Germ-line BRCA1 mutations in Jewish and non-Jewish women with early-onset breast cancer

Novel indications for BRCA1 screening using individual clinical and morphological features

Since there is a lack of common family profile among BRCA1-gene carriers, and since the risk of being a mutation carrier is not limited to women with a family history of breast or ovarian cancer, multivariate statistical analysis using the logistic-regression model was carried out, to discriminate between sporadic cases and BRCA1-breast cancers (BRCA1-BCs), especially when information about the family history of breast/ovarian cancer and ethnicity are irrelevant or unavailable, in order to offer specific medical treatment to this population. We examined 32 BRCA1-BCs selected at cancer genetic clinics and 200 consecutive controls without family history of breast cancer for age at onset and current morphological parameters. Following the multivariate analysis, 3 parameters only, namely, early age at cancer onset [odds ratio (OR) for each year = 1.16; p < 0.0001], estrogen-receptor negativity (OR = 5.7; p = 0.01) and poor differentiation (OR = 5; p = 0.03) were found significant factors for predicting BRCA1-carrier status. The expected impact in BRCA1 screening of our model was estimated using data on 5700 breast-cancer cases from a hospital-based registry. Only 50 and 15% of tumours with early age at onset below 35 years present one or the other 2 discriminant parameters respectively. Consequently, whereas the probability of finding a BRCA1 mutation is rated low (6.2%) when the sole criterion of early onset up to the age of 35 years is used, based on our model, in the sub-group of women with a tumor that is both estrogen-receptor-negative and poorly differentiated the mutation-detection rate is predicted to be above the 10% chance level recommended by the ASCO guidelines. This sub-group of women, representing about 1% of all breast-cancer cases in Western countries, consequently deserves to be tested.

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

BACKGROUND

Mutations in the BRCA1 and BRCA2 genes are found in most families with cases of both breast and ovarian cancer or with many cases of early-onset breast cancer. However, in an outbred population, the prevalence of BRCA1 and BRCA2 mutations in patients with breast cancer who were unselected for a family history of this disease has not been determined.

METHODS

Mutations in the BRCA1 and BRCA2 genes were detected in blood samples from two population-based series of young patients with breast cancer from Britain.

RESULTS

Mutations were detected in 15 (5.9%) of 254 women diagnosed with breast cancer before age 36 years (nine [3.5%] in BRCA1 and six [2.4%] in BRCA2) and in 15 (4.1%) of 363 women diagnosed from ages 36 through 45 years (seven [1.9%] in BRCA1 and eight [2.2%] in BRCA2). Eleven percent (six of 55) of patients with a first-degree relative who developed ovarian cancer or breast cancer by age 60 years were mutation carriers, compared with 45% (five of 11) of patients with two or more affected first- or second-degree relatives. The standardized incidence ratio for breast cancer in mothers and sisters was 365 (five observed and 1.37 expected) for 30 mutation carriers and 199 (64 observed and 32.13 expected) for 587 noncarriers. If we assume recent penetrance estimates, the respective proportions of BRCA1 and BRCA2 mutation carriers are 3.1% and 3.0%, respectively, of patients with breast cancer who are younger than age 50 years, 0.49% and 0.84% of patients with breast cancer who are age 50 years or older, and 0.11% and 0.12% of women in the general population.

CONCLUSIONS

Mutations in the BRCA1 and BRCA2 genes make approximately equal contributions to early-onset breast cancer in Britain and account for a small proportion of the familial risk of breast cancer.

Breast disease in adolescents and young women

Breast lesions, including mastalgia; benign proliferative changes; and benign masses, including fibroadenomas, are common in adolescents and young adult women. Breast cancer is rare in women less than 20 years old and uncommon in women less than 30 years old. Discrete masses in women less than 30 years old that do not feel suspicious on examination can be observed for 1 or 2 months. If they persist, than an FNA can differentiate those that are benign and can be observed versus those that need either an excisional biopsy or definitive surgery. Mammography has little role in the diagnosis of women less than 30 years old except in those individuals with highly suspicious lesions on examination.

