The risk of cancer associated with specific mutations of BRCA1 and BRCA2 among Ashkenazi Jews

The prevalence of common BRCA1 and BRCA2 mutations among Ashkenazi Jews

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

Psychological impact of receiving negative BRCA1 mutation test results in Ashkenazim

PURPOSE

Most DNA test results for breast/ovarian cancer susceptibility are negative. Because negative test results might be interpreted incorrectly and may have serious psychological and behavioral implications, determining the psychological impact of such results is important.

METHODS

A community-based sample of 289 Ashkenazim was tested for 185delAG. The 199 mutation-negatives provided data at baseline and follow-up. Increased risk participants included those who received negative test results but remained at increased risk because positive family and/or personal histories of breast or ovarian cancer made the results uninformative. Average risk meant those who tested negative and had negative family and personal histories of breast or ovarian cancer. Using a logistic regression analysis, both groups' psychological distress levels were compared at baseline and at 1 and 6 months after notification of DNA test results.

RESULTS

A logistic regression analysis showed significant but small differences in cancer-specific distress after 6 months between increased and average risk participants (P < 0.006). Increased risk participants reported more distress than average risk. General distress declined among all participants after 1 month. Although baseline and follow-up differences in cancer-specific distress obtained by the increased and average risk participants were statistically significant, none of the absolute levels observed reflected especially high degrees of stress.

CONCLUSIONS

Receipt of negative DNA test results does not have a deleterious psychological impact, whether results are informative or uninformative.

Frequency of BRCA1 mutation 5382insC in German breast cancer patients

OBJECTIVE

The aim of the study was to determine the frequency of the BRCA1 mutation 5382insC in German breast cancer patients with and without prior knowledge of a family history of breast cancer.

METHODS

Two groups of breast cancer patients were tested for the presence or absence of the 5382insC mutation using a PCR primer mismatch assay. A sample of 248 patients unrelated by genealogy was selected based on a history of breast and/or ovarian cancer in the families. In addition, a population-based sample of 800 unselected breast cancer patients was included in the analysis. Three intragenic DNA markers D17S1323, D17S1322, and D17S855, located at BRCA1 introns 12, 19, and 20, respectively, were utilized for allelic association studies as well as for haplotype analysis in 4 breast/ovarian cancer families.

RESULTS

The 5382insC mutation was identified in 10/248 (4.0%) familial breast cancer patients and in 8/800 (1.0%) unselected cases. Allelic association studies and haplotype analysis revealed an association of allele Nos. "6" at D17S1323 (chi2 value = 9.34, P = 0.007), "5" at D17S1322 (chi2 value = 3.62, P = 0.171), and "4" at D17S855 (chi2 value = 11.34, P = 0. 002) with the mutation 5382insC.

CONCLUSION

5382insC constitutes a frequent BRCA1 mutation in German breast cancer patients. The significant allelic association between this mutation and two intragenic DNA markers (D17S1323, D17S855) and the elevated allele frequency at marker D17S1322 suggest an ancient founder in the German breast cancer population. The PCR primer mismatch assay described herein provides a rapid and reliable detection method for the recurrent 5382insC mutation and will be useful for the analysis of large breast cancer populations.

Centrosome amplification and a defective G2-M cell cycle checkpoint induce genetic instability in BRCA1 exon 11 isoform-deficient cells

Germline mutations of the Brca1 tumor suppressor gene predispose women to breast and ovarian cancers. To study mechanisms underlying BRCA1-related tumorigenesis, we derived mouse embryonic fibroblast cells carrying a targeted deletion of exon 11 of the Brca1 gene. We show that the mutant cells maintain an intact G1-S cell cycle checkpoint and proliferate poorly. However, a defective G2-M checkpoint in these cells is accompanied by extensive chromosomal abnormalities. Mutant fibroblasts contain multiple, functional centrosomes, which lead to unequal chromosome segregation, abnormal nuclear division, and aneuploidy. These data uncover an essential role of BRCA1 in maintaining genetic stability through the regulation of centrosome duplication and the G2-M checkpoint and provide a molecular basis for the role of BRCA1 in tumorigenesis.

