Risk modifiers in carriers of BRCA1 mutations

The risks of cancer in older women with BRCA pathogenic variants: How far have we come?

BACKGROUND

The purpose of this study was to estimate the cumulative risks of all cancers in women from 50 to 75 years of age with a BRCA1 or BRCA2 pathogenic variant.

METHODS

Participants were women with BRCA1 or BRCA2 pathogenic variants from 85 centers in 16 countries. Women were eligible if they had no cancer before the age of 50 years. Participants completed a baseline questionnaire and follow-up questionnaires every 2 years. Women were followed from age 50 until a diagnosis of cancer, death, age 75, or last follow-up. The risk of all cancers combined from age 50 to 75 was estimated using the Kaplan-Meier method.

RESULTS

There were 2211 women included (1470 BRCA1 and 742 BRCA2). There were 379 cancers diagnosed in the cohort between 50 and 75 years. The actuarial risk of any cancer from age 50 to 75 was 49% for BRCA1 and 43% for BRCA2. Breast (n = 186) and ovarian (n = 45) were the most frequent cancers observed. For women who had both risk-reducing mastectomy and bilateral salpingo-oophorectomy before age 50, the risk of developing any cancer between age 50 and 75 was 9%.

CONCLUSION

Women with a BRCA1 or BRCA2 pathogenic variant have a high risk of cancer between the ages of 50 and 75 years and should be counselled appropriately.

Breast cancer risk in BRCA1/2 mutation carriers and noncarriers under prospective intensified surveillance

Comparably little is known about breast cancer (BC) risks in women from families tested negative for BRCA1/2 mutations despite an indicative family history, as opposed to BRCA1/2 mutation carriers. We determined the age-dependent risks of first and contralateral breast cancer (FBC, CBC) both in noncarriers and carriers of BRCA1/2 mutations, who participated in an intensified breast imaging surveillance program. The study was conducted between January 1, 2005, and September 30, 2017, at 12 university centers of the German Consortium for Hereditary Breast and Ovarian Cancer. Two cohorts were prospectively followed up for incident FBC (n = 4,380; 16,398 person-years [PY], median baseline age: 39 years) and CBC (n = 2,993; 10,090 PY, median baseline age: 42 years). Cumulative FBC risk at age 60 was 61.8% (95% CI 52.8-70.9%) for BRCA1 mutation carriers, 43.2% (95% CI 32.1-56.3%) for BRCA2 mutation carriers and 15.7% (95% CI 11.9-20.4%) for noncarriers. FBC risks were significantly higher than in the general population, with incidence rate ratios of 23.9 (95% CI 18.9-29.8) for BRCA1 mutation carriers, 13.5 (95% CI 9.2-19.1) for BRCA2 mutation carriers and 4.9 (95% CI 3.8-6.3) for BRCA1/2 noncarriers. Cumulative CBC risk 10 years after FBC was 25.1% (95% CI 19.6-31.9%) for BRCA1 mutation carriers, 6.6% (95% CI 3.4-12.5%) for BRCA2 mutation carriers and 3.6% (95% CI 2.2-5.7%) for noncarriers. CBC risk in noncarriers was similar to women with unilateral BC from the general population. Further studies are needed to confirm whether less intensified surveillance is justified in women from BRCA1/2 negative families with elevated risk.

Breast Cancer and Pregnancy

The diagnosis of breast cancer during pregnancy is a rare event, but the young age of the patient together with the emotional impact for both the family and the doctors make therapeutic choices usually very difficult. Until recently, the occurrence of pregnancy associated breast cancer was thought to hold a grave prognosis and therapeutic abortion was very often advised in common practice. The hormonal environment with the increase in estrogens and progesterone was the main factor for the fear of tumor stimulation. The course of breast cancer, however, does not appear to be adversely affected by continuation of pregnancy. In the last years it was realized that potentially curative therapies can be administered even when pregnancy is continued. Of course in the medical literature there is no randomized clinical trial helping in taking decision in this setting; however, a significant experience already exists in some institutions and can guide management in these difficult cases.

The aim of our review is to give an answer to questions usually coming from various specialists who collaborate with the oncologists in treating these patients and furthermore to try and find some basic guidelines which can be used in the information of the patients regarding previous experience in this field.

The problem of a pregnancy after treatment for breast cancer is also analyzed, as this aspect is an emerging issue in clinical oncology. The decision should be evaluated for each single patient, taking into account the prognosis of the patient and her desire of pregnancy.

The Genetics of Breast Cancer: What the Surgical Oncologist Needs to Know

This article summarizes the impact of germline predisposition to breast cancer on the surgical management of breast cancer and breast cancer risk. Surgical implications of germline predisposition to breast cancer are now more nuanced due to the application of increasingly more complicated next-generation sequencing-based tests. The rapid pace of change will continue to challenge paradigms for genetic cancer risk assessment, which can influence the medical and surgical management of breast cancer risk as well as strategies for screening and for risk reduction.

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.

Familiärer Brustkrebs – empirische Erkrankungsrisiken und Risikoberechnungsmodelle

BRCA1/2-Anlageträgerinnen haben ein stark erhöhtes Risiko an Brust- und Eierstockkrebs zu erkranken. Die individuelle klinische Betreuung erfordert eine genaue Kenntnis der Erkrankungsrisiken. In diesem Artikel geben wir einen Überblick über die aktuelle Literatur zu empirischen Erkrankungsrisiken, und wir beschreiben Berechnungsmodelle, die derzeit in der klinischen Praxis für die individuelle Risikoeinschätzung genutzt werden.