Molecular prognostic markers in breast cancer

Based on the scientific literature, there are several molecular markers which might be used for the prognosis of breast cancer. Possible molecular prognostic markers are: BRCA-1, BRCA-2, p53, erbB oncogenes, loss of heterozygosity (LOH), chromosomal aberrations, microsatellite instability, transforming growth factor alpha (TGFalpha), and the multiple drug resistance (MDR) gene. In this chapter, we discuss the possible role of these prognostic markers in breast cancer.

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.

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.

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.

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.

Founder BRCA1 and BRCA2 mutations in French Canadian breast and ovarian cancer families

We have identified four mutations in each of the breast cancer-susceptibility genes, BRCA1 and BRCA2, in French Canadian breast cancer and breast/ovarian cancer families from Quebec. To identify founder effects, we examined independently ascertained French Canadian cancer families for the distribution of these eight mutations. Mutations were found in 41 of 97 families. Six of eight mutations were observed at least twice. The BRCA1 C4446T mutation was the most common mutation found, followed by the BRCA2 8765delAG mutation. Together, these mutations were found in 28 of 41 families identified to have a mutation. The odds of detection of any of the four BRCA1 mutations was 18.7x greater if one or more cases of ovarian cancer were also present in the family. The odds of detection of any of the four BRCA2 mutations was 5.3x greater if there were at least five cases of breast cancer in the family. Interestingly, the presence of a breast cancer case <36 years of age was strongly predictive of the presence of any of the eight mutations screened. Carriers of the same mutation, from different families, shared similar haplotypes, indicating that the mutant alleles were likely to be identical by descent for a mutation in the founder population. The identification of common BRCA1 and BRCA2 mutations will facilitate carrier detection in French Canadian breast cancer and breast/ovarian cancer families.

Mutations in BRCA1 from fixed, paraffin-embedded tissue can be artifacts of preservation

DNA isolated from paraffin-embedded tissues has been used for analysis of DNA alterations in disease states. Use of archival tissue can expedite the gathering of large numbers of specimens from rare disease subtypes that would take years to accumulate prospectively. Therefore, archival tissues from 70 ovarian cancer cases diagnosed before or at age 40 were retrieved for analysis of BRCA1 mutations. DNA was isolated from paraffin-embedded tissue of 70 ovarian cancer cases diagnosed before or at age 40. BRCA1 mutation analysis was conducted by single-strand conformation polymorphism analysis and DNA sequencing. Fifty-eight BRCA1 mutations were found in 34 of the 70 ovarian cancer cases. Twenty-two cases had one mutation each and 12 cases had multiple mutations. Multiple mutations found in histologically normal tissue of 2 cases were not present in matched tumor tissue. For another case, DNA from two separate blocks of normal tissue contained different mutations. These observations were anomalous and suggested that mutations detected in fixed tissues may be artifacts of tissue preservation and not present in the original unfixed tissues. To test this suggestion, blood was obtained from 2 patients for whom mutations were found in fixed, normal tissue. DNA from their unfixed lymphocytes did not contain the mutations found in fixed normal tissue. Thus, mutations found in fixed, paraffin-embedded tissues can be artifacts of tissue preservation. The reliability of DNA sequence data derived from such tissues must be questioned in the absence of corroborating data from unfixed tissues. This severely limits the use of fixed tissues as a source of DNA for retrospective research and for clinical genetic testing in families for which a disease-affected member is not alive.