An update on DNA-based BRCA1/BRCA2 genetic counseling in hereditary breast cancer

The identification of BRCA1 and BRCA2 mutations has enabled physicians to identify persons at high risk for carcinoma of the breast and ovary in hereditary breast-ovarian cancer (HBOC) families. Many physicians have limited knowledge about the effective translation of these new discoveries into clinical practice settings. This problem is further confounded by the limited number of genetic counselors who have experience with cancer genetics. Genetic counseling about DNA test results was provided to 420 patients from 37 HBC/HBOC families. Descriptive data were collected and recorded about their responses to questions posed immediately before and after test results were disclosed. Findings disclosed a significant tendency of patients to overestimate rather than underestimate their risk (P < .001) prior to receiving results. The chief reason for declining to receive results was fear of insurance discrimination. The primary reason that patients sought test results was for their children. Most women reported that, if testing identified them as mutation carriers, they would consider lifetime surveillance and prophylactic surgery. Responses to DNA test results were varied and often unpredictable. Counseling by an appropriately educated and skilled professional is essential to assist people in making decisions regarding testing and health management.

BRCA1 gene mutation and loss of heterozygosity on chromosome 17q21 in primary prostate cancer

The tumor suppressor gene BRCA1 on chromosome 17q21 has been characterized and shown to be mutated in patients with familial breast and ovarian cancer. Several studies examined the relatives of women with breast cancer and noted an association with ovarian and prostate cancer. This study investigated 24 human prostate cancer specimens for BRCA1 gene mutations and loss of heterozygosity (LOH) on chromosome 17q21 assessed by the polymerase chain reaction. LOH was identified using 7 highly polymorphic tandem repeat markers on chromosome 17q21, in addition to an analysis of the whole coding region of the BRCA1 gene. Four of the 24 prostate cancer specimens showed LOH at one or more loci, all of which were histologically poorly differentiated (4 of 11) and stage D (4 of 15). One of the 24 cases showed a germ-line mutation of the BRCA1 gene, and a sister of this patient died of ovarian cancer. It appears that the BRCA1 gene is not frequently involved in the development of primary prostate cancer.

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

BACKGROUND

Studies of survival following breast and ovarian cancers in BRCA1 and/or BRCA2 mutation carriers have yielded conflicting results. We undertook an analysis of a community-based study of Ashkenazi Jews to investigate the effect of three founder mutations in BRCA1 and BRCA2 on survival among patients with breast or ovarian cancer.

METHODS

We collected blood samples and questionnaire data from 5318 Ashkenazi Jewish volunteers. The blood samples were tested for 185delAG (two nucleotide deletion) and 5382insC (single nucleotide insertion) mutations in BRCA1 and the 6174delT (single nucleotide deletion) mutation in BRCA2. To estimate survival differences in the affected relatives according to their BRCA1 and/or BRCA2 mutation carrier status, we devised and applied a novel extension of the kin-cohort method.

RESULTS

Fifty mutation carriers reported that 58 of their first-degree relatives had been diagnosed with breast cancer and 10 with ovarian cancer; 907 noncarriers reported 979 first-degree relatives with breast cancer and 116 with ovarian cancer. Kaplan-Meier estimates of median survival after breast cancer were 16 years (95% confidence interval [CI] = 11-40) in the relatives of carriers and 18 years (95% CI = 15-22) in the relatives of noncarriers, a difference that was not statistically significant (two-sided P = .87). There was also no difference in survival times among the 126 first-degree relatives with ovarian cancer. We found no survival difference between patients with breast or ovarian cancer who were inferred carriers of BRCA1 and/or BRCA2 mutations and noncarriers.

CONCLUSIONS

Carriers of BRCA1 and BRCA2 mutations appeared to have neither better nor worse survival prognosis.

Update on breast cancer susceptibility genes

BRCA1 and BRCA2 have now been isolated and a large number of families characterized for the presence of mutations in these breast cancer susceptibility genes. Data from these studies are beginning to provide us with answers to many important questions. It is clear that estimates of attributable risk and penetrance are dependent on the population being studied. For example, studies of large, extensively affected families suggest that 45% of inherited breast cancer is due to BRCA1 mutations, while similar studies in individuals ascertained from breast cancer risk evaluation clinics suggest that the attributable risk is only 15%-20%. Similarly the large families yield penetrance estimates of 87% by age 85, while a more population-based study suggests somewhat lower rates--60% by age 70. In addition, studies of BRCA1-related tumors suggest that there may be some important molecular differences as compared to sporadic tumors, with a predominance of high grade lesions that are ER negative and an increased rate of p53 mutations. Controversy remains about the potential for genotype/phenotype correlation, and previous anecdotal reports of improved survival in families with familial breast cancer have yet to be fully evaluated. Finally, clinical recommendations are being formulated, with current recommendations centered on screening for breast cancer risk and prophylactic oophorectomy for presumed reduction of ovarian cancer risk.

