Cancer incidence in relatives of a population-based set of cases of early-onset breast cancer with a known BRCA1 and BRCA2 mutation status

Cancer risks among first-degree relatives of women with a genetic predisposition to breast cancer

BACKGROUND

Associations between germline alterations in women and cancer risks among their relatives are largely unknown.

METHODS

We identified women from 2 Swedish cohorts Karolinska Mammography Project for Risk Prediction of Breast Cancer (KARMA) and prevalent KARMA (pKARMA), including 28 362 women with genotyping data and 13 226 with sequencing data. Using Swedish Multi-Generation Register, we linked these women to 133 389 first-degree relatives. Associations between protein-truncating variants in 8 risk genes and breast cancer polygenic risk score in index women and cancer risks among their relatives were modeled via Cox regression.

RESULTS

Female relatives of index women who were protein-truncating variant carriers in any of the 8 risk genes had an increased breast cancer risk compared with those of noncarriers (hazard ratio [HR] = 1.85, 95% confidence interval [CI] = 1.52 to 2.27), with the strongest association found for protein-truncating variants in BRCA1 and 2. These relatives had a statistically higher risk of early onset than late-onset breast cancer (P = .001). Elevated breast cancer risk was also observed in female relatives of index women with higher polygenic risk score (HR per SD = 1.28, 95% CI = 1.23 to 1.32). The estimated lifetime risk was 22.3% for female relatives of protein-truncating variant carriers and 14.4% for those related to women in the top polygenic risk score quartile. Moreover, relatives of index women with protein-truncating variant presence (HR = 1.30, 95% CI = 1.06 to 1.59) or higher polygenic risk score (HR per SD = 1.04, 95% CI = 1.01 to 1.07) were also at higher risk of nonbreast hereditary breast and ovary cancer syndrome-related cancers.

CONCLUSIONS

Protein-truncating variants of risk genes and higher polygenic risk score in index women are associated with an increased risk of breast and other hereditary breast and ovary syndrome-related cancers among relatives.

The association between prognosis of breast cancer and first-degree family history of breast or ovarian cancer: a systematic review and meta-analysis

Whether a positive family history of breast cancer or ovarian cancer (FHBOC) would affect the prognosis of breast cancer is still up for debate and further study. This meta-analysis was performed to clarify this issue. We reviewed two databases (PubMed and CNKI) for research articles published at any time from the inception of these databases to April 1, 2016 for articles detecting the impact of FHBOC on the prognosis of breast cancer. A meta-analysis was conducted to generated combined hazard ratios (HR) with 95% confidence intervals (CI) for overall survival (OS) and breast cancer-specific survival (BCSS). Eighteen studies were included in our qualitative analysis, with 15 studies ultimately part of the quantitative analysis. The pooled results demonstrated that a positive FHBOC was associated with better OS (0.89, 95% CI 0.83-0.95) and BCSS (0.90, 95% CI 0.82-0.99). In subgroup analyses, several subgroups (maximally adjusted studies, population based studies, high quality studies, family history of breast cancer, studies from Europe, studies from Asia, 1 affected relative, or tumor size > 2 cm), a positive first-degree FHBOC was associated with better prognosis of breast cancer. Notably, for those patients who underwent breast-conserving surgery, first-degree FHBOC was not a risk factor for OS (HR 1.08, 95% CI 0.53-2.21). Our meta-analysis demonstrated that a first-degree FHBOC was associated with better OS and BCSS in patients with breast cancer. These findings support that clinical management should not differ between women with and without FHBOC.

Founder and Recurrent Mutations in BRCA1 and BRCA2 Genes in Latin American Countries: State of the Art and Literature Review

BACKGROUND

Numerous epidemiological factors affect the probability of developing breast or ovarian cancer, but no predictor is as determinant as inheriting a mutation in BRCA1 or BRCA2. The concept of the founder effect explains the reduced genetic variability in some populations, according to the theory that new populations can be formed from a reduced number of individuals, so the new population would carry only a small fraction of the genetic variability of the original population. The main purpose of this review is to provide an update on the state of the art in founder mutations and some recurrent mutations that have recently been described in Latin America.

METHODS

A literature search was performed in the electronic databases of PUBMED, EMBASE, LILACS, and BIREME using the terms BRCA1, BRCA2, founder mutation, Latin American population, and Hispanic. Sixty-two papers were identified, of which 38 were considered relevant for this review. Each result is shown per country.

RESULTS

In Latin America, clear founder effects have been reported in Mexico (BRCA1 del exons 9-12), Brazil (BRCA1 5382insC and BRCA2 c.156_157insAlu), and Colombia (BRCA1 3450del4, A1708E, and BRCA2 3034del4) and in Latinas residing in Southern California (BRCA1 185delAG, IVS5+1G>A, S955x, and R1443x). Of these, mutation BRCA1 3450del4 has also been reported in Brazil and Chile, whereas mutation BRCA2 3034del4 has been reported in Argentina and Peru. These data support the idea that although most Hispanic populations are the result of a mixture between Europeans, Africans, and Amerindians, the relative proportion of each genetic component varies throughout the Hispanic populations, making it necessary to identify the mutations characteristic of each population to generate mutation profiles adjusted to each one of them.

CONCLUSION

In Latin American countries, and even among regions of the same country, there is great heterogeneity of ancestors. Therefore, Latinas should not be analyzed like other population groups without taking into account their genetic ancestry. The presence of founder mutations in specific population groups represents a cost-effective analysis. The importance of determining the founder mutations lies mainly in the decrease in costs. If we manage to decrease costs, screenings could be offered more widely and cover a larger number of women.