Die in der Literatur beschriebenen Erkrankungsrisiken zeigen eine große Variabilität zwischen verschiedenen Studien. Das Brustkrebsrisiko beträgt 40–87 % bei BRCA1- und 18–88 % bei BRCA2-Anlageträgerinnen. Für den Eierstockkrebs werden Risiken von 22–65 % bei BRCA1- und 10–35 % bei BRCA2-Anlageträgerinnen angegeben. Auch das kumulative Risiko für kontralateralen Brustkrebs 10 Jahre nach der Ersterkrankung ist mit 27 % (BRCA1) und 19 % (BRCA2) deutlich erhöht. Verschiedene Berechnungsmodelle erlauben eine individuelle Risikovorhersage, indem zusätzlich die jeweilige Familienanamnese, bekannte Hauptgene und ihr Erbgang sowie andere genetische und epidemiologische Risikofaktoren berücksichtigt werden. Durch nutzerfreundliche Programme können diese Modelle direkt in der humangenetischen und klinischen Beratung angewandt werden. Für die genaue Bestimmung von Erkrankungsrisiken sowie für die Validierung der Risikovorhersagemodelle sind prospektive Kohortenstudien von großer Bedeutung. Um Studien dieser Art zu ermöglichen, sollten Frauen mit erhöhtem Risiko im Rahmen von strukturierten Registerstudien betreut und prospektiv nachverfolgt werden.

Breast cancer risks and risk prediction models

BRCA1/2 mutation carriers have a considerably increased risk to develop breast and ovarian cancer. The personalized clinical management of carriers and other at-risk individuals depends on precise knowledge of the cancer risks. In this report, we give an overview of the present literature on empirical cancer risks, and we describe risk prediction models that are currently used for individual risk assessment in clinical practice. Cancer risks show large variability between studies. Breast cancer risks are at 40-87% for BRCA1 mutation carriers and 18-88% for BRCA2 mutation carriers. For ovarian cancer, the risk estimates are in the range of 22-65% for BRCA1 and 10-35% for BRCA2. The contralateral breast cancer risk is high (10-year risk after first cancer 27% for BRCA1 and 19% for BRCA2). Risk prediction models have been proposed to provide more individualized risk prediction, using additional knowledge on family history, mode of inheritance of major genes, and other genetic and non-genetic risk factors. User-friendly software tools have been developed that serve as basis for decision-making in family counseling units. In conclusion, further assessment of cancer risks and model validation is needed, ideally based on prospective cohort studies. To obtain such data, clinical management of carriers and other at-risk individuals should always be accompanied by standardized scientific documentation.

BRCA1 and BRCA2 Gene Mutations Screening In Sporadic Breast Cancer Patients In Kazakhstan

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 Kazakhstan women.

AIM

To evaluate the role of BRCA1/2 mutations in Kazakhstan women presenting with sporadic breast cancer.

METHODS

We investigated the distribution and nature of polymorphisms in BRCA1 and BRCA2 entire coding regions in 156 Kazakhstan sporadic breast cancer cases and 112 age-matched controls using automatic direct sequencing.

RESULTS

We identified 22 distinct variants, including 16 missense mutations and 6 polymorphisms in BRCA1/2 genes. In BRCA1, 9 missense mutations and 3 synonymous polymorphisms were observed. In BRCA2, 7 missense mutations and 3 polymorphisms were detected. There was a higher prevalence of observed mutations in Caucasian breast cancer cases compared to Asian cases (p<0.05); higher frequencies of sequence variants were observed in Asian controls. No recurrent or founder mutations were observed in BRCA1/2 genes. There were no statistically significant differences in age at diagnosis, tumor histology, size of tumor, and lymph node involvement between women with breast cancer with or without the BRCA sequence alterations.

CONCLUSIONS

Considering the majority of breast cancer cases are sporadic, the present study will be helpful in the evaluation of the need for the genetic screening of BRCA1/2 mutations and reliable genetic counseling for Kazakhstan sporadic breast cancer patients. Evaluation of common polymorphisms and mutations and breast cancer risk in families with genetic predisposition to breast cancer is ongoing in another current investigation.

Pregnancy after Breast Cancer: Myths and Facts

Most young breast cancer survivors consider reproductive issues to be of great importance, but many questions remain undervalued and unanswered. Overall, available data support the safety and feasibility of pregnancy and breastfeeding after breast cancer. The accuracy of the evidence is however limited by: i) the retrospective and frequently incomplete population-based nature of the data, ii) data not representing the entire population, iii) patient-related effects, iv) underpowered sample size, and v) lack of control for biological factors and risk determinants. We review the available evidence in light of these limitations which outline the need for prospective data collection and focused priority research.

AIB1 polymorphisms with breast cancer susceptibility: a pooled analysis of variation in BRCA1/2 mutation carriers and non-carriers

The AIB1 gene (amplified in breast cancer 1), coding for a member of steroid receptor co-activator p160 protein family is involved in regulation of estrogen receptor transactivation influencing the estrogen-dependent gene expression. It contains a glutamine repeat polymorphism and several single nucleotide polymorphisms that may alter the transcriptional activation of the receptor and affect susceptibility to breast cancer. Previous studies have shown that these polymorphisms may modify the breast cancer risk in women carrying BRCA1/2 mutations. However, the results remained controversial. This meta-analysis of literatures was performed to derive a more precise estimation of the relationship. A total of 22 studies were identified, including 3,742 cases and 3,491 controls for AIB1 polyglutamine repeat polymorphism, 2,170 cases and 3,309 controls for Q586H polymorphism, and 2,183 cases and 3,319 controls for T960T polymorphism. Overall, we found no evidence of association for individuals who carried at least one AIB1 allele of 28 or 29 or more repeat with breast cancer risk. But we found increased breast cancer risk in BRCA1/2 mutation carriers for individuals with both alleles ≥29 polyglutamine repeat (OR, 1.64; 95% CI 1.24-2.17). And reduced risk was found to be associated with the Q586H polymorphism among the variant homozygote genotype carriers (OR, 0.42; 95% CI 0.23-0.77). Our results do not support the direct association of AIB1 polyglutamine repeat length and breast cancer. However, we found that BRCA1/2 mutation carriers with both alleles ≥29 repeats have a higher risk of breast cancer.