The genetics of breast cancer susceptibility

Following the genomic localization and subsequent identification of the breast cancer susceptibility genes, BRCA1 and BRCA2, the basic patterns of cancer risk associated with mutations in these genes have been defined. In addition, preliminary insights into the prevalence of mutations and their contributions to cancer incidence have been acquired. Features of breast and other cancers that develop in these genetic syndromes have now been investigated and shown to differ from sporadic versions of the same neoplasms. However, several areas are complex and require further clarification. There remain discrepancies between published cancer risk estimates. Furthermore, there may be variation in cancer risk between different mutations in the same gene and there is preliminary evidence that genetic and nongenetic influences may modify risks. Finally, it is probable that the genes underlying a substantial component of susceptibility to breast cancer remain to be identified.

The genetic basis of breast cancer and its clinical implications

While it has long been recognized that a proportion of breast cancer cases are the result of an inherited familial predisposition, precise knowledge of the underlying genetic processes has been lacking. Recent advances in molecular biology, however, have shown that hereditary breast cancer may eventuate as a result of mutations on several specific gene loci including BRCA1, BRCA2, ATM gene, PTEN and p53. Several other less frequently occurring predisposition genes such as the androgen receptor gene (AR), the HNPCC genes and the oestrogen receptor gene may also be involved, but to a lesser extent. Overall, approximately 5-10% of all breast cancers are thought to involve one of these inherited predisposition genes, with BRCA1 and BRCA2 being responsible for as much as 90% of this group. Because of the complex nature of genetic testing, mutation analysis is not presently routinely available outside genetic counselling clinics. In this review the current knowledge and role of each predisposition gene is outlined and the management implications of genetic testing for members of breast cancer families for both affected and non-affected members are discussed. The need to provide comprehensive counselling for women with an inherited predisposition to breast cancer has seen the evolution of the familial cancer clinic, involving a multidisciplinary specialist team approach. Familial cancer clinics will provide individuals with information about their risk of developing breast cancer and offer advice regarding further management strategies. It is important that surgeons, who have traditionally played a key role in breast cancer treatment, remain cognizant of these advances in genetic molecular biology, and in so doing continue to remain key participants in the conduct of breast cancer management.

BRCA1 and BRCA2 gene mutations and risk of breast cancer. Public health perspectives

CONTENT

Breast cancer is the most common cancer and the second most common cause of cancer death among U.S. women. In 1998, about 178,700 new cases will be diagnosed and 43,500 women will die from the disease. Mutations in the BRCA1 gene, which was cloned in 1994 and is located on chromosome 17q, have been identified as causes of predisposition to breast, ovarian, and other cancers. A second breast cancer gene, BRCA2, has been localized to chromosome 13q. Using inferential procedures, the overall carrier frequency of BRCA1 gene mutations has been estimated at 1 in 500 in the general U.S. population. Recent studies have indicated that the carrier frequency of a specific BRCA1 allele, the 185delAG mutation, may be as high as 0.8% to 1% among women of Ashkenazi Jewish descent.

CONCLUSIONS

Due to the proliferation of laboratories offering genetic tests for breast cancer susceptibility, their appropriate use in public health needs careful scrutiny. Several issues are raised when such genetic tests are considered for population-based prevention programs for breast cancer. Public health agencies, such as the Centers for Disease Control and Prevention, are important to monitoring and evaluating genetic testing done outside of research protocols. If genetic tests for breast cancer are to be incorporated into future prevention programs, evaluation is needed of whether the testing can have the intended effect.

Benefits and costs of screening Ashkenazi Jewish women for BRCA1 and BRCA2

PURPOSE

To determine the survival benefit and cost-effectiveness of screening Ashkenazi Jewish women for three specific BRCA1/2 gene mutations.