Pathobiologic characteristics of hereditary breast cancer

Patients with hereditary breast cancer (HBC) present at a young age with breast cancers that show adverse pathological characteristics such as high nuclear grade, negative hormone receptor status, and high proliferation indices. Surprisingly, the clinical course has been reported to be comparable or improved compared with patients with nonhereditary breast cancer (non-HBC). To determine whether there are any molecular markers that might help explain this paradox between pathologically aggressive neoplasms in patients with HBC and the lack of extreme clinically aggressive disease, we studied several molecular parameters in a group of 34 breast cancer patients with mutations in either the BRCA1 or BRCA2 tumor suppressor genes and compared them with a group of 20 breast cancer patients with non-HBC. In general, patients with HBC had tumors that were of higher nuclear grade, contained a higher population of proliferating cells, showed increased expression of DNA topoisomerase II-alpha (topo II-alpha), lacked hormone receptors, and were more likely to show immunopositivity for the p53 tumor suppressor gene. Additionally, tumors from patients with HBC showed a decreased angiogenesis compared with controls. The decreased angiogenesis and the elevated expression of topo II-alpha (an anticancer drug target) may, in part, explain the lack of correlation between clinical course and histological characteristics in patients with HBC.

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.

Absence of 185delAG mutation of the BRCA1 gene and 6174delT mutation of the BRCA2 gene in Ashkenazi Jewish men with prostate cancer

Epidemiological studies have demonstrated a clustering of breast and prostate cancers in some families. Moreover, there is an increase in the number of cases of prostate cancer in families with inherited mutations of the breast cancer susceptibility gene BRCA1. We assessed the role of BRCA1 and BRCA2 in prostate cancer. We tested for the BRCA1 185delAG frameshift mutation, found in 0.9% of Ashkenazi Jews, and the BRCA2 6174delT mutation, found in 1% of Ashkenazi Jews, in Ashkenazi Jewish men with prostate cancer. We studied 60 Ashkenazi men with prostate cancer. A family history was obtained by interview or a self-report questionnaire. Histological confirmation of diagnosis was obtained for all subjects. Ethnic background was confirmed for all subjects by self-report or interview. Mutations of BRCA1 and BRCA2 were detected by amplification of lymphocyte DNA from peripheral blood according to standard polymerase chain reaction (PCR) and dot blot procedures. Patients' ages ranged from 55 to 80 years (mean +/- s.d. 70 +/- 5.25). There were six men with a family history of prostate cancer; three of these had a father with prostate cancer. Five of the men had a family history of breast cancer, in a mother, a sister or an aunt. None of the men had a family history of both breast and prostate cancer. None of the 60 men carried the 185delAG BRCA1 or 6174delT BRCA2 mutations. Of 268 Ashkenazi Jewish women with sporadic breast cancer, tested in an unrelated study, 16 carried either the 185delAG mutation of BRCA1 or the 6174delT mutation of BRCA2. There was a significant difference in the incidence of the BRCA1 and BRCA2 mutations in the breast and prostate cancer cases (P = 0.05, two-tailed Fisher's exact test). The contribution of germline BRCA1 and BRCA2 mutations to prostate cancer incidence is probably small and could be limited to specific subgroups.

A family with three germline mutations in BRCA1 and BRCA2

Several cancer genetics centres offer testing for specific BRCA1 and BRCA2 mutations to Ashkenazi Jewish individuals with a family history of breast and ovarian cancers. Testing involves screening for three common mutations found in this population, namely BRCA1 185delAG, 5382insC and BRCA2 6174delT (Struewing et al., Nat Genet 1995: 11: 198-200; Roa et al., Nat Genet 1996: 14: 185-187; Oddoux et al., Nat Genet 1996: 14: 188-190). We have identified a large Ashkenazi Jewish kindred (W9170) with ten cases of breast cancer and four cases of ovarian carcinoma. Initially, mutation analysis for this family identified a BRCA1 185delAG mutation in the proband diagnosed with three separate primary cancers of the breast, ovary and colon. Another individual in this family diagnosed with two primary cancers of the ovary and breast, was identified as having a second mutation, BRCA1 5382insC. Subsequent work found that two sisters (cousins of the proband), both diagnosed with carcinoma of the breast, had a third mutation, BRCA2 6174delT. These three mutations have previously been found to be more common in the Ashkenazi Jewish population (References as above). The identification of all three mutations in one family, raised new implications for the manner in which testing and counselling should be offered. In our opinion, Ashkenazi Jewish individuals in breast-ovarian cancer families should be offered complete testing for the three common Ashkenazi Jewish mutations regardless of previous identification of one of these mutations in the family.