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.

Epigenetic targeting in breast cancer: therapeutic impact and future direction

Breast carcinogenesis is a multistep process involving both genetic and epigenetic changes. Epigenetics is defined as a reversible and heritable change in gene expression that is not accompanied by alteration in gene sequence. DNA methylation and histone modifications are the two major epigenetic changes that influence gene expression in cancer. The interaction between methylation and histone modification is intricately orchestrated by the formation of repressor complexes. Several genes involved in proliferation, antiapoptosis, invasion and metastasis have been shown to be methylated in various malignant and premalignant breast neoplasms. The histone deacetylase inhibitors (HDi) have emerged as an important class of drugs to be used synergistically with other systemic therapies in the treatment of breast cancer. Since epigenetic changes are potentially reversible processes, much effort has been directed toward understanding this mechanism with the goal of finding novel therapies as well as more refined diagnostic and prognostic tools in breast cancer.

Effect of reproductive factors and oral contraceptives on breast cancer risk in BRCA1/2 mutation carriers and noncarriers: results from a population-based study

BACKGROUND

Multiparity and breast-feeding reduce breast cancer risk, whereas oral contraceptive use may slightly increase breast cancer risk in the general population. However, the effects of these factors in BRCA1 and BRCA2 mutation carriers are less clear.

METHODS

Case patients were 1,469 women from Los Angeles County ages 20 to 49 years with newly diagnosed breast cancer. Control subjects were 444 women without breast cancer, individually matched to a subset of cases on race, age, and neighborhood. BRCA1/2 genes were sequenced in the cases, and odds ratios of breast cancer associated with various reproductive and hormonal factors in BRCA1/2 mutation carriers and noncarriers were estimated using multivariable logistic regression.

RESULTS

Ninety-four women had a deleterious BRCA1 or BRCA2 mutation. Number of full-term pregnancies was inversely associated with breast cancer risk regardless of BRCA1/2 mutation status. Longer breast-feeding duration was protective among noncarriers but not among mutation carriers; however, this apparent effect modification was not statistically significant (P = 0.23). Neither oral contraceptive use overall nor the use of low-dose oral contraceptives was associated with an increased risk of breast cancer in any subgroup.

CONCLUSIONS

Our results suggest that parity protects against breast cancer in BRCA1/2 mutation carriers, whereas breast-feeding does not. Our data suggest no association between oral contraceptive use and breast cancer risk in BRCA1/2 mutation carriers. Further confirmation that currently available low-dose oral contraceptives do not increase breast cancer risk in carriers is important from a public health perspective given the high prevalence of oral contraceptive use in the United States.

Prediction of BRCA1-association in hereditary non-BRCA1/2 breast carcinomas with array-CGH

BACKGROUND

While new defects in BRCA1 are still being found, it is unclear whether current breast cancer diagnostics misses many BRCA1-associated cases. A reliable test that is able to indicate the involvement of BRCA1 deficiency in cancer genesis could support decision making in genetic counselling and clinical management. To find BRCA1-specific markers and explore the effectiveness of the current diagnostic strategy, we designed a classification method, validated it and examined whether we could find BRCA1-like breast tumours in a group of patients initially diagnosed as non-BRCA1/2 mutation carriers.

METHODS

A classifier was built based on array-CGH profiles of 18 BRCA1-related and 32 control breast tumours, and validated on independent sets of 16 BRCA1-related and 16 control breast carcinomas. Subsequently, we applied the classifier to 48 breast tumours of patients from Hereditary Breast and Ovarian Cancer (HBOC) families in whom no germ line BRCA1/BRCA2 mutations were identified.

RESULTS

The classifier showed an accuracy of 91% when applied to the validation sets. In 48 non-BRCA1/2 patients, only two breast tumours presented a BRCA1-like CGH profile. Additional evidence for BRCA1 dysfunction was found in one of these tumours.

CONCLUSION

We here describe the specific chromosomal aberrations in BRCA1-related breast carcinomas. We developed a predictive genetic test for BRCA1-association and show that BRCA1-related tumours can still be identified in HBOC families after routine DNA diagnostics.

Hereditary ovarian cancer

At least 10% of ovarian tumors are hereditary and associated with highly penetrant, autosomal, dominant genetic predisposition. Three clinical manifestations of hereditary ovarian cancer have been identified: site-specific ovarian cancer, hereditary breast and/or ovarian cancer (HBOC) and hereditary non-polyposis colorectal cancer (HNPCC) syndromes. BRCA germline mutations account for more than 90% of all hereditary epithelial ovarian tumors whereas most of the remaining 10% are caused by MLH1 and MSH2 mutations, which are susceptibility genes of HNPCC. Genetic testing is available for each of the three hereditary syndromes above mentioned. The recommendations for OC surveillance in high-risk women having a strong family history or BRCA mutation carriers include transvaginal pelvic ultrasound with color Doppler and serum CA125 every 6 months. Bilateral salpingo-oophorectomy appears to be effective to reduce the risk of ovarian cancer in BRCA mutation carriers. Hysterosalpingo-oophorectomy should be considered in HNPCC women who undergo surgery for colorectal carcinoma.