METHODS

We used a Markov model and Monte Carlo analysis to estimate the survival benefit and cost-effectiveness of screening for three specific mutations in a population in which their prevalence is 2.5% and the associated cancer risks are 56% for breast cancer and 16% for ovarian cancer. We assumed that the sensitivity and specificity of the test were 98% and 99%, respectively, that bilateral prophylactic oophorectomy would reduce ovarian cancer risk by 45%, and that bilateral prophylactic mastectomy would reduce breast cancer risk by 90%. We used Medicare payment data for treatment costs and Surveillance, Epidemiology, and End Results data for cancer survival.

RESULTS

Our model suggests that genetic screening of this population could prolong average nondiscounted survival by 38 days (95% probability interval, 22 to 57 days) for combined surgery, 33 days (95% probability interval, 18 to 43 days) for mastectomy, 11 days (95% probability interval, 4 to 25 days) for oophorectomy, and 6 days (95% probability interval, 3 to 8 days) for surveillance. The respective cost-effectiveness ratios per life-year saved, with a discount rate of 3%, are $20,717, $29,970, $72,780, and $134,273.

CONCLUSION

In this Ashkenazi Jewish population, with a high prevalence of BRCA1/2 mutations, genetic screening may significantly increase average survival and, depending on costs and screening/treatment strategies, may be cost-effective by the standards of accepted cancer screening tests. According to our model, screening is cost-effective only if all women who test positive undergo prophylactic surgery. These estimates require confirmation through prospective observational studies and clinical trials.

Inherited colorectal polyposis and cancer risk of the APC I1307K polymorphism

Germ-line and somatic truncating mutations of the APC gene are thought to initiate colorectal tumor formation in familial adenomatous polyposis syndrome and sporadic colorectal carcinogenesis, respectively. Recently, an isoleucine-->lysine polymorphism at codon 1307 (I1307K) of the APC gene has been identified in 6%-7% of the Ashkenazi Jewish population. To assess the risk of this common APC allelic variant in colorectal carcinogenesis, we have analyzed a large cohort of unselected Ashkenazi Jewish subjects with adenomatous polyps and.or colorectal cancer, for the APC I1307K polymorphism. The APC I1307K allele was identified in 48 (10.1%) of 476 patients. Compared with the frequency in two separate population control groups, the APC I1307K allele is associated with an estimated relative risk of 1.5-1.7 for colorectal neoplasia (both P=.01). Furthermore, compared with noncarriers, APC I1307K carriers had increased numbers of adenomas and colorectal cancers per patient (P=.03), as well as a younger age at diagnosis. We conclude that the APC I1307K variant leads to increased adenoma formation and directly contributes to 3%-4% of all Ashkenazi Jewish colorectal cancer. The estimated relative risk for carriers may justify specific clinical screening for the 360,000 Americans expected to harbor this allele, and genetic testing in the setting of long-term-outcome studies may impact significantly on colorectal cancer prevention in this population.

Cancer risk in close relatives of women with early-onset breast cancer--a population-based incidence study

Inherited susceptibility to breast cancer is associated with an early onset and bilateral disease. The extent of familial risks has not, however, been fully assessed in population-based incidence studies. The purpose of the study was to quantify the risks for cancers of the breast, ovary and other sites of close relatives of women in whom breast cancer was diagnosed at an early age. Records collected between 1943 and 1990 at the Danish Cancer Registry were searched, and 2860 women were found in whom breast cancer was diagnosed before age 40. Population registers and parish records were used to identify 14 973 parents, siblings and offspring of these women. Cancer occurrence through to 31 December 1993 was determined within the Cancer Registry's files and compared with national incidence rates. Women with early-onset breast cancer were at a nearly fourfold increased risk of developing a new cancer later in life (268 observed vs. 68.9 expected). The excess risk was most evident for second cancer of the breast (181 vs. 24.5) and for ovarian cancer (20 vs. 3.3). For mothers and sisters, risks for cancers of the breast and ovary were significantly increased by two- to threefold. Bilateral breast cancer and breast-ovarian cancer were very strong predictors of familial risks, with one in four female relatives predicted to develop breast and/or ovarian cancer by age 75. Mothers had a slightly increased risk of colon cancer, but not endometrial cancer. The risk for breast cancer was also increased among fathers (standardized incidence ratio 2.5; 95% CI 0.5-7.4) and especially brothers (29; 7.7-74), although based on small numbers. The risk for prostatic cancer was unremarkable. In this large population-based survey, the first-degree relatives of women who developed breast cancer before age 40 were prone to ovarian cancer as well as male and female breast cancer, but not other tumours that may share susceptibility genes with breast cancer.