An important role for BRCA1 in breast cancer progression is indicated by its loss in a large proportion of non-familial breast cancers

The presence of BRCA1 protein was determined immunohistochemically in normal and benign breast biopsies, non-familial breast carcinomas and breast carcinomas from one or more individuals from 8 BRCA1 families. Strikingly, little staining was detected in breast carcinomas from BRCA1 families, regardless of the position or type of mutation, whereas strong immunostaining was observed in 28/28 of non-malignant breast biopsies. Furthermore, BRCA1 staining was reduced in non-familial breast carcinomas, since loss of nuclear BRCA1 staining was evident in 19% of non-familial breast carcinomas whilst a similar proportion (20%) showed absence of either cytoplasmic or nuclear BRCA1 staining. Statistical analysis indicates that breast cancer is characterised by a reduction in levels of nuclear BRCA1 in familial (p < 0.001) and non-familial breast cancer (p = 0.001). In non-familial breast cancer absence of nuclear BRCA1, but not cytoplasmic BRCA1, is more common in high grade breast carcinomas (p = 0.03) and in patients with evidence of lymph node involvement (p = 0.05). Correlation between the absence of BRCA1 protein with high grade is consistent with previous findings of a correlation between mutations in the BRCA1 gene and high grade. Our findings provide new evidence in support of BRCA1 as a tumour suppressor protein in non-familial breast cancer.

Use of oral contraceptives and risk of breast cancer in young women

Many studies have shown that oral contraceptive (OC) use increases a young woman's risk of breast cancer, although some studies suggest that the risk may be limited to recent use. The objective of this study was to determine what particular aspects of OC use could be important for breast cancer development at an early age in the cohort of women who had the opportunity to use OCs all of their reproductive life. The cases were first diagnosed with breast cancer at age 40 or younger between 1983 and 1988, and identified by the Los Angeles County Cancer Surveillance Program. Control subjects were individually matched to participating cases on birth date (within 36 months), race (white), parity (nulliparous versus parous), and neighborhood of residence. Detailed OC histories were obtained during in-person interviews with subjects. In general the risk estimates were small, and not statistically significant. Compared to no use, having used OCs for 12 years or more was associated with a modest non-significant elevated breast cancer risk with an odds ratio (OR) of 1.4 (95% confidence interval (CI) = 0.8-2.4). Long-term (12 years or more) users of high-dose estrogen pills had a non-significant 60% higher breast cancer risk than never users (CI = 0.9-3.2). Early use was associated with slightly higher ORs among young women (age < or =35), and among parous women. Recent use was associated with somewhat higher ORs among parous women and women above age 36. Analyses by stage, body weight, and family history yielded similar results. This study is consistent with a modest effect of early OC use on breast cancer risk in young women.

Frequency and carrier risk associated with common BRCA1 and BRCA2 mutations in Ashkenazi Jewish breast cancer patients

Based on breast cancer families with multiple and/or early-onset cases, estimates of the lifetime risk of breast cancer in carriers of BRCA1 or BRCA2 mutations may be as high as 85%. The risk for individuals not selected for family history or other risk factors is uncertain. We determined the frequency of the common BRCA1 (185delAG and 5382insC) and BRCA2 (6174delT) mutations in a series of 268 anonymous Ashkenazi Jewish women with breast cancer, regardless of family history or age at onset. DNA was analyzed for the three mutations by allele-specific oligonucleotide hybridization. Eight patients (3.0%, 95% confidence interval [CI] 1.5%-5.8%) were heterozygous for the 185delAG mutation, two (0.75%, 95% CI 0.20-2.7) for the 5382insC mutation, and eight (3.0%, 95% CI 1.5-5.8) for the 6174delT mutation. The lifetime risk for breast cancer in Ashkenazi Jewish carriers of the BRCA1 185delAG or BRCA2 6174delT mutations was calculated to be 36%, approximately three times the overall risk for the general population (relative risk 2.9, 95% CI 1.5-5.8). For the 5382insC mutation, because of the low number of carriers found, further studies are necessary. The results differ markedly from previous estimates based on high-risk breast cancer families and are consistent with lower estimates derived from a recent population-based study in the Baltimore area. Thus, presymptomatic screening and counseling for these common mutations in Ashkenazi Jewish women not selected for family history of breast cancer should be reconsidered until the risk associated with these mutations is firmly established, especially since early diagnostic and preventive-treatment modalities are limited.