Promoter methylation patterns of ATM, ATR, BRCA1, BRCA2 and p53 as putative cancer risk modifiers in Jewish BRCA1/BRCA2 mutation carriers

BRCA1/BRCA2 germline mutations substantially increase breast and ovarian cancer risk, yet penetrance is incomplete. We hypothesized that germline epigenetic gene silencing may affect mutant BRCA1/2 penetrance. To test this notion, we determined the methylation status, using methylation-specific quantitative PCR of the promoter in putative modifier genes: BRCA1, BRCA2, ATM, ATR and P53 in Jewish BRCA1/BRCA2 mutation carriers with (n = 41) or without (n = 48) breast cancer, in sporadic breast cancer (n = 52), and healthy controls (n = 89). Promoter hypermethylation was detected only in the BRCA1 promotor in 5.6-7.3% in each of the four subsets of participants, regardless of health and BRCA1/2 status.Germline promoter hypermethylation in the BRCA1 gene can be detected in about 5% of the female Israeli Jewish population, regardless of the BRCA1/2 status. The significance of this observation is yet to be determined.

Use of association studies to define genetic modifiers of breast cancer risk in BRCA1 and BRCA2 mutation carriers

Though much progress has been made in understanding the role of two major high-risk breast cancer (BC) susceptibility genes, BRCA1 and BRCA2, it remains unclear what causes the observed variation in risk between mutation carriers. This marked variability in individual cancer risk both between and within BRCA1 and BRCA2 mutation carrier families may be partly explained by modifier genes that influence mutation penetrance. Defining these modifiers should help refine individual cancer risk estimates and is also expected to be an efficient method to identify further BC susceptibility alleles in general. This approach is predicated on the concept that variants in genes that are low to moderate penetrance predisposition genes are likely to have a larger risk modification effect in BRCA1/2 mutation carriers. Association studies are usually used to assess the influence of variants in biologically plausible candidate loci on the penetrance of BRCA1/2 mutations (i.e., differences in age of onset or tissue-specificity of disease). Several such modifier loci, including the genes AIB1 and AR involved in hormone metabolism, and the RAD51 gene acting in DNA repair, have been proposed in the literature. A consortium of laboratories (CIMBA) has recently confirmed the RAD51 135 G/C variant as a BC risk modifier in BRCA2 mutation carriers, though not in BRCA1 carriers. This review describes molecular epidemiological efforts to evaluate the potential influence of polymorphic variants in candidate modifier genes on the risk of BC conferred by the BRCA1 and BRCA2 genes.

BRCA1 and BRCA2 status in a Central Sudanese series of breast cancer patients: interactions with genetic, ethnic and reproductive factors

The etiology of breast cancer in Africa is scarcely investigated. Breast cancer was responsible for 456/2,233 cancer patients (20.4%) ascertained between 1999 and 2004 at Gezira University, Central Sudan. Male breast cancer accounted for 16/456 patients (3.5%), 275/440 female patients (62.5%) were premenopausal and 150/440 cases (34%) occurred in women with > or =5 childbirths. We characterized for germline BRCA1/2 mutations a one-year series of patients (34 females, 1 male) selected by diagnosis within age 40 years or male gender. Overall 33/35 patients were found to carry 60 BRCA1/2 variants, of which 17 (28%) were novel, 22 (37%) reported in populations from various geographic areas and 21 (35%) reported worldwide. Detected variants included 5 truncating mutations, one of which (in BRCA2) was in the male patient. The 55 non-truncating variants included 3 unclassified variants predicted to affect protein product and not co-occurring with a truncating mutation in the same gene. Patients were from different tribes but AMOVA showed that most BRCA1/2 variation was within individuals (86.41%) and patients clustered independently of tribe in a phylogenetic tree. Cluster analysis based on age at cancer diagnosis and reproductive variables split female patients in two clusters that, by factor analysis, were explained by low versus high scores of the total period occupied by pregnancies and lactation. The cluster with low scores comprised all 4 patients with truncating mutations and 3 of the 4 carriers of unclassified variants predicted to affect protein product. Our findings suggest that in Central Sudan BRCA1/2 represent an important etiological factor of breast cancer in males and young women less exposed to pregnancy and lactation. Factors other than BRCA1/2 may contribute to breast cancer in young highly multiparous women who breast-fed for prolonged periods.

[Oncogenetic consultation for breast cancer]

Five percent of breast cancers are associated with a genetic predisposition, transmitted as an autosomal dominant trait of either maternal or paternal origin. Mutations of the BRCA1 or BRCA2 genes are associated with a high risk of breast and ovarian cancer and depend in part on these predispositions. The objectives of an oncogenetic consultation are to understand the origin of a personal and family history of breast cancer by using the resources of formal and molecular genetics and to guide the management of the consulting patient and her relatives. The diagnostic genetic test performed from an "index case" is intended to identify genetic alterations specific to each family. The failure to identify a mutation in a diagnostic test does not rule out the existence of a predisposing factor. On the other hand, the identification of a mutation makes it possible to offer a simple test to relatives, and its negative result can provide reassurance. Optimal management of patients with a mutation of the BRCA1 or BRCA2 genes requires frequent clinical examinations and at least annual imaging (mammography, ultrasound or breast MRI as part of a protocol) from the age of 25-30 years. Prophylactic mastectomy may be envisioned. Prophylactic adnexectomy is also usually recommended to prevent ovarian cancer, around the age of 40 years.

