The additional increased relative risk of breast cancer after RT for HL is unlikely to be larger among women with a family history of breast or ovarian cancer than among other women.

Common variation in EMSY and risk of breast and ovarian cancer: a case-control study using HapMap tagging SNPs

BACKGROUND

EMSY could be involved in low-level susceptibility to breast and ovarian cancer. Gene amplification is seen in a proportion of breast and ovarian tumours and correlates with poor prognosis in breast cancer patients. Furthermore, the EMSY protein silences a transcription activation domain in BRCA2 exon 3.

METHODS

We used a genetic association study design to determine if common genetic variation (frequency > or = 5%) in EMSY was associated with breast or ovarian cancer risk in the British population. Haplotype tagging single-nucleotide polymorphisms (htSNPs) were selected from the HapMap database and genotyped using Taqman in two large study sets of white British women (n [breast set] = 2343 cases and 2284 controls, n [ovarian set] = 864 cases and 864 controls). HapMap data might be insufficient to tag genetic variation in EMSY comprehensively. We therefore screened the gene promoter and coding sequences with denaturing high performance liquid chromatography in order to identify additional SNPs that are most likely to be functional.

RESULTS

HapMap data on 22 SNPs show that 4 htSNPs tag 4 common haplotypes: rs2282611 (5'up t > g), rs4245443 (IVS7 g > a), rs2513511 (IVS16 a > g), rs2155220 (3'down c > t). We observed no association between any of the genotypes or associated haplotypes and breast or ovarian cancer risk. Seventeen out of the 18 remaining HapMap polymorphisms (94%) were well tagged by the 4 selected htSNPs (r2s > 0.8). Genotype frequencies for two further SNPs identified by screening and located near exon-intron boundaries, rs2508740 (IVS9 a > g) and rs11600501 (IVS10 c > t), were also similar in cases and controls. In order to simulate unidentified SNPs, we performed the leave-one-out cross-validation procedure on the HapMap data; over 95% of the common genetic variation was well represented by tagging polymorphisms. We are therefore likely to have tagged any common, functional variants present in our population.

CONCLUSION

We found no association between common genetic variation in EMSY and risk of breast or ovarian cancer in two large study sets of white British women.

Polymorphisms in the IGF-1 and IGFBP3 promoter and the risk of breast cancer

Binding of IGF-1 to the type I IGF receptor starts a signalling cascade that plays an important role in regulating cell proliferation, differentiation and apoptosis. The interaction between the IGF-1 and its receptor is mainly regulated by a binding protein, IGFBP 3. We studied a CA repeat polymorphism 969 bp upstream of the transcription start site in the IGF-1 gene and an A-202 C polymorphism in the IGFBP 3 gene and tested their association with breast cancer risk using four case-control series with a total of 787 cases and 900 controls. We did not find any association between the breast cancer risk and the IGF-1 repeat length (19 versus non-19) or the IGFBP 3 A-202 C polymorphism in the postmenopausal breast cancer series or in women diagnosed for breast cancer under the age of 50. In the familial breast cancer series we observed a non-significantly increased odds-ratio (OR) in homozygotes for the non-19 alleles of the IGF-1 gene (OR 1.51, 95% CI 0.96-2.39, p=0.07). Similarly, in the familial breast cancer series we detected an increased frequency of the IGFBP 3 -202 C allele carriers (OR 1.50, 95% CI 1.05--2.14, p=0.03). The association was stronger in individuals homozygous for these alleles (OR 3.76, 95% CI 1.44-v-9.81, p=0.006). Thus, the polymorphisms in the IGF-1 and IGFBP 3 genes associated with an increased risk of breast cancer in familial cases carrying the variant alleles.

A prospective study on predictive factors linked to the presence of BRCA1 and BRCA2 mutations in breast cancer patients

We prospectively screened a hospital-based population of 1000 successive breast cancer patients receiving adjuvant radiotherapy for predictive factors associated with the presence of BRCA1 and BRCA2 mutations. We offered genetic counseling and DNA analysis to selected patients. About 52% of patients showed at least one presumed predictive factor. Hundred and thirty-seven patients underwent DNA analysis. We identified 14 deleterious mutations (10.2%, 95% CI: 5.2-15.3%): 8 BRCA1 mutations and 6 BRCA2 mutations and 14 variants of uncertain clinical significance. Ovarian cancer in the family history was the only factor significantly associated with the presence of a disease-causing mutation (P < 0.01). Eight of the 14 (57%) mutation carriers had no affected first-degree relatives and in 4 of these there was no family history of breast or ovarian cancer. Clinicians should offer genetic counseling and DNA testing to breast cancer patients from families with breast and ovarian cancer, and to patients who are younger than 45 years when they are diagnosed with breast cancer.

Cancer risk prediction models: a workshop on development, evaluation, and application

Cancer researchers, clinicians, and the public are increasingly interested in statistical models designed to predict the occurrence of cancer. As the number and sophistication of cancer risk prediction models have grown, so too has interest in ensuring that they are appropriately applied, correctly developed, and rigorously evaluated. On May 20-21, 2004, the National Cancer Institute sponsored a workshop in which experts identified strengths and limitations of cancer and genetic susceptibility prediction models that were currently in use and under development and explored methodologic issues related to their development, evaluation, and validation. Participants also identified research priorities and resources in the areas of 1) revising existing breast cancer risk assessment models and developing new models, 2) encouraging the development of new risk models, 3) obtaining data to develop more accurate risk models, 4) supporting validation mechanisms and resources, 5) strengthening model development efforts and encouraging coordination, and 6) promoting effective cancer risk communication and decision-making.