IMPLICATIONS FOR PRACTICE

Hispanic and African-American populations are four to five times less likely than other populations worldwide to receive screening for BRCA mutations, a main reason being the high costs of these tools. The present study seeks to identify the prevalent mutations and the founder effect in the BRCA gene in the Hispanic population to address specific panels for this population group in the future and develop strategies for population screening.

Estimate of the penetrance of BRCA mutation and the COS software for the assessment of BRCA mutation probability

We have designed the user-friendly COS software with the intent to improve estimation of the probability of a family carrying a deleterious BRCA gene mutation. The COS software is similar to the widely-used Bayesian-based BRCAPRO software, but it incorporates improved assumptions on cancer incidence in women with and without a deleterious mutation, takes into account relatives up to the fourth degree and allows researchers to consider an hypothetical third gene or a polygenic model of inheritance. Since breast cancer incidence and penetrance increase over generations, we estimated birth-cohort-specific incidence and penetrance curves. We estimated breast and ovarian cancer penetrance in 384 BRCA1 and 229 BRCA2 mutated families. We tested the COS performance in 436 Italian breast/ovarian cancer families including 79 with BRCA1 and 27 with BRCA2 mutations. The area under receiver operator curve (AUROC) was 84.4 %. The best probability threshold for offering the test was 22.9 %, with sensitivity 80.2 % and specificity 80.3 %. Notwithstanding very different assumptions, COS results were similar to BRCAPRO v6.0.

Skin cancer risk in BRCA1/2 mutation carriers

Women with BRCA1/2 mutations have an elevated risk of breast and ovarian cancer. These patients and their clinicians are often concerned about their risk for other cancers, including skin cancer. Research evaluating the association between BRCA1/2 mutations and skin cancer is limited and has produced inconsistent results. Herein, we review the current literature on the risk of melanoma and nonmelanoma skin cancers in BRCA1/2 mutation carriers. No studies have shown a statistically significant risk of melanoma in BRCA1 families. BRCA2 mutations have been linked to melanoma in large breast and ovarian cancer families, though a statistically significant elevated risk was reported in only one study. Five additional studies have shown some association between BRCA2 mutations and melanoma, while four studies did not find any association. With respect to nonmelanoma skin cancers, studies have produced conflicting results. Given the current state of medical knowledge, there is insufficient evidence to warrant increased skin cancer surveillance of patients with a confirmed BRCA1/2 mutation or a family history of a BRCA1/2 mutation, in the absence of standard risk factors. Nonetheless, suspected BRCA1/2 mutation carriers should be counselled about skin cancer risks and may benefit from yearly full skin examinations.

A randomized controlled trial of diet and physical activity in BRCA mutation carriers

High serum levels of insulin-like growth factor I (IGF-I) are associated with an increased risk of sporadic breast cancer (BC). Furthermore, insulin and markers of insulin resistance, such as abdominal obesity, high blood glucose, high serum testosterone and metabolic syndrome, may affect both BC incidence and prognosis. We hypothesized that all these factors might be relevant also for hereditary BC, due to a deleterious mutation of BRCA genes. Epidemiological observation suggested that weight, energy intake (usually associated with higher bio-availability of growth factors) and physical activity may be relevant in BRCA mutation carriers. Mechanistic studies hypothesized a functional interaction between BRCA genes and the IGF-I system. We have provided some evidence that high serum levels of IGF-I are associated with a significantly increased penetrance. We are recruiting a larger cohort of BRCA mutation carriers in order to test potential modulators of penetrance and prognosis. Within this cohort, we have planned a randomized controlled trial to test whether moderate calorie and protein restriction, together with physical activity, decrease IGF-I. Eligible study subjects are women with or without BC, aged 18-70, with a proven deleterious BRCA mutation, and without metastases. All the women will receive recommendations for the dietary prevention of cancer. The women will be then randomized into an active life-style intervention group and into a control group that will receive only the baseline recommendations. We expect to significantly reduce IGF-I in the intervention group. This trial and the subsequent cohort follow-up might open up primary prevention options for genetic BC.

Etiology of familial breast cancer with undetected BRCA1 and BRCA2 mutations: clinical implications

BACKGROUND

Familial breast cancer accounts for 20-30 % of all breast cancer cases. Mutations in the BRCA1 and BRCA2 genes account for the majority of high risk families with both early onset breast cancer and ovarian cancer. Most of the families with less than six breast cancer cases and no ovarian cancer do not carry BRCA1 or BRCA2 mutations that can be detected using routine sequencing protocols. Here, we aimed to review the etiology of familial breast cancer in cases without BRCA1 and BRCA2 mutations.

RESULTS

After excluding BRCA1 and BRCA2 mutations, factors proposed to contribute to familial breast cancer include: chance clustering of apparently sporadic cases, shared lifestyle, monogenic inheritance, i.e., dominant gene mutations associated with a high risk (TP53, PTEN, STK11), dominant gene mutations associated with a relatively low risk (ATM, BRIP1, RLB2), recessive gene mutations associated with horizontal inheritance patterns (sister-sister), and polygenic inheritance where susceptibility to familial breast cancer is thought to be conferred by a large number of low risk alleles.

CONCLUSIONS

Current evidence suggests that in the majority of cases with BRCA1 and BRCA2 negative familial breast cancer the etiology is due to interactions of intermediate or low risk alleles with environmental and lifestyle factors. Thus, a careful selection of patients submitted to genetic testing is needed. Clearly, further research is required to fully elucidate the etiology of non-BRCA familial breast cancer.