Response to radiation therapy and prognosis in breast cancer patients with BRCA1 and BRCA2 mutations

BACKGROUND AND PURPOSE

The purpose of this study is to evaluate overall survival in BRCA1 or BRCA2 breast cancer patients, describe presenting stage, review histologic findings and evaluate response to radiotherapy.

MATERIALS AND METHODS

A retrospective study was performed evaluating breast cancer patients with known mutations of BRCA1 or BRCA2. Patients from 12 different pedigrees were cross-referenced with the Utah Cancer Registry (UCR), histologic findings were verified and radiotherapy records were reviewed for acute response to treatment. Actuarial survival calculations were performed and patients were matched for age, date of diagnosis and tumor size.

RESULTS

Thirty breast cancer patients with BRCA1 mutations were found to have 34 breast cancers (four had bilateral metachronous lesions) and 20 breast cancer patients with BRCA2 mutations were found to have 22 breast cancers (two had bilateral metachronous disease). The median age at diagnosis was 49 years (range 21-77 years) and 42 years (range 23-83 years), respectively, for BRCA1 and BRCA2 patients. Unusual histologic types of breast cancers were represented with 7% (4/56) medullary and 5% (3/56) lobular carcinomas. Complete staging was possible for 63% (35/56) of cancers. Stages I, II, III and IV represented 26, 63, 6 and 6% of cancers, respectively. The most severe radiation reaction was moist desquamation which was self-limiting and developed in 29% (6/21) of irradiated patients. The mean follow-up was 9.8 and 7.5 years for BRCA1 and BRCA2 cancers, respectively. Kaplan-Meier survival analysis demonstrated 5-year survival values of 75% for BRCA1 patients, 73% for BRCA2 patients, 70% for matched controls and 69% for UCR controls. No statistically significant differences were evident between the groups at 5 or 10 years.

CONCLUSIONS

Despite their younger age at presentation, breast cancer patients harboring BRCAI or BRCA2 mutations present at a similar stage, display a normal acute reaction to radiotherapy and have a similar prognosis when compared with sporadic breast cancer patients.

Breast cancer susceptibility genes. BRCA1 and BRCA2

Mutations in the BRCA1 and BRCA2 genes lead to an increased susceptibility to breast, ovarian, and other cancers. It is estimated that 3%-8% of all women with breast cancer will be found to carry a mutation in 1 of these genes. Families with multiple affected first-degree relatives and patients with early-onset disease have been found to harbor mutations at a higher frequency. The BRCA1 and BRCA2 genes code for large proteins that bear no resemblance to other known genes. In the cell, they appear to act as tumor suppressor genes and play a role in the maintenance of genome integrity, although the precise function of these genes has yet to be discovered. A large number of distinct mutations have been found in cancer families around the world. The majority of the defined pathologic mutations result in premature truncation of the protein (frameshift and nonsense mutations). These mutations may substantially increase the risk for breast and ovarian cancer, but a precise risk estimate for each different mutation cannot be determined. Depending on the familial context, the risk of breast cancer associated with carrying a mutation has been estimated to range from 50% to 85%. The role of these genes in sporadic cancer remains unknown. Patients and physicians considering BRCA1 and BRCA2 genetic testing are faced with a difficult decision. The diversity of mutations and lack of general population data prevent accurate risk prediction. This is further complicated by the paucity of data on effective prevention strategies for those identified at higher risk. Thus, the nature of clinical testing for BRCA1 and BRCA2 continues to present challenges that reinforce the necessity of personal choice within the context of thorough genetic counseling.