Age at first birth and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

An early age at first full-term birth is associated with a reduction in the subsequent development of breast cancer among women in the general population. A similar effect has not yet been reported among women who carry an inherited BRCA1 or BRCA2 mutation. We conducted a matched case-control study on 1816 pairs of women with a BRCA1 (n = 1405) or BRCA2 (n = 411) mutation in an attempt to elucidate the relationship between age at first full-term pregnancy and the risk of developing breast cancer. Information about the age at first childbirth and other pregnancy-related variables was derived from a questionnaire administered to women during the course of genetic counselling. There was no difference in the mean age at first full-term birth in the cases and controls (24.9 years vs. 24.8 years; P = 0.81, respectively). Compared to women whose first child was born at or before 18 years of age, a later age at first full-term birth did not influence the risk of developing breast cancer (OR = 1.00 per year; 95% CI 0.98-1.03; P-trend = 0.67). Stratification by mutation status did not affect the results. These findings suggest that an early first full-term birth does not confer protection against breast cancer in BRCA mutation carriers. Nonetheless, BRCA mutation carriers opting for a prophylactic oophorectomy as a breast and/or ovarian cancer risk-reducing strategy should complete childbearing prior to age 40 when this prevention modality is most effective.

Ovarian cancer

Ovarian cancer accounts for 4% of all cancers in women and is the leading cause of death from gynaecologic malignancies. Because early-stage ovarian cancer is generally asymptomatic, approximately 75% of women present with advanced disease at diagnosis. Survival is highly dependent on stage of disease: 5-year survival in patients with early-stage is 80-90% compared to 25% for patients with advanced-stage disease. For all patients, a comprehensive surgical staging should be performed to obtain the histological confirmation of diagnosis and to evaluate the extent of disease. Patients with early-stage should both be optimally staged and be treated with adjuvant platinum-based chemotherapy if they have a medium or high-risk tumour. For advanced disease the currently recommended management is primary cytoreductive surgery followed by platinum-paclitaxel combination chemotherapy. Appropriate salvage therapy is based on the timing and nature of recurrence and the extent of prior chemotherapy. Surgical resection should be considered in patients with long-term remission, especially in those with isolated recurrences and good performance status. Platinum-based combination represents the standard second-line chemotherapy in patients with platinum-sensitive relapsed ovarian cancer. Salvage chemotherapy in platinum-refractory patients usually results in low response rates and short survival.

BRCA1--a good predictive marker of drug sensitivity in breast cancer treatment?

There are currently only two predictive markers of response to chemotherapy for breast cancer in routine clinical use, namely the Estrogen receptor-alpha and the HER2 receptor. The breast and ovarian cancer susceptibility gene BRCA1 is an important genetic factor in hereditary breast and ovarian cancer and there is increasing evidence of an important role for BRCA1 in the sporadic forms of both cancer types. Our group and numerous others have shown in both preclinical and clinical studies that BRCA1 is an important determinant of chemotherapy responses in breast cancer. In this review we will outline the current understanding of the role of BRCA1 as a determinant of response to DNA damaging and microtubule damaging chemotherapy. We will then discuss how the known functions of this multifaceted protein may provide mechanistic explanations for its role in chemotherapy responses.

Pregnancies, breast-feeding, and breast cancer risk in the International BRCA1/2 Carrier Cohort Study (IBCCS)

BACKGROUND

Multiparity, young age at first childbirth, and breast-feeding are associated with a reduced risk of breast cancer in the general population. The breast cancer predisposition gene, BRCA1, regulates normal cell differentiation. Because mammary gland cells divide and differentiate during pregnancy, reproductive factors may influence breast cancer risk in BRCA1/2 mutation carriers differently than they do in noncarriers.

METHODS

We performed a retrospective cohort study of 1601 women in the International BRCA1/2 Carrier Cohort Study cohort, all of whom carried a mutation in BRCA1 or BRCA2. Information on reproductive factors was obtained from a questionnaire. At the time of interview 853 subjects were classified with breast cancer. Data were analyzed by using a weighted cohort approach. All statistical tests were two-sided.

RESULTS

There was no statistically significant difference in the risk of breast cancer between parous and nulliparous women. Among parous women, an increasing number of full-term pregnancies was associated with a statistically significant decrease in the risk of breast cancer (Ptrend = .008); risk was reduced by 14% (95% confidence interval [CI] = 6% to 22%) for each additional birth. This association was the same for carriers of mutations in either BRCA1 or BRCA2 and was restricted to women older than 40 years. In BRCA2 mutation carriers, first childbirth at later ages was associated with an increased risk of breast cancer compared with first childbirth before age 20 years (20-24 years, hazard ratio [HR] = 2.33 [95% CI = 0.93 to 5.83]; 25-29 years, HR = 2.68 [95% CI = 1.02 to 7.07]; > or = 30 years, HR = 1.97 [95% CI = 0.67 to 5.81]), whereas in BRCA1 mutation carriers, first childbirth at age 30 years or later was associated with a reduced risk of breast cancer compared with first childbirth before age 20 years (HR = 0.58 [95% CI = 0.36 to 0.94]). Neither history of interrupted pregnancies (induced abortions or miscarriage) nor history of breast-feeding was statistically significantly associated with the risk of breast cancer.

CONCLUSIONS

BRCA1 and BRCA2 mutation carriers older than 40 years show a similar reduction in breast cancer risk with increasing parity as non-carriers.

Age at menarche and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

Age at menarche is a strong and consistent predictor of breast cancer risk in the general population, but has not been well studied in women with a family history of breast cancer. We conducted this study to examine whether the presence of a deleterious BRCA1 or BRCA2 mutation influences age at menarche and to investigate whether or not there is an association between age at menarche and the risk of breast cancer in BRCA1 or BRCA2 mutation carriers. The presence of a deleterious BRCA1 or BRCA2 mutation did not appear to influence a woman's age at menarche. A matched case-control study was conducted on 1311 pairs of women who have been identified to be carriers of a deleterious mutation in either the BRCA1 (n = 945 pairs) or the BRCA2 gene (n = 366 pairs). Information about age at menarche was derived from a questionnaire routinely administered to carriers of a mutation in either gene. Among women who carried a deleterious BRCA1 mutation, age at menarche was inversely associated with the risk of breast cancer (p trend = 0.0002). This association was not observed among BRCA2 mutation carriers (p trend = 0.49). Compared with BRCA1 carriers whose age at menarche was < or =11 years, women with a menarcheal age between 14 and 15 years old had a 54% reduction in risk (OR = 0.46; 95% CI 0.30-0.69). This study implicates early age at menarche as a determinant of breast cancer among women with a BRCA1 mutation.