Tumour morphology of early-onset breast cancers predicts breast cancer risk for first-degree relatives: the Australian Breast Cancer Family Registry

Introduction

We hypothesised that breast cancer risk for relatives of women with early-onset breast cancer could be predicted by tumour morphological features.

Methods

We studied female first-degree relatives of a population-based sample of 452 index cases with a first primary invasive breast cancer diagnosed before the age of 40 years. For the index cases, a standardised tumour morphology review had been conducted for all; estrogen (ER) and progesterone receptor (PR) status was available for 401 (89%), and 77 (17%) had a high-risk mutation in a breast cancer susceptibility gene or methylation of the BRCA1 promoter region in peripheral blood DNA. We calculated standardised incidence ratios (SIR) by comparing the number of mothers and sisters with breast cancer with the number expected based on Australian incidence rates specific for age and year of birth.

Results

Using Cox proportional hazards modelling, absence of extensive sclerosis, extensive intraductal carcinoma, absence of acinar and glandular growth patterns, and the presence of trabecular and lobular growth patterns were independent predictors with between a 1.8- and 3.1-fold increased risk for relatives (all P <0.02). Excluding index cases with known genetic predisposition or BRCA1 promoter methylation, absence of extensive sclerosis, circumscribed growth, extensive intraductal carcinoma and lobular growth pattern were independent predictors with between a 2.0- and 3.3-fold increased risk for relatives (all P <0.02). Relatives of the 128 (34%) index cases with none of these four features were at population risk (SIR = 1.03, 95% CI = 0.57 to 1.85) while relatives of the 37 (10%) index cases with two or more features were at high risk (SIR = 5.18, 95% CI = 3.22 to 8.33).

Conclusions

This wide variation in risks for relatives based on tumour characteristics could be of clinical value, help discover new breast cancer susceptibility genes and be an advance on the current clinical practice of using ER and PR as pathology-based predictors of familial and possibly genetic risks.

Do Breast Cancer Patients Tested in the Oncology Care Setting Share BRCA Mutation Results with Family Members and Health Care Providers?

BRCA genetic test results provide important information to manage cancer risk for patients and their families. Little is known on the communication of genetic test results by mutation status with family members and physicians in the oncology care setting. As part of a longitudinal study evaluating the impact of genetic counseling and testing among recently diagnosed breast cancer patients, we collected patients' self-reported patterns of disclosure. Descriptive statistics characterized the sample and determined the prevalence of disclosure of BRCA test results to family members and physicians. Of 100 patients who completed the baseline and the 6-month followup survey, 77 reported pursuing testing. The majority shared test results with female first-degree relatives; fewer did with males. Participants were more likely to share results with oncologists compared to surgeons, primary care physicians, or other specialty physicians. These findings suggest that while breast cancer patients may communicate results to at-risk female family members and their medical oncologist, they may need education and support to facilitate communication to other first-degree relatives and providers.

Serum levels of IGF-I and BRCA penetrance: a case control study in breast cancer families

High serum levels of insulin-like growth factor I (IGF-I) are associated with an increased risk of sporadic breast cancer (BC). The aim of the present work is to evaluate the association between IGF-I and hereditary BC risk, using a case-control approach. The work represents an "ad interim" cross-sectional analysis of an ongoing study with a prospective design whose aim is to recruit a cohort of women belonging to high genetic risk families to test potential modulators of penetrance and prognosis. The odd of exposure to high serum IGF-I levels among women with a previous diagnosis of BC ("cases") was compared with the odd among unaffected "controls". The odds ratio (OR) and 95% confidence intervals (CIs) were estimated by unconditional logistic regression, controlling for confounders. We analysed 308 women (209 cases and 99 controls) at high genetic risk of BC. The adjusted OR of BC for the upper tertile of serum IGF-I versus the lowest one was 3.5 (95%CI 1.4-8.8). Excluding from the analysis 64 women under current Tamoxifen or GnRH analogues treatment, the adjusted OR of BC became 3.7 (95%CI 1.4-9.9). The association became stronger restricting the analysis to the 161 women (97 cases and 64 controls) with a proven BRCA mutation. If confirmed by a prospective approach, the association between IGF-I and familial BC will open further options for reducing BC risk in susceptible women.

Breast cancer patients with lobular cancer more commonly have a father than a mother diagnosed with cancer

BACKGROUND

The association between lobular breast cancer and family history is not clear. The aim of the study was to possibly identifying new hereditary patterns predisposing for cancer in the different histopathologic subtypes of breast cancer, with focus on patients with lobular breast cancer and cancer in their first degree relatives.

METHODS

In 1676 consecutive breast cancer patients detailed family history of cancer was related to histopathologic subtype of breast cancer.

RESULTS

Patients with lobular breast cancer were found to be significantly positively associated with having a father diagnosed with cancer, OR 2.17 (95% confidence interval (CI) 1.37-3.46). The finding persisted after excluding breast cancer in the family. Ductal breast cancer was associated with having a mother diagnosed with cancer. There was a significant association between lobular breast cancer and having a father with prostate cancer, OR 2.4 (CI 1.1-5.3). The occurrence of having a father with prostate cancer for lobular breast cancer patients was higher in the younger patient group, OR 2.9 (CI 1.1-7.8), and was still high but lost statistical significance in the older patient group, OR 1.9 (CI 0.5-7.4). The association between lobular breast cancer and a father remained significant after excluding fathers with prostate cancer, OR 1.94 (CI 1.20-3.14). Other commonly occurring tumor types in the father included sarcoma and leukemia.