Breast cancer genes and the surgeon

Two genes, called BRCA-1 and BRCA-2, have been identified that appear to be responsible for the majority of familial breast cancer syndromes. These genes now play a prominent role in the practice of the surgeon treating breast cancer. Additional genes, PTEN (Cowden disease), MSH1 or MLH2 (HNPCC), and p53 (Li-Fraumeni syndrome) are responsible for other breast cancer syndromes but have not yet entered the clinical arena on a large scale. The risk of breast and ovarian cancer by age 70 in a BRCA-1 mutation carrier is estimated at 55-75% and 16-26 %, respectively, overall, and as high as 87% and 44% in those with a strong family history. The cancer risks associated with BRCA-2 mutations appear to be somewhat lower than those of BRCA-1. BRCA mutations show a strong founder effect. This is best recognized in the Ashkenazi Jewish community, in which the incidence of one of three characteristic mutations is about 2%. In other ethnic groups the pattern of mutations is different, with over 100 distinct mutations throughout the genes having been described. Most mutations so far have been frame-shift or mis-sense mutations, although large deletions have also been described. Thus, in most situations, assessment of the whole coding sequence is required to confirm or exclude a mutation. Guidelines to suggest who is likely to be a mutation carrier are being clarified, but the appropriate management of someone who tests positive remains difficult. Prophylactic mastectomy and oophorectomy are likely to offer substantial gains in life expectancy to mutation carriers, especially for young women with a strong family history. Unfortunately, there are no currently available strategies to eliminate the risk of breast or ovarian cancer. The psychological impact of testing also remains poorly understood, and the danger of various forms of discrimination remain. These factors must be clearly understood by all parties prior to testing. The process of a dynamic, interactive informed consent--much more than a simple printed document--and also counseling are central to the testing process.

Hereditary breast cancer

Genetic predisposition is responsible for 5-10% of all breast cancer, and a much larger percent of early-onset disease. Within the past few years, a number of genes associated with a high risk of breast cancer have been identified, including BRCA1, BRCA2, p53, and the Cowden disease gene PTEN/MMAC1. These genes appear to function as tumor suppressors, and although their mutation frequency in the general population is low, certain populations have a carrier frequency of up to 1% for particular BRCA1 and BRCA2 mutations. The isolation of these genes is likely to provide important insight into the pathogenesis of human cancer. The clinical application of these molecular discoveries raises controversial issues regarding presymptomatic testing for patients suspected of harboring cancer predisposing mutations.

Extra-tumoral breast tissue in breast-cancer patients: variations with a family history of breast cancer. WHO Collaborative Study of Neoplasia and Steroid Contraceptives

In order to study the relationship between benign breast changes, a family history of breast cancer and breast cancer, extratumoral breast tissue from 1259 breast-cancer patients in the WHO Collaborative Study of Neoplasia and Contraceptives was classified histologically. The occurrence of ductal hyperplasia, ductal atypia, sclerosing adenosis, adenosis, lobular atypia, lactational metaplasia, cysts, apocrine metaplasia, apocrine hyperplasia and atypia, duct ectasia and the epithelial-stromal ratio was evaluated as absent, mild, moderate or marked, along with registration of the quality and number of slides. Information on occurrence of cancer in the family was available for patients' mothers and grandmothers. Logistic-regression analyses showed that the prevalence odds ratios for lactational metaplasia, cysts, duct ectasia and calcification were significantly increased in patients with a family history of breast cancer. Apocrine metaplasia and hyperplasia were not significantly increased. The prevalence rates of ductal atypia (ductal carcinoma in situ and atypical ductal hyperplasia), ductal hyperplasia, sclerosing adenosis, adenosis and high epithelial-stromal ratio did not differ significantly among patients with or without a family history of breast cancer. A family history of other types of cancer did not influence the occurrence of any of the benign components. The findings in the present study are strikingly similar to those in our earlier comparison of extra-tumoral breast tissue in patients from countries with high and low risk of breast cancer. It is reasonable to conclude from this that a history of breast cancer in a woman's mother or grandmother and the factors leading to higher risk of breast cancer in some countries than in others have similar effects on the morphologic evolution of breast cancer through benign and pre-cancerous changes.