Younger birth cohort correlates with higher breast and ovarian cancer risk in European BRCA1 mutation carriers

Mutations in the BRCA1 gene result in an elevated risk of breast cancer (BC) and ovarian cancer (OC). However, risk estimates vary depending on the study population and statistical methodology used, and there are indications that the birth cohort and location of the mutation influence cancer risk. We investigated the risks for BC and OC associated with BRCA1 mutations in a young cohort of female mutation carriers who were identified by molecular genetic testing and belonged to a genetically heterogeneous Central European population. The study included 106 healthy and 158 affected carriers identified at an Austrian risk evaluation center. Risk estimation employed the product limit method. The log rank test was used to compare different strata. The risk of developing cancer to age 70 was found to be 85% for BC (95% CI 75-97%) and 53% for OC (95% CI 37-68%). Female mutation carriers born in 1958 or later were subject to a significantly higher risk of BC (P=0.005; 27% vs. 46% to age 40) and OC (P=0.006; 2% vs. 8% to age 40) than those born earlier. Mutations in exon 11 were associated with lower BC risk than mutations in exons 1-10 (P=0.008) and exons 12-24 (P=0.0006). OC risk was not influenced by mutation location (P=0.86). We conclude that female BRCA1 mutation carriers should be counseled about their cohort-dependent cancer risk. Further research into variables that affect cancer risk and are amenable to modification (e.g., lifestyle-related factors) should be considered a priority.

A weighted cohort approach for analysing factors modifying disease risks in carriers of high-risk susceptibility genes

The authors propose a novel approach to evaluate the effects of risk factors on disease risks in carriers of high-penetrance alleles in disease susceptibility genes. Most studies to date have utilised data collected on carriers identified through ongoing genetic testing programs. The advantage of this approach is that it allows relatively large numbers of affected and unaffected carriers to be identified rapidly. However, genetic testing is targeted at individuals with a strong family history of disease, so that the selection of carriers is not random with respect to disease status. Risk factors are often analysed by standard cohort analysis methods, but these can be biased in retrospective studies if subjects are selected on the basis of phenotype. To overcome this problem, a weighted cohort approach is proposed, under which individuals are weighted according to certain sampling probabilities in order to mimic a true cohort. The method is illustrated by analyses of data from the International BRCA1/2 Carrier Cohort Study (IBCCS). Simulations demonstrate that the method gives rate ratio estimates that are close to unbiased provided that the absolute disease risks are well estimated. The power to detect associations is, however, reduced compared with an unweighted approach.

Towards a dietary prevention of hereditary breast cancer

Inheritance of a deleterious mutation in BRCA1 or BRCA2 confers a high lifetime risk of developing breast cancer. Variation in penetrance between individuals suggests that factors other than the gene mutation itself may influence the risk of cancer in susceptible women. Several risk factors have been identified which implicate estrogen-induced growth stimulation as a probable contributor to breast cancer pre-disposition. The protein products of both of these genes appear to help preserve genomic integrity via their participation in the DNA damage response and repair pathways. To date, the evidence for a cancer-protective role of dietary nutrients, for the most part those with antioxidant properties, has been based on women without any known genetic pre-disposition and it is important to identify and evaluate dietary factors which may modify the risk of cancer in BRCA carriers. Here we propose that diet modification may modulate the risk of hereditary breast cancer by decreasing DNA damage (possibly linked to estrogen exposure) or by enhancing DNA repair. The prevention of hereditary breast cancer through diet is an attractive complement to current management strategies and deserves exploration.

Hereditary ovarian cancer

Family history is the strongest risk factor for ovarian cancer. Three clinical manifestations of hereditary ovarian cancer have been recognized: (1) "site-specific" ovarian cancer, (2) the breast and ovarian cancer syndrome, and (3) the hereditary nonpolyposis colorectal cancer (HNPCC; Lynch II) syndrome. The first 2 groups are associated with germ line mutations in the BRCA1 and BRCA2 tumor suppressor genes, whereas HNPCC is associated with germ line mutations in the DNA mismatch repair (MMR) genes, primarily hMLH1 and hMSH2. At least 10% of all epithelial ovarian cancers are hereditary, with mutations in the BRCA genes accounting for approximately 90% of cases and most of the remaining 10% attributable to HNPCC. Hereditary ovarian cancers exhibit distinct clinicopathologic features compared with sporadic cancers. The cumulative lifetime risk of ovarian cancer is 40% to 50% for BRCA1 mutation carriers and 20% to 30% for BRCA2 mutation carriers. Both BRCA proteins participate in transcriptional regulation of gene expression as well as the recognition or repair of certain forms of DNA damage, particularly double-strand breaks. Mutations of BRCA1 and BRCA2 are mainly of the frameshift or nonsense variety. Most ovarian cancers associated with germ line BRCA mutations are diagnosed at a younger age and are high-grade and advanced-stage serous carcinomas. BRCA mutations do not seem to play a significant role in the development of mucinous or borderline ovarian tumors. Hereditary ovarian cancers have a distinctly better clinical outcome with longer overall survival and recurrence-free interval after chemotherapy than sporadic cancers. Women with a family history including 2 or more first- or second-degree relatives with either ovarian cancer alone or both breast and ovarian cancers should undertake prophylactic oophorectomy immediately after childbearing has been completed to reduce the risk of ovarian cancer. The cumulative risk of ovarian cancer in HNPCC families is more than 12%. Ovarian cancer in HNPCC syndrome is diagnosed at younger age than in the general population. Most tumors are low-stage well-differentiated or moderately differentiated carcinomas. Annual follow-up is recommended for these patients.