CONCLUSION

We propose that lobular breast cancer is associated with having a father diagnosed with cancer, most commonly prostate carcinoma. Since the association remained after excluding family history of breast cancer, the association seems independent of classical breast cancer heredity. The association with a father diagnosed with cancer also remained after removing prostate cancer, indicating an independence from prostate cancer as well. The reason for this association is genetically unclear, but could involve sex-specific imprinting.

Family history of breast cancer in relation to tumor characteristics and mortality in a population-based study of young women with invasive breast cancer

BACKGROUND

Inherited predisposition may be associated with distinctive breast cancer phenotypes and/or mortality. Past studies have had inconsistent results and little is known about the contributions of screening and treatment.

METHODS

Within a population-based cohort of 1,260 women diagnosed with invasive breast cancer before age 46, we assessed how family history of breast cancer relates to mortality and tumor characteristics. Analyses were repeated excluding BRCA1/BRCA2 carriers. Medical records were reviewed for treatment history and tumors were centrally reviewed and tested. Cox proportional hazard modeling was used to assess the risk of dying in relation to family history; logistic regression was used to assess the association of family history to tumor characteristics.

RESULTS

Compared with women with no family history, women with first-degree family history of breast cancer had a 40% reduction (95% CI: 0.5-0.8) in the risk of dying. Mortality in women with only a second-degree family history was similar to those with no family history. The risk of dying was further reduced in those with a greater number of affected relatives. These relationships did not seem to be attributable to differences in screening, detection method, or treatment. Tumors in women with a first-degree family history had generally more favorable prognostic profiles.

CONCLUSION

Our findings suggest that breast cancer patients with a first-degree family history, compared with their counterparts without such a profile, may have a better prognosis.

IMPACT

These findings support the need for future research directed at replicating these results and identifying factors underlying this possible relationship.

BRCA1 and BRCA2 families and the risk of skin cancer

BRCA1 and BRCA2 mutation carriers have elevated risks of breast and ovarian cancers. The risks for cancers at other sites remain unclear. Melanoma has been associated with BRCA2 mutations in some studies, however, few surveys have included non-melanoma skin cancer. We followed 2729 women with a BRCA1 or BRCA2 mutation for an average of 5.0 years. These women were asked to report new cases of cancer diagnosed in themselves or in their family. The risks of skin cancer were compared for probands with BRCA1 and BRCA2 mutations. Of 1779 women with a BRCA1 mutation, 29 developed skin cancer in the follow-up period (1.6%). Of the 950 women with a BRCA2 mutation, 28 developed skin cancer (3.0%) (OR = 1.83 for BRCA2 versus BRCA1; 95% CI 1.08-3.10; P = 0.02). The odds ratio for basal cell carcinoma was higher (OR = 3.8; 95% CI 1.5-9.4; P = 0.002). BRCA2 mutation carriers are at increased risk for skin cancer, compared with BRCA1 carriers, in particular for basal cell carcinoma.

Genetic testing and first presymptomatic diagnosis in Moroccan families at high risk for breast/ovarian cancer

Germline mutations in the BRCA1 and BRCA2 genes highly predispose to breast and ovarian cancers and are responsible for a substantial proportion of familial breast and ovarian cancers. No female individuals from families from Morocco affected by breast cancer with mutations of these genes have previously been reported, and clinicians in Morocco are unaccustomed to dealing with healthy female individuals carrying mutations in the BRCA genes. This study aimed to report the initial experience of a group of Moroccan investigators carrying out predictive genetic testing to detect a known familial mutation in healthy Moroccan females with a high risk of developing breast cancer and to introduce supervision of these asymptomatic female carriers as a new approach in the prevention and early diagnosis of breast and ovarian cancers in Morocco. Presymptomatic diagnosis was carried out using DNA genetic testing in 5 healthy Moroccan female individuals from three families with an elevated risk of developing breast cancer. These are the first Moroccan families reported to be affected by breast cancers associated with BRCA mutations. Presymptomatic diagnosis was carried out for breast cancer in 5 female individuals from three Moroccan families with BRCA mutations. Two of the families are the first reported incidence of the founder mutation Ashkenazi BRCA1-185_186delAG in Moroccan patients. The third family carried the known BRCA2 mutation c.5073dupA/p.trp1692metfsX3. We tested the presence of these mutations in 5 asymptomatic healthy females from the three families. Two sisters from family 1 carried the BRCA1-185_186delAG mutation, whereas the third female individual from family 2 carried the c.5073dupA/p.trp1692metfsX3 mutation. However, one healthy female individual and her mother from family 3 did not carry the familial mutation of the BRCA1 gene. This study found BRCA mutations in three asymptomatic subjects, suggesting that this is the first step towards the development of persistent medical monitoring of females from families with a history of breast and ovarian cancers. Consequently, it is crucial for oncologists in Morocco to initiate the supervision of healthy female individuals with genetic defects which may lead to hereditary cancers.

Presymptomatic breast cancer in Egypt: role of BRCA1 and BRCA2 tumor suppressor genes mutations detection

BACKGROUND

Breast cancer is one of the most common diseases affecting women. Inherited susceptibility genes, BRCA1 and BRCA2, are considered in breast, ovarian and other common cancers etiology. BRCA1 and BRCA2 genes have been identified that confer a high degree of breast cancer risk.