Genetic susceptibility testing and prophylactic oophorectomy

About 10% of ovarian cancer cases are thought to have a hereditary basis and family history is the strongest risk factor for the development of this disease. In the past, prophylactic oophorectomy has been advocated for women with two or more affected first-degree relatives. More recently, with the identification of the genes responsible for most hereditary ovarian cancers (BRCA1, BRCA2), oophorectomy can now be offered specifically to women who are mutation carriers. Conversely, non-carriers in these families can be reassured that their risk of ovarian cancer is not increased. The value of oophorectomy in mutation carriers has not yet been proven, however, and there are concerns that the benefit may be less than intuitively expected. First, although the lifetime risk of ovarian cancer initially was reported to be as high as 60%, more recent studies have reported risks in the range of 15-30%. A better understanding of the genetic and/or environmental basis of variable penetrance is needed to augment our ability to counsel women regarding their risk. In addition, peritoneal papillary serous carcinoma indistinguishable from ovarian cancer occurs in some women following oophorectomy. Studies that better define how often this occurs also are needed to establish more firmly the value of prophylactic oophorectomy. In view of the uncertainty regarding the efficacy of prophylactic oophorectomy, chemopreventive and early detection approaches also deserve consideration as strategies for decreasing ovarian cancer mortality in women who carry mutations in ovarian cancer susceptibility genes.

The current social, political, and medical role of genetic testing in familial breast and ovarian carcinomas

Few advances in medical science have yielded as much publicity and controversy as discoveries in genetics. Moving quickly from the bench to the bedside, genetic testing for inherited susceptibility to breast and ovarian cancer has had a significant impact on our paradigms for decisions about the treatment and prevention of disease. Assessment of cancer risk is developing into a distinct discipline, with rapidly evolving genetic technologies and models for estimating an individual's risk of cancer. Exciting developments in chemoprevention of breast cancer demonstrate the potential to offer a broader range of options for decreasing cancer risk. This article will consider recent advances in the understanding of cancer genetics, and describe the state-of-the-art in terms of management of individuals with inherited susceptibility to breast and ovarian cancer.

Prognostic implications of cancer susceptibility genes: any news?

Recent advances in our understanding of the genetic basis of several inherited predispositions to cancer have raised the possibility that there may be differences in prognosis between patients harbouring genetic susceptibilities to cancer and persons presenting with sporadic disease. The two best studied models of inherited susceptibilities to cancer will be considered, those of colorectal cancer and familial breast cancer. Familial colorectal cancer can be subdivided into essentially two groups: familial adenomatous polyposis and hereditary non-polyposis colorectal cancer. Familial breast cancer can be subdivided into three groups: those that can be accounted for by mutations in the breast cancer susceptibility gene BRCA 1, families harbouring mutations in BRCA 2 and families where neither BRCA 1 nor BRCA 2 appear to be involved. In this chapter several aspects of these inherited cancer predispositions will be discussed and compared with their equivalent sporadic disease counterparts.

BRCA1 mutations and other sequence variants in a population-based sample of Australian women with breast cancer

The frequency, in women with breast cancer, of mutations and other variants in the susceptibility gene, BRCA1, was investigated using a population-based case-control-family study. Cases were women living in Melbourne or Sydney, Australia, with histologically confirmed, first primary, invasive breast cancer, diagnosed before the age of 40 years, recorded on the state Cancer Registries. Controls were women without breast cancer, frequency-matched for age, randomly selected from electoral rolls. Full manual sequencing of the coding region of BRCA1 was conducted in a randomly stratified sample of 91 cases; 47 with, and 44 without, a family history of breast cancer in a first- or second-degree relative. All detected variants were tested in a random sample of 67 controls. Three cases with a (protein-truncating) mutation were detected. Only one case had a family history; her mother had breast cancer, but did not carry the mutation. The proportion of Australian women with breast cancer before age 40 who carry a germline mutation in BRCA1 was estimated to be 3.8% (95% CI 0.3-12.6%). Seven rare variants were also detected, but for none was there evidence of a strong effect on breast cancer susceptibility. Therefore, on a population basis, rare variants are likely to contribute little to breast cancer incidence.