Gene-environment interactions in human diseases

Studies of gene-environment interactions aim to describe how genetic and environmental factors jointly influence the risk of developing a human disease. Gene-environment interactions can be described by using several models, which take into account the various ways in which genetic effects can be modified by environmental exposures, the number of levels of these exposures and the model on which the genetic effects are based. Choice of study design, sample size and genotyping technology influence the analysis and interpretation of observed gene-environment interactions. Current systems for reporting epidemiological studies make it difficult to assess whether the observed interactions are reproducible, so suggestions are made for improvements in this area.

Breast cancer risk inBRCA1 andBRCA2 mutation carriers and polyglutamine repeat length in theAIB1 gene

Marked variation in phenotypic expression among BRCA1 and BRCA2 mutation carriers may be partly explained by modifier genes that influence mutation penetrance. Variation in CAG/CAA repeat lengths coding for stretches of glutamines in the C-terminus of the AIB1 protein (amplified in breast cancer 1, a steroid receptor coactivator) has been proposed to modify the breast cancer risk in women carrying germline BRCA1 mutations. We genotyped the AIB1 repeat length polymorphism from the genomic DNA of a group of 851 BRCA1 and 324 BRCA2 female germline mutation carriers to estimate an association with breast cancer risk modification. Hazard ratios (HR) were calculated using a Cox proportional hazards model. For BRCA1 and BRCA2 mutation carriers, analyzed separately and together, we found that women who carried alleles with 28 or more polyglutamine repeats had no increased risk of breast cancer compared to those who carried alleles with fewer repeats (HR for BRCA1/2 carriers = 0.88, 95% CI [confidence interval] = 0.75-1.04). Analyzing average repeat lengths as a continuous variable showed no excess risk of breast cancer (BC) in BRCA1 or BRCA2 mutation carriers (HR for average repeat length in BRCA1/2 carriers = 1.01, 95% CI = 0.92-1.11). These results strongly suggest that contrary to previous studies, there is no significant effect of AIB1 genetic variation on BC risk in BRCA1 mutation carriers and provide an indication that there is also no strong risk modification in BRCA2 carriers.

Epidemiology of breast cancer among BRCA mutation carriers: an overview

Mutations in BRCA1 and BRCA2 have been associated with an increased lifetime risk of breast and ovarian cancers. Many of the well-recognized risk factors and risk modifiers in other women appear to operate similarly in BRCA mutation carriers. However, current evidence suggests that BRCA-related breast cancer risk is positively associated with pregnancy and parity, while smoking may reduce the risk. The incidence of BRCA1-related breast cancer is high before the age of 35 years and oral contraceptive use for 5 or more years is associated with increased risk of this disease among women carrying BRCA1 mutations.

A qualitative study looking at the psychosocial implications of bilateral prophylactic mastectomy

The study objective was to explore the attitudes and beliefs of women at high risk of developing breast cancer who accepted or declined bilateral prophylactic mastectomy (BPM). This qualitative study employed semi-structured interviews of 60 women who opted for BPM and 20 women who declined. Interviews took place in the women's own homes. Qualitative analysis led to the generation of a number of categories that provided conceptualisation of the women's primary experiences. These categories included: anxiety; surgery; sexual impact; information; gene testing; reconstruction and support. The study revealed that there is a clear need for information to be written specifically for this patient group and that emotional support for high-risk women offered BPM should be provided.

Hereditary breast cancer in Jews

A family history of breast cancer poses higher risks for Jewish versus non-Jewish women, particularly for early-onset breast cancer. This appears to be due in large part to the high prevalence (2.5%) of three BRCA1 and BRCA2 founder mutations in Ashkenazi Jews. About 4 to 8% of non-Jewish male breast cancer cases versus 19% of Jewish male breast cancer cases carry germline BRCA mutations. Jewish women are disproportionately impacted by BRCA mutations throughout life, with a 10% carrier rate for breast cancer diagnosed at any age and a 21 to 30% carrier rate for breast cancer diagnosed by age 40. Comparable rates in non-Jewish populations are 6.1% for breast cancer diagnosed before age 50. Lifetime penetrance estimates based on genotyping of probands have ranged widely in Jewish and non-Jewish populations. However, a study of 1008 Jewish women with breast cancer which extended genotyping to relatives found high penetrance rates with considerably smaller standard errors. This study and studies of early-onset incident breast cancer in non-Jews have found that at least half of high-risk cases would be missed by family history screening alone. While the carrier rate in non-Jewish populations is too low to consider genetic screening, the carrier rate in Ashkenazi Jews is high and genetic screening poses fewer technical barriers. The high genetic attributable cancer risks of Ashkenazi BRCA founder mutations, the sobering lethality of ovarian and early onset breast cancers, and the increasing clarity about effectiveness of medical interventions make imperative further dialogue and research to keep guidelines for genetic screening up to date.