OBJECTIVE

Our study was performed to identify germline mutations in some exons of BRCA1 and BRCA2 genes for the early detection of presymptomatic breast cancer in females.

METHODS

This study was applied on Egyptian healthy females who first degree relatives to those, with or without a family history, infected with breast cancer. Sixty breast cancer patients, derived from 60 families, were selected for molecular genetic testing of BRCA1 and BRCA2 genes. The study also included 120 healthy first degree female relatives of the patients, either sisters and/or daughters, for early detection of presymptomatic breast cancer mutation carriers. Genomic DNA was extracted from peripheral blood lymphocytes of all the studied subjects. Universal primers were used to amplify four regions of the BRCA1 gene (exons 2,8,13 and 22) and one region (exon 9) of BRCA2 gene using specific PCR. The polymerase chain reaction was carried out. Single strand conformation polymorphism assay and heteroduplex analysis were used to screen for mutations in the studied exons. In addition, DNA sequencing of the normal and mutated exons were performed.

RESULTS

Mutations in both BRCA1 and BRCA2 genes were detected in 86.7% of the families. Current study indicates that 60% of these families were attributable to BRCA1 mutations, while 26.7% of them were attributable to BRCA2 mutations. Results showed that four mutations were detected in the BRCA1 gene, while one mutation was detected in the BRCA2 gene. Asymptomatic relatives, 80 (67%) out of total 120, were mutation carriers.

CONCLUSIONS

BRCA1 and BRCA2 genes mutations are responsible for a significant proportion of breast cancer. BRCA mutations were found in individuals with and without family history.

Familial and sporadic breast cancers: differences in clinical, histopathological, and immunohistochemical features

In the present study, the authors investigated the clinical, histopathological, and immunohistochemical features in familial breast cancer (FBC) patients and compared them with findings in sporadic breast cancers (SBCs); hormone receptor status was stratified by age. A total of 849 patients treated for breast cancer were included in the study. The patients were stratified into 2 groups: FBC, 160 patients (19%), and SBC, 689 patients (81%). FBC tumors differed from SBC tumors by earlier age of diagnosis and low content of progesterone receptor (PR). These characteristics should be of value in evaluating the possibility of mutation and in targeting mutation screening in such families. PR gene polymorphism leads to an increased risk of breast cancer because it determines inadequate control of estrogen receptor (ER)-driven proliferative function. ER+/PR- tumors more frequently showed HER2 (human epidermal growth factor receptor) overexpression and represent a distinct subset in FBC patients. The authors suggest that late-onset FBCs need more intensive therapy and a more careful follow-up.

A pilot genome-wide association study of early-onset breast cancer

High-density oligonucleotide microarrays containing a large number of single nucleotide polymorphisms (SNPs) have enabled genome-wide association (GWA) analysis to become a reality. We used the early access Affymetrix Mendel Nsp 250K chips in a GWA case-control pilot study to identify genomic regions associated with breast cancer. We included 30 randomly sampled incident invasive breast cancer cases aged <45 years without deleterious mutations in the BRCA1 or BRCA2 genes, and 30 population controls individually matched on age, ethnicity and geographical area. The overall genotype call rate was 97.13+/-1.33% for controls and 97.48+/-1.42% for cases. Comparison was made between cases and controls for 203,477 genotyped SNPs using (a) unconditional logistic regression (ULR), (b) conditional logistic regression (CLR) models with adjustment for the matched pairs, (c) allelic tests for single marker tests and (d) haplotype trend regression (HTR). Genomic control and EIGENSTRAT methods were used for correction of population stratification in appropriate models. We demonstrate the similarity and dissimilarity of results from different statistical analyses. We found several possible significant regions harboring biologically meaningful known candidate genes, such as genes encoding fibroblast growth factor, transforming growth factor, epidermal growth factor, and estrogen synthesis enzymes to be associated with early-onset breast cancer. In single marker analysis, none of the SNPs were statistically significant after correction for multiple testing. However, haplotype association tests, using 90730 tag-SNPs, suggested two regions in GLG1 and UGT1 genes retaining significance even after Bonferroni correction. Nevertheless, without systematic replication, findings from this pilot study, especially the associations of breast cancer in relation to specific SNPs, should be interpreted with great caution.

Associations of high-grade prostate cancer with BRCA1 and BRCA2 founder mutations

PURPOSE

Protein-truncating mutations in BRCA1 and in particular BRCA2 genes have been associated with prostate cancer. However, there is still uncertainty about the magnitude of association particularly with Gleason score, and family history of prostate, breast, and ovary cancers.

EXPERIMENTAL DESIGN

To further examine associations between three founder mutations located in BRCA1 (185delAG, 5382insC) or BRCA2 (6174delT) genes and prostate cancer, we conducted a study of 979 prostate cancer cases and 1,251 controls among Ashkenazi Jewish men. Detailed information was obtained on prostate cancer pathology, age at diagnosis, and family history of all cancers. Odds ratios (OR) and 95% confidence intervals (CIs) were estimated using logistic regression models.

RESULTS

Prostate cancer risk was increased (OR, 1.9; 95% CI 0.9-4.1) for BRCA2 mutation carriers but not for BRCA1 mutation carriers. BRCA2 mutation carriers had an OR of 3.2 (95% CI, 1.4-7.3) for Gleason score of 7 to 10, but no association was observed for Gleason score of < 7. Carriers of BRCA1-185delAG mutation also had an OR of 3.5 (95% CI, 1.2-10.3) for Gleason score of > or =7 tumors; however, the association of either BRCA1-185delAG or 5382insC mutation was not statistically significant. Associations between founder mutations and prostate cancer were stronger in men with no first-degree family history of breast and/or ovarian cancers but were unaffected by family history of prostate cancer.