BRCA1 and BRCA2 mutation analysis in 86 early onset breast/ovarian cancer patients

Eighty-six women fulfilling specific selection criteria were studied for germline mutations in two breast cancer susceptibility genes, BRCA1 and BRCA2, using the protein truncation test (PTT). Nine germline mutations were identified, six in BRCA1 and three in BRCA2. Of the six BRCA1 mutations, three have previously been described and three are new, and for BRCA2, one is a new mutation and the other two appear to occur at a site that has been described several times. Four kindreds were breast cancer families, one a breast/ovarian cancer family, and the sixth an ovarian cancer family. The three kindreds with BRCA2 mutations were classified as one breast/ovarian cancer family, one breast cancer family, and one family which harboured one early onset breast cancer patient and two melanoma patients. The mutations in BRCA1 were either insertions, deletions, or transitions which all resulted in a premature stop codon. Mutations in BRCA2 were all frameshift mutations as a result of either 2 or 4 bp deletions. Two BRCA2 mutations were identical, suggesting a Swiss founder effect which was confirmed by haplotype sharing. The 10% mutation detection rate is compatible with the relaxed criteria used for patient selection. Considering the relative ease with which coding sequences can be screened by PTT, this assay is useful as a first screen for BRCA1 and BRCA2 mutations.

Cytogenetic evaluation of 20 primary breast carcinomas

Chromosome analysis was performed on samples from 20 Brazilian patients with breast cancer. All the samples were from untreated patients who presented the clinical symptoms for months or years before surgical intervention. Six cases showed axillary lymph node metastases. Clonal chromosome abnormalities were detected in all cases. The numerical alterations most frequently observed involved the loss of chromosomes X, 19, 20, and 22 followed by gain of chromosomes 9 and 8. Among the structural anomalies observed, there was preferential involvement of chromosomes 11, 6, 1, 7, 3, and 12, supporting previous reports that these chromosomes may harbour genes of importance in the development of breast tumors. Two cases with a family history of breast cancer had in common total or partial trisomy 1.

Environment and cancer: who are susceptible?

Acting in concert with individual susceptibility, environmental factors such as smoking, diet, and pollutants play a role in most human cancer. However, new molecular evidence indicates that specific groups-characterized by predisposing genetic traits or ethnicity, the very young, and women-may have heightened risk from certain exposures. This is illustrated by molecular epidemiologic studies of environmental carcinogens such as polycyclic aromatic hydrocarbons and aromatic amines. Individual genetic screening for rare high-risk traits or for more common, low-penetrant susceptibility genes is problematic and not routinely recommended. However, knowledge of the full spectrum of both genetic and acquired susceptibility in the population will be instrumental in developing health and regulatory policies that increase protection of the more susceptible groups from risks of environmental carcinogens. This will necessitate revision of current risk assessment methodologies to explicitly account for individual variation in susceptibility to environmental carcinogens.

High frequency of BRCA1 and BRCA2 germline mutations in Ashkenazi Jewish ovarian cancer patients, regardless of family history

To better understand the role of germline BRCA mutations in ovarian cancer in Ashkenazi Jews, we tested 29 consecutive patients admitted to our service for the three mutations common in this ethnic group. These mutations are 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2. Six patients had both breast and ovarian cancer, and 23 had ovarian cancer only. In the first group, all women had germline mutations, 2 with each mutation. Of 23 ovarian cancer patients, 11 were carriers (48%): 6 of 185delAG, 2 of 5382insC, and 3 of 6174delT. Regarding family history, of 13 women with no family history, 3 (23%) were carriers. Of 10 women with any family history of breast or ovarian cancer, 8 (80%) were carriers. We discuss possible explanations for this surprisingly high carrier rate, including a high proportion of familial disease coupled with lack of adequate family history, lower penetrance than previously expected, or increasing penetrance in recent generations due to nongenetic factors. Our data suggest that genetic testing is merited in all Ashkenazi women with ovarian cancer, regardless of family history.