Development of a knowledge scale about breast cancer and heredity (BCHK)

An 11-item questionnaire, the Breast Cancer and Heredity Knowledge Scale (BCHK), was developed to test general knowledge about breast cancer and hereditary breast cancer (HBC) among women at low to moderate risk of HBC. The BCHK measures knowledge about breast cancer incidence and prognosis, risk factors, screening, disease presentation and treatment, and HBC. Scale items were generated from focus group interviews, previously published breast cancer knowledge scales, and consultation with a multidisciplinary research team, including health professionals and women with breast cancer or a family history of breast cancer. A 27-item draft scale was tested on 36 breast clinic patients and 17 women from the general public. Results were used to develop the final 11-item scale. Development of the scale and its potential uses are discussed.

Effect of BRCA1 and BRCA2 on the association between breast cancer risk and family history

BACKGROUND

The discovery of BRCA1 and BRCA2 has led to a reassessment of the association between family history of breast/ovarian cancer and breast cancer risk after controlling for carrier status for mutations in the BRCA1 and BRCA2 genes. We examined whether family history of breast cancer remains a predictive risk factor for this disease after carrier status for BRCA1 and/or BRCA2 mutations is taken into consideration.

METHODS

The data are from 4730 case subjects with breast cancer and 4688 control subjects enrolled in the Cancer and Steroid Hormone Study. The probability of being a BRCA1 and/or BRCA2 gene carrier was calculated for each woman. Among predicted noncarriers, logistic regression was used to assess the relationship (odds ratios and 95% confidence intervals [CIs]) between case or control status and family history of breast or ovarian cancer. Estimates of age-specific breast cancer risk are presented by predicted carrier status.

RESULTS

Among predicted noncarriers, case subjects were 2.06 times (95% CI = 1.69-2.50) and 1.24 times (95% CI = 1.17-1.32) more likely to report a first-degree or second-degree family history of breast cancer, respectively, than were control subjects. Case subjects were 1.99 times (95% CI = 1.63-2.44), 1.66 times (95% CI = 1.18-2.38), and 2.23 times (95% CI = 0.21-24.65) more likely to report an affected mother, sister, or both, respectively, than were control subjects. A family history of ovarian cancer was not statistically significantly associated with breast cancer risk. Noncarriers were predicted to have a lifetime risk of 9% of developing breast cancer compared with a 63% risk for carriers.

CONCLUSIONS

Among women with a moderate family history of breast cancer, i.e., predicted noncarriers of BRCA1 and/or BRCA2 mutations, family history remains a factor in predicting breast cancer risk. In families with breast and ovarian cancers, the aggregation of these two cancers appears to be explained by BRCA1/BRCA2 mutation-carrier probability.

Epithelial ovarian cancer, infertility and induction of ovulation: possible pathogenesis and updated concepts

Numerous case-control, cohort studies, case reports and reviews have been published during the last 5 years regarding the association between infertility and induction of ovulation and epithelial ovarian cancer. Despite this amount of published material, final conclusions regarding direct linkage between these different aspects of infertility and ovarian cancer, as well as any data relating to a putative pathogenetic mechanism, cannot be drawn. In this review we summarize the available data as well as update a previous review by Shoham published in 1994. We outline some of the information that has become available from basic research which may help to direct investigators to suitable clinical research models that may eventually serve to clarify this enigma. Finally we share ideas that focus on specific high-risk cohorts.

Genotyping by mass spectrometric analysis of short DNA fragments

A method has been developed to produce small DNA fragments from PCR products for analysis of defined DNA variations by mass spectrometry. The genomic region to be analyzed is PCR-amplified with primers containing a sequence for the type IIS restriction endonuclease Bpml. Bpml digestion of the resultant PCR products yields fragments as small as seven bases, which are then analyzed by electrospray ionization mass spectrometry. The approach was validated using seven different variants within the APC tumor suppressor gene, in which a perfect correlation was obtained with DNA sequencing. Both the sense and antisense strands were analyzed independently, and several variants can be analyzed simultaneously. These results provide the basis for a generally applicable and highly accurate method that directly queries the mass of variant DNA sequences.