CONCLUSION

These results indicate that the BRCA2 founder mutation confers a 3-fold elevated risk of high-grade prostate cancer. Although BRCA1 mutations were not associated with prostate cancer, the BRCA1-185delAG was associated with high Gleason score tumors. These findings should be carefully considered in genetic counseling and/or evaluating therapeutic options.

The role of the BRCA2 gene in susceptibility to prostate cancer revisited

Prostate cancer is a genetically complex disease with multiple predisposing factors affecting presentation, progression, and outcome. Epidemiologic studies have long shown an aggregation of breast and prostate cancer in some families. More recently, studies have reported an apparent excess of prostate cancer cases among BRCA2 mutation-carrying families. Additionally, population-based screens of early-onset prostate cancer patients have suggested that the prevalence of deleterious BRCA2 mutations in this group is 1% to 2%, imparting a significantly increased risk of the disease compared with noncarrier cases. However, studies of high-risk prostate cancer families suggest that BRCA2 plays at most a minimal role in these individuals, highlighting the potential genetic heterogeneity of the disease. In this commentary, we review the current literature and hypotheses surrounding the relationship between BRCA2 mutations and susceptibility to prostate cancer and speculate on the potential for involvement of additional genes.

Genetic counselling and testing for inherited gene mutations in newly diagnosed patients with breast cancer: a review of the existing literature and a proposed research agenda

Many women newly diagnosed with breast cancer and with a strong family history of breast cancer are referred to a family cancer service for genetic counselling and for consideration of genetic testing for germline mutations in cancer predisposition genes following completion of their cancer treatment. However, there is growing evidence that mutation status may influence treatment recommendations, and that there may be benefits in having 'treatment-focused genetic counselling and testing' available shortly after cancer diagnosis. This article reviews the literature that could inform the development of treatment-focused genetic counselling and testing, including: the rationale for genetic testing to aid with treatment decisions; the potential benefits of using mutation or risk status to tailor management; the criteria that may be used to identify patients most likely to carry germline mutations; and the evidence regarding women's decision-making regarding treatment-focused genetic counselling and testing and the associated psychological impact.

Rare germline mutations in the BRCA2 gene are associated with early-onset prostate cancer

Studies of families who segregate BRCA2 mutations have found that men who carry disease-associated mutations have an increased risk of prostate cancer, particularly early-onset disease. A study of sporadic prostate cancer in the UK reported a prevalence of 2.3% for protein-truncating BRCA2 mutations among patients diagnosed at ages ⩽55 years, highlighting the potential importance of this gene in prostate cancer susceptibility. To examine the role of protein-truncating BRCA2 mutations in relation to early-onset prostate cancer in a US population, 290 population-based patients from King County, Washington, diagnosed at ages <55 years were screened for germline BRCA2 mutations. The coding regions, intron–exon boundaries, and potential regulatory elements of the BRCA2 gene were sequenced. Two distinct protein-truncating BRCA2 mutations were identified in exon 11 in two patients. Both cases were Caucasian, yielding a mutation prevalence of 0.78% (95% confidence interval (95%CI) 0.09–2.81%) and a relative risk (RR) of 7.8 (95%CI 1.8–9.4) for early-onset prostate cancer in white men carrying a protein-truncating BRCA2 mutation. Results suggest that protein-truncating BRCA2 mutations confer an elevated RR of early-onset prostate cancer. However, we estimate that <1% of early-onset prostate cancers in the general US Caucasian population can be attributed to these rare disease-associated BRCA2 mutations.

Multivariate logistic regression for familial aggregation in age at disease onset

Familial aggregation studies seek to identify diseases that cluster in families. These studies are often carried out as a first step in the search for hereditary factors affecting the risk of disease. It is necessary to account for age at disease onset to avoid potential misclassification of family members who are disease-free at the time of study participation or who die before developing disease. This is especially true for late-onset diseases, such as prostate cancer or Alzheimer's disease. We propose a discrete time model that accounts for the age at disease onset and allows the familial association to vary with age and to be modified by covariates, such as pedigree relationship. The parameters of the model have interpretations as conditional log-odds and log-odds ratios, which can be viewed as discrete time conditional cross hazard ratios. These interpretations are appealing for cancer risk assessment. Properties of this model are explored in simulation studies, and the method is applied to a large family study of cancer conducted by the National Cancer Institute-sponsored Cancer Genetics Network (CGN).

Germline mutations in the BRCA2 gene and susceptibility to hereditary prostate cancer

PURPOSE

Several epidemiologic studies have reported that carriers of germline mutations in the BRCA2 gene have an increased risk of prostate cancer, with the highest risk observed in men diagnosed at earlier ages. However, studies of the contribution of BRCA2 mutations to the etiology of hereditary prostate cancer (HPC) have been inconsistent.

EXPERIMENTAL DESIGN

To further address this issue, 266 subjects from 194 HPC families participating in the Seattle-based Prostate Cancer Genetic Research Study were screened for BRCA2 mutations by sequencing the coding regions, intron-exon boundaries, and suspected regulatory elements of this gene. Of selected HPC families, 32 had multiple breast or ovarian cancer cases, 16 were Jewish, 8 had a pancreatic cancer case, and 138 had at least one affected man diagnosed with prostate cancer at an early age (<60 years).