Hereditary ovarian cancer in Ashkenazi Jews

Ovarian cancer is the fourth leading cause of cancer deaths among American women. While women in both the Ashkenazi and non-Ashkenazi populations have an estimated 1.7% lifetime risk of acquiring malignancy, the proportion of hereditary ovarian cancer is much higher in the Ashkenazim. Most of this increased proportion of hereditary ovarian cancer risk is accounted for by inherited mutations in the BRCA1 and BRCA2 genes. In the Ashkenazi Jewish population, 29 to 41% of ovarian cancer is believed to be secondary to inheriting one of three founder mutations in BRCA 1 and BRCA 2, while only 10% of ovarian cancer is attributed to mutations of these genes in non-Ashkenazim. In the US population in general, it is estimated that between 1 out of 345 and 1 out of 1000 individuals carries a BRCA mutation, compared with approximately 1 in 40 individuals of Ashkenazi Jewish descent. The ovarian cancer risk up to age 70 associated with BRCA mutation carriers has been reported to be as high as 66% for BRCA1 and 27% for BRCA2 mutation carriers. Ovarian cancer in Ashkenazi kindreds has served as a model for the study of the histopathology of inherited ovarian cancers as well as for the study of risk reduction and screening among all women at inherited risk of ovarian cancer.

[Can breast cancer be chemoprevented in 2003?]

Breast cancer is certainly not preventable at the same degree as lung cancer is by avoiding cigarette smoking or bladder cancer by avoiding exposure to some specific professional carcinogens. Despite the increased availability of screening mammography and the use of adjuvant chemotherapy, breast cancer remains a major cause of morbidity and mortality in women. Chemoprevention could be one of the possible weapons to decrease the morbidity and the mortality due to breast cancer. Experimental, epidemiological and clinical data suggest that one can prevent occurrence of breast cancer. The results of five trials including more than 25,000 patients comparing the effectiveness of tamoxifen with a placebo were published. The results of these trials, at first sight, do not agree. Only in the USA, the results of the five trials have led to licence tamoxifen for chemoprevention of breast cancer. But the Food and Drug Administration stresses the fact that the noxious side effects are too numerous for this molecule to be prescribed with all the patients. It must be reserved for the women presenting an increased risk. The means of identifying the women at increased risk are not yet perfect.

Oral contraceptives and risk of familial breast cancer

The risk of breast cancer of oral contraceptive (OC) use in 1423 women from families with hereditary/familial breast cancer recruited through a cancer family clinic was analyzed in a matched case-control study. Ninety-eight women tested positive for a BRCA1 mutation. Hazard ratio for ever use of OCs adjusted for other risk factors was 0.90 (95% confidence interval (CI) 0.68-1.18) in the total data set and 2.00 (0.36-10.9) in BRCA1 mutation carriers. We did not find evidence for interaction between BRCA1 mutation status and OC use on breast cancer risk. Recent users had a statistically significant increase in risk with hazard ratios of 1.99, 2.05, and 1.69 for up to 5, 10, and 15 years since last OC use, while users with more than 15 years since last use had a reduction of risk to 0.69 compared to never users. We conclude that the effects of OC use on breast cancer risk in familial breast cancer may be similar to the effects in the general population. For BRCA1 mutation carriers, the point estimate is a doubling of risk, but CI is wide and no conclusion may be drawn from this study alone.

BRCA2 mutation carriers, reproductive factors and breast cancer risk

BACKGROUND

Germline mutations in the BRCA genes dramatically increase the risk of breast cancer. In the general population, breast cancer risk is affected by age at menarche, by age at first birth, by the number of births and by the duration of breast feeding. Whether this is true for mutation carriers is not clear.

METHODS

In a case-control study, nested in a population-based cohort of the Icelandic Cancer Detection Clinic, two groups of cases were defined, matched on year of birth, on age at diagnosis and on age when giving information on reproductive factors: 100 carriers of the Icelandic founder BRCA2 mutation 999del5, and 361 BRCA2-negative cases. The mean age at diagnosis was 48 years. There were 1000 women in a matched group of unaffected controls. Conditional logistic regression was used for the analysis.

RESULTS

An increased number of births was associated with a decreased risk of breast cancer in BRCA2-negative cases but not in BRCA2-positive cases. A negative association between risk and duration of breast feeding was observed only in the mutation carriers. These associations were not statistically significant, but the effects of the two variables differed significantly according to mutation status (P = 0.007 and P = 0.045 for interaction with number of births and with duration of breast feeding, respectively). This was maintained when limiting the analysis to women diagnosed older than the age of 40 years.

CONCLUSION

The association between breast cancer and the number of pregnancies and between breast cancer and the duration of breast feeding was not the same for carriers and noncarriers of a detrimental BRCA2 mutation. In the context of other epidemiological and laboratory studies, this may indicate that the product of the BRCA2 gene has a function relating to the differentiation of epithelial tissue in the breast.

Molecular aspects of ovarian cancer

Ovarian cancer is caused by genetic alterations that disrupt proliferation, apoptosis, senescence and DNA repair. Approximately 10% of ovarian cancers arise in women who have inherited mutations in cancer susceptibility genes (BRCA1 or BRCA2). The ability to perform genetic testing allows identification of women at increased risk who can be offered prophylactic oophorectomy or other interventions aimed at preventing ovarian cancer. The vast majority of ovarian cancers are sporadic, resulting from the accumulation of genetic damage over a lifetime. Several specific genes involved in ovarian carcinogenesis have been identified, including the p53 tumour suppressor gene and HER2/ neu andPIC3KA oncogenes. The recent availability of expression microarrays has facilitated the simultaneous examination of thousands of genes, and this promises to extend further our understanding of the molecular events involved in the development of ovarian cancers. Hopefully, this knowledge can be translated into effective screening, treatment, surveillance, and prevention strategies in the future.

The genetics of ovarian cancer

A family history of ovarian cancer confers an increased risk of ovarian cancer. We review the literature quantifying the familial risks associated with ovarian cancer and assess the evidence that the familial clustering of ovarian cancer is genetically determined. We then describe the known high-penetrance genes, the ovarian cancer risks attached to them and their contribution to ovarian cancer in families and in the general population. The evidence for the existence of other ovarian cancer genes is then considered.