Medical implications of understanding complex disease traits

The application of genetic mapping to human disease gene identification has led to the definition of many linkages and a few disease genes in complex traits over the past two years. Its application has also increased to include aspects of pharmacogenetics relating to pharmacokinetics and pharmacodynamics.

Low incidence of BRCA1 mutations among Italian families with breast and ovarian cancer

Most familial breast or ovarian cancers are thought to be due to highly penetrant mutations in the predisposing genes BRCA1 and BRCA2. The cloning of these genes has opened a new era for the genetic counseling of women with a family history of breast or ovarian cancer. To estimate the incidence of detectable BRCA1 mutations and to define the eligibility criteria for genetic testing in the Italian population, a total of 53 patients belonging to 46 families clustering multiple cases of breast and/or ovarian cancer were investigated. Seven families presented with ovarian cancer only, 16 had both ovarian and breast cancers, and 23 were characterized by breast cancer only. Using a combination of protein truncation test (PTT) and single strand conformational polymorphism (SSCP) analysis followed, when necessary, by direct sequencing, we found 8 distinct mutations, 2 of these not reported before. Five frameshift and 2 nonsense mutations led to a truncated protein. One mutation was a missense substitution involving a cysteine in the zinc finger domain. One variant creating an ETS binding site in intron I was found but its role was not defined. The percentage of families carrying mutations was 17%. Among the families characterized by ovarian cancer only and by breast and ovarian cancer, the percentage of BRCA1 mutations was 57% and 12.5%, respectively. In contrast, the percentage of altered BRCA1 in families with only breast cancers was 9%. In the 46 Italian families studied, BRCA1 mutations were detected in fewer kindreds than those previously hypothesized based on linkage analysis, especially when these were characterized by breast cancers only. Our results indicate that families with a low number of cancer patients should be referred for BRCA1 genetic testing mainly when ovarian cancer is present.

Current policies for surveillance and management in women at risk of breast and ovarian cancer: a survey among 16 European family cancer clinics. European Familial Breast Cancer Collaborative Group

The recent isolation of breast cancer predisposing genes (BRCA1 and BRCA2) allows the identification of carriers within affected families. These carriers have a 50-85% risk of developing breast or ovarian cancer and need careful follow-up. The purpose of this study was to evaluate the management and screening protocols implemented in high risk families at various family cancer clinics in Europe. A questionnaire was mailed to the members of the European Familial Breast Cancer Collaborative Group (n = 30) requesting information on the following issues: indication for surveillance of breasts and ovaries, the recommended protocol, coordination of the screening examination, prophylactic surgery, the specific management of breast cancer in a mutation carrier and the use of oestrogen. 16 centres from nine countries responded. Most centres recommend surveillance of the breasts if the lifetime risk exceeds 15-20%. The surveillance protocol that is generally advised comprises monthly self breast examination, examination by a specialist every 6 months and annual mammography, all starting from an age between 25 and 35 years. Surveillance of the ovaries is recommended in BRCA1 and BRCA2-mutation carriers, in members from breast/ovarian cancer families and in some centres in 'breast cancer only' families with an early onset of breast cancer. The recommended protocol includes gynaecological examination, sonography and estimation of CA-125 at yearly intervals starting from the age 30-35 years. Prophylactic mastectomy is considered for proven mutation carriers in some centres. Most centres consider prophylactic oophorectomy in mutation carriers and some centres also consider it for members of breast/ovarian cancer families. This survey provides insight into the guidelines for surveillance and management of familial breast cancer used at various family cancer clinics in Europe; this insight may contribute to the appropriate management of these high risk women. It should be emphasised that most recommendations are based on experts' opinion rather than on any specific studies.

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

BACKGROUND

Estimates of an 80-90% risk of breast cancer for carriers of germline mutations in the BRCA1 and BRCA2 genes are based on studies of families at high risk of breast cancer. Risk estimates for a population are possible if the mutation status of a representative sample of that population can be assessed. In Iceland, one common founder BRCA2 mutation occurs in 0.6% of the population. Iceland has a population-based cancer registry and a large collection of pedigrees, and estimation of cancer risk in mutation carriers is therefore possible.