RESULTS

No disease-associated protein truncating BRCA2 mutations were found in 266 subjects from HPC families. There were 61 DNA sequence variants, of which 31 (50.8%) changed the predicted amino acids. No associations were found between these missense changes and family characteristics. Among affected men with prostate cancer, there were no statistically significant differences between the genotype frequencies of DNA variants with a minor allele frequency of 1% or higher and between the strata defined by median age at diagnosis or by clinical features.

CONCLUSION

No evidence was found in this study for an association between BRCA2 mutations and susceptibility to HPC in men selected from high-risk families.

Novel germline BRCA1 and BRCA2 mutations in Turkish women with breast and/or ovarian cancer and their relatives

BRCA1 and BRCA2 gene mutations in patients with breast and/or ovarian cancer have been not characterized in the Turkish population until now. A total of 87 female subjects from two sets of families (38 families total) provided blood samples from which DNA was extracted. All coding exons of the BRCA1 and BRCA2 genes were screened for mutations with heteroduplex analysis and sequencing. Fourteen of the families (49 subjects comprising 17 patients and 32 unaffected relatives) had at least 2 women affected by breast and/or ovarian cancer. The other 24 families (38 subjects unaffected by breast and/or ovarian cancer) also had a history of these 2 forms of cancer. Six different sequence variants were detected: one previously described truncating mutation (5382insC) and one novel polymorphism (3663C-->A) in BRCA1, and 2 novel truncating mutations (9329insC and 9934insG), one novel intronic polymorphism 7069+41(TTTT-->AAAG), and one previously reported global polymorphism (1093A-->C) in BRCA2. BRCAPRO software was used for analysis, and the results showed that the level of risk for both breast and ovarian cancer increased with age in women who carried the mutation. In conclusion, these findings contribute significantly to what currently is known about the types and impact of germline BRCA1 and BRCA2 mutations in Turkish women.

An observational study of cancers among female partners of UK-resident prostate cancer patients

Epidemiological studies suggest that environment plays an important role in the aetiology of cancer. Thus, if a cancer (e.g. prostate cancer (CaP)) arises in males, one could hypothesize that risk in co-habiting partners might be elevated. We conducted an observational-questionnaire study in NorthWest England evaluating the medical histories of CaP males and their female partners. Details regarding previous partners (>10y) were also sought. Self-filled questionnaires were obtained from 548 males, 81 of whom provided information on previous female partners (PFPs) and 448 current female partners (CFPs). Observed rates over a 30-y period (1971-2001) of common cancers (breast, colorectal or lung) in female partners and colorectal cancer in males were compared to the cumulative expected probability (estimated using crude incidence rates for England provided by the Office of National Statistics, UK) using a Chi-Square Goodness-of-Fit test. Colorectal cancers in males were similar to national estimates. Rates for breast, colorectal or lung cancer among CFPs and the total female cohort (CFPs plus PFPs) were also similar to estimates. However, observed rates for breast or lung cancers among PFPs were significantly (P< or =0.001) elevated. Our results suggest no evidence of elevated risk among female partners of CaP males.

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.

Breast and ovarian cancer in relatives of cancer patients, with and without BRCA mutations

BACKGROUND

First-degree relatives of patients with breast or ovarian cancer have increased risks for these cancers. Little is known about how their risks vary with the patient's cancer site, carrier status for predisposing genetic mutations, or age at cancer diagnosis.

METHODS

We evaluated breast and ovarian cancer incidence in 2,935 female first-degree relatives of non-Hispanic White female patients with incident invasive cancers of the breast (n = 669) or ovary (n = 339) who were recruited from a population-based cancer registry in northern California. Breast cancer patients were tested for BRCA1 and BRCA2 mutations. Ovarian cancer patients were tested for BRCA1 mutations. We estimated standardized incidence ratios (SIR) and 95% confidence intervals (95% CI) for breast and ovarian cancer among the relatives according to the patient's mutation status, cancer site, and age at cancer diagnosis.

RESULTS

In families of patients who were negative or untested for BRCA1 or BRCA2 mutations, risks were elevated only for the patient's cancer site. The breast cancer SIR was 1.5 (95% CI, 1.2-1.8) for relatives of breast cancer patients, compared with 1.1 (95% CI, 0.8-1.6) for relatives of ovarian cancer patients (P = 0.12 for difference by patient's cancer site). The ovarian cancer SIR was 0.9 (95% CI, 0.5-1.4) for relatives of breast cancer patients, compared with 1.9 (95% CI, 1.0-4.0) for relatives of ovarian cancer patients (P = 0.04 for difference by site). In families of BRCA1-positive patients, relatives' risks also correlated with the patient's cancer site. The breast cancer SIR was 10.6 (95% CI, 5.2-21.6) for relatives of breast cancer patients, compared with 3.3 (95% CI, 1.4-7.3) for relatives of ovarian cancer patients (two-sided P = 0.02 for difference by site). The ovarian cancer SIR was 7.9 (95% CI, 1.2-53.0) for relatives of breast cancer patients, compared with 11.3 (3.6-35.9) for relatives of ovarian cancer patients (two-sided P = 0.37 for difference by site). Relatives' risks were independent of patients' ages at diagnosis, with one exception: In families ascertained through a breast cancer patient without BRCA mutations, breast cancer risks were higher if the patient had been diagnosed before age 40 years.

CONCLUSION

In families of patients with and without BRCA1 mutations, breast and ovarian cancer risks correlate with the patient's cancer site. Moreover, in families of breast cancer patients without BRCA mutations, breast cancer risk depends on the patient's age at diagnosis. These patterns support the presence of genes that modify risk specific to cancer site, in both carriers and noncarriers of BRCA1 and BRCA2 mutations.

Use of biomarkers to elucidate genetic susceptibility to cancer

Genetic variations have generally been accepted to be the major mechanism for the differences observed in susceptibility to cancer. However, extensive investigations on genotype-disease associations have not produced consistent results. The inconsistency may be caused by many factors, such as improper study design, insufficient sample size, complexity of the traits under investigation, heterogeneity of the study subjects, incorrect assumptions about the underlying genetic architecture, misclassification of the disease, improper selection of potential alleles, and overinterpretation of the data. Besides these "traditional" factors, a recent problem is that the function of many variant genotypes is unknown, especially with regard to polymorphic DNA repair genes. Therefore, in addition to the genotype-disease relationship, it may be prudent to step back and investigate the fundamental role of genetic variation in the development of cancer. The latter studies may focus on understanding the genotype-exposure interactions and evaluating genotype-health risk associations. This review will emphasize the use of relevant biomarkers and polymorphic DNA repair genes for investigations. These data will be useful for a better understanding of the complexity of disease causation and development, developing new models for human disease, and identifying pathways for prevention of cancer.

A population-based assessment of the clustering of breast cancer in families eligible for testing of BRCA1 and BRCA2 mutations

BACKGROUND

The prevalence of families eligible for BRCA1/2 mutation testing in the population burden of breast cancer was analysed and the aggregation of breast cancer in these families was explored.

PATIENTS AND METHODS

The families of the Swedish Family-Cancer Database with at least three generations (N=944 723) were classified according to the criteria proposed by the German Consortium for Hereditary Breast and Ovarian Cancer for BRCA1/2 mutation testing. We calculated the proportion of women with breast cancer in the classified families and used standardised incidence ratios (SIRs) to estimate the risk of histology specific breast cancers in families with suspected BRCA1/2 mutations.

RESULTS

Families with two breast cancers before the age of 50 years included 1.8% of the breast cancer patients; 1% of the women with breast cancer belonged to families with breast and ovarian cancers. The SIR of female breast cancer was lowest in families with male breast cancer and highest in families with two women affected by breast cancer under the age of 50 years. The SIRs of medullary breast cancer agreed with the BRCA1 mutation prevalences detected by the German Consortium for Hereditary Breast and Ovarian Cancer.

CONCLUSIONS

Most of the breast malignancies in families with male breast cancer are likely to be related to BRCA2 mutations. Non-BRCA1/2 related effects are probably involved in the strong clustering of breast cancer in families with early onset breast and ovarian cancers.

Cancer as a complex phenotype: pattern of cancer distribution within and beyond the nuclear family

BACKGROUND

The contribution of low-penetrant susceptibility variants to cancer is not clear. With the aim of searching for genetic factors that contribute to cancer at one or more sites in the body, we have analyzed familial aggregation of cancer in extended families based on all cancer cases diagnosed in Iceland over almost half a century.

METHODS AND FINDINGS

We have estimated risk ratios (RRs) of cancer for first- and up to fifth-degree relatives both within and between all types of cancers diagnosed in Iceland from 1955 to 2002 by linking patient information from the Icelandic Cancer Registry to an extensive genealogical database, containing all living Icelanders and most of their ancestors since the settlement of Iceland. We evaluated the significance of the familial clustering for each relationship separately, all relationships combined (first- to fifth-degree relatives) and for close (first- and second-degree) and distant (third- to fifth-degree) relatives. Most cancer sites demonstrate a significantly increased RR for the same cancer, beyond the nuclear family. Significantly increased familial clustering between different cancer sites is also documented in both close and distant relatives. Some of these associations have been suggested previously but others not.

CONCLUSION

We conclude that genetic factors are involved in the etiology of many cancers and that these factors are in some cases shared by different cancer sites. However, a significantly increased RR conferred upon mates of patients with cancer at some sites indicates that shared environment or nonrandom mating for certain risk factors also play a role in the familial clustering of cancer. Our results indicate that cancer is a complex, often non-site-specific disease for which increased risk extends beyond the nuclear family.

Contribution of the Defective BRCA1, BRCA2 and CHEK2 Genes to the Familial Aggregation of Breast Cancer: a Simulation Study Based on the Swedish Family-Cancer Database

The known breast cancer susceptibility genes only account for 20% to 25% of the excess familial risk of the disease [1]. The present study assessed the contribution of BRCA1/2 mutations and CHEK2 variants to the relative risk of breast cancer for women with affected mothers or sisters. The familial relative risks were estimated by Poisson regression based on the Swedish Family-Cancer Database. The Database was also used to calculate the distribution of life expectancy, the number of daughters per family and the age specific cumulative risk of female breast cancer. This information, together with the penetrances of BRCA1, BRCA2 and CHEK2 from the literature, was used to simulate the familial clustering of breast cancer under different scenarios. The excess risk explained by BRCA1, BRCA2 and CHEK2 decreased steeply with the age at diagnosis of the cancers. Around 40% of the familial risk for cases diagnosed before the age of 50 years was associated with BRCA1/2 mutations. In contrast, roughly 85% of the familial risk of breast cancer diagnosed before the age of 69 years remained unexplained. The contribution of CHEK2 to familial breast cancer was small.