METHODS

We studied 575 breast-cancer patients, 541 women and 34 men unselected for family history of breast cancer. Data on cancer in first-degree relatives were available from the cancer registry. Risk of cancer was estimated by comparing the history of cancer in first-degree relatives of carriers and non-carriers.

FINDINGS

56 (10.4%) of the 541 women and 13 (38%) of the 34 men carried the 999del5 mutation. The estimated risk of breast cancer at age 50 for all female carriers of the 999del5 mutation was 17.0% (95% CI 9.1-25.9) and 37.2% (22.4-53.9) at age 70.

INTERPRETATION

The results of our population-based study show that the mean risk of breast cancer in carriers of mutation in BRCA2 is lower than previously suggested. Individual risk assessment will, however, have to take account of family history.

Testing for the BRCA1 and BRCA2 breast-ovarian cancer susceptibility genes: a decision analysis

OBJECTIVE

The authors developed a Markov decision model to evaluate the health implications of testing for mutations in the BRCA1 and BRCA2 breast-ovarian cancer susceptibility genes. Prophylactic measures considered included various combinations of immediate and delayed bilateral mastectomy and oophorectomy or taking no action.

METHODS

The model incorporated the likelihood of developing breast and/or ovarian cancer, survival, and quality of life. Parameter values were taken from public databases, the published literature, and a survey of cancer experts. Outcomes considered were additional life expectancy and quality-adjusted life years (QALYs). Results are reported for 30-year-old cancer-free women at various levels of hereditary risk.

RESULTS AND CONCLUSIONS

The vast majority of women will not benefit from testing because their pre-test risks are low and surgical prophylaxis is undesirable. However, women who have family histories of early breast and/or ovarian cancer may gain up to 2 QALYs by allowing genetic testing to inform their decisions.

Screening and clinical implications for BRCA1 and BRCA2 mutation carriers

In this article, we review the history of testing for mutations in breast cancer susceptibility genes and discuss the current state of testing for mutations in BRCA1 and BRCA2 in different clinical settings including at-risk individuals and cancer patients. The risk of breast cancer. other associated malignancies and prognosis in carriers of these mutations are reviewed. A final section includes discussion of current recommendations for surveillance and the need for further research to identify environmental and genetic factors which modify the risk of developing cancer in mutation carriers.

Patient regrets after bilateral prophylactic mastectomy

BACKGROUND

The discovery of a cadre of breast cancer susceptibility genes has resulted in an increase in the number of women seeking information about prophylactic breast surgery, but virtually no large-scale prospective databases exist to assist women considering prophylactic mastectomy.

METHODS

The authors constructed a National Prophylactic Mastectomy Registry comprised of a volunteer population of 817 women from 43 states who have undergone prophylactic mastectomy.

RESULTS

In the registry, 370 women had undergone bilateral prophylactic mastectomy. Twenty-one (5%) women expressed regrets about the procedure. The median follow-up was 14.6 years (mean 14.8 years; range 0.2-51 years). Those with regrets were subsetted into those with major (n = 10) or minor (n = 7) regrets. Regrets were more common in those women with whom discussion about prophylactic mastectomy was initiated by a physician (19/255), compared with patients who initiated the discussion themselves (2/108; P < .05).

CONCLUSIONS

The overall satisfaction rate of 95% reported here may be explained by the voluntary nature of this registry. The most important factor that predicts an unfavorable outcome following bilateral prophylactic mastectomy is a physician-initiated discussion.

The genetics of inherited breast cancer

The isolation of BRCA1 and BRCA2 has greatly increased our understanding of the genetics of inherited breast and ovarian cancer although the functions of these genes are not yet fully understood. We will discuss the current state of knowledge about the function of BRCA1 and BRCA2 and summarize the cancer risks in women carrying a BRCA1 or BRCA2 mutation. We review the evidence for gene-gene and gene-environment interaction in modifying that risk, and discuss the contribution of BRCA1 and BRCA2 and other high penetrance genes to both inherited and sporadic breast cancer.