Pharmacokinetic interaction study between eslicarbazepine acetate and lamotrigine in healthy subjects.

OBJECTIVE: Anti-epileptic drugs are often used in combination. Both eslicarbazepine (main metabolite of eslicarbazepine acetate, ESL) and lamotrigine undergo conjugation with glucuronic acid, and both eslicarbazepine and its glucuronide and lamotrigine glucuronide undergo extensive renal elimination; therefore, there is a potential for interaction. This study investigated the interaction between ESL and lamotrigine in healthy subjects. METHODS: Open-label study in two parallel groups of 16 healthy volunteers each. After an 8-day treatment with ESL or lamotrigine, ESL (1200 mg once-daily) and lamotrigine (150 mg once-daily) were co-administered for 19 days. Geometric mean ratios (GMR) and 90% confidence intervals (90% CI) for maximum plasma concentration (C(max)) and area under the plasma concentration-time curve in the dosing interval (AUC(0-24)) were calculated for eslicarbazepine (ESL active metabolite) and lamotrigine. RESULTS: The C(max) and AUC(0-24) GMR (90% CI) were, respectively, 95% (87-102%) and 96% (91-102%) for eslicarbazepine, and 88% (82-94%) and 86% (81-92%) for lamotrigine. The 90% CI of the C(max) and AUC(0-24) GMR fell within the prespecified acceptance interval (80-125%) both for eslicarbazepine and lamotrigine. CONCLUSION: There was no significant pharmacokinetic interaction between ESL and lamotrigine in healthy subjects. Therefore, no dosage adjustment appears to be usually required in either lamotrigine or ESL when the drugs are co-administered.

Prevalence and penetrance of BRCA1 and BRCA2 gene mutations in unselected Ashkenazi Jewish women with breast cancer.

BACKGROUND: Approximately 2.0%-2.5% of Ashkenazi Jewish women carry one of three founding mutations in the BRCA1 and BRCA2 genes, and each mutation is associated with a high lifetime risk of invasive breast cancer. We investigated the extent to which these three mutations contribute to breast cancer incidence in the Ashkenazi Jewish population. METHODS: We ascertained 457 Jewish women with prevalent cases of breast cancer who were unselected for age or family history of the disease; 412 of these women were tested for the three founder mutations (case patients). Control subjects consisted of 360 non-Jewish women with breast cancer (control patients) and 380 healthy Jewish women with no history of cancer (control subjects). RESULTS: Mutations were found in 48 (11.7%) of 412 Jewish case patients. Forty-six of 48 mutations occurred in women with early-onset breast cancer (<50 years) or a history of ovarian or early-onset breast cancer in a first-, second-, or third-degree relative. The estimated penetrance to age 70 years for breast cancer was 59.9% for the BRCA1 gene mutations and 28.3% for the BRCA2 gene mutation. Compared with Jewish control subjects, the relative risk (RR) of breast cancer for first-degree relatives of mutation carriers was 5.16 (95% confidence interval [CI] = 3.14-8. 48), but risk was also increased for relatives of noncarriers (RR = 1.66; 95% CI = 1.18-2.33). The RR of prostate cancer for first-degree relatives of Jewish case patients was 3.36 (95% CI = 1. 49-7.56). CONCLUSIONS: Approximately 12% of breast cancers in the Ashkenazi Jewish population are attributable to mutations in the BRCA1 or BRCA2 gene. Genetic testing may be useful when Jewish women with breast cancer are diagnosed before age 50 years or have a close relative with ovarian or early-onset breast cancer. An association between breast and prostate cancers was observed in our study population.

Effect of smoking on breast cancer in carriers of mutant BRCA1 or BRCA2 genes.

BACKGROUND: Smoking has carcinogenic effects, and possibly antiestrogenic effects as well, but it has not been found to be a risk factor for breast cancer in women in the general population. However, hereditary breast cancer is primarily a disease of premenopausal women, and interactions between genes and hormonal and environmental risk factors may be particularly important in this subgroup. METHODS: We conducted a matched case-control study of breast cancer among women who have been identified to be carriers of a deleterious mutation in either the BRCA1 or the BRCA2 gene. These women were assessed for genetic risk at one of several genetic counseling programs for cancer in North America. Information about lifetime smoking history was derived from a questionnaire routinely administered to women who were found to carry a mutation in either gene. Smoking histories of case subjects with breast cancer and age-matched healthy control subjects were compared. Odds ratios for developing breast cancer were determined for smokers versus nonsmokers by use of conditional logistic regression for matched sets after adjustment for other known risk factors. RESULTS: Subjects with BRCA1 or BRCA2 gene mutations and breast cancer were significantly more likely to have been nonsmokers than were subjects with mutations and without breast cancer (two-sided P = .007). In a multivariate analysis, subjects with BRCA1 or BRCA2 mutations who had smoked cigarettes for more than 4 pack-years (i.e., number of packs per day multiplied by the number of years of smoking) were found to have a lower breast cancer risk (odds ratio = 0.46, 95% confidence interval = 0.27-0.80; two-sided P = .006) than subjects with mutations who never smoked. CONCLUSIONS: This study raises the possibility that smoking reduces the risk of breast cancer in carriers of BRCA1 or BRCA2 gene mutations.

No association of the I1307K APC allele with ovarian cancer risk in Ashkenazi Jews.

Familial adenomatous polyposis is a dominantly inherited colon cancer syndrome associated with germ-line mutations in the APC tumor suppressor gene. An APC gene sequence alteration, the I1307K allele, occurs in 6% of the Ashkenazi Jewish population and is reported to double the risk for colorectal cancer. We screened a population of 190 Ashkenazi women who were diagnosed with epithelial ovarian carcinoma for the I1307K variant and measured the effect of this allele on the risk for cancer development in their first-degree relatives. We identified the I1307K allele in 7.9% (15 of 190) of our ovarian cancer cases. The average age of ovarian cancer diagnosis in carriers of the I1307K allele (57.5 years) was not statistically different than the age for noncarriers (56.4 years; P = 0.70). Among the 1087 first-degree relatives, there were 23 cases of colorectal cancer; 3 of 100 relatives of probands with the I1307K allele (3.0%) had a history of colorectal cancer versus 20 of 987 relatives of probands without the I1307K allele (2.1%; relative risk, 1.48; 95% confidence interval, 0.45-4.88; P = 0.462). Relatives of the I1307K carriers had a risk of 38.0% for developing any cancer to age 80, similar to the risk for relatives of noncarriers of the I1307K allele (42.1%; P = 0.86). The average age of diagnosis of cancer of any type was not different between relatives of carriers (59.0 years) and noncarriers (60.4 years). In the Ashkenazi Jewish population, the I1307K allele is unlikely to increase the risk of ovarian cancer or of cancer in general.

Modification of BRCA1- and BRCA2-associated breast cancer risk by AIB1 genotype and reproductive history.

Women who have inherited a germ-line mutation in the BRCA1 or BRCA2 (BRCA1/2) genes have a greatly increased risk of developing breast cancer compared with the general population. However, there is also substantial interindividual variability in the occurrence of breast cancer among BRCA1/2 mutation carriers. We hypothesize that genes involved in endocrine signaling may modify the BRCA1/2-associated age-specific breast cancer penetrance. We studied the effect of alleles at the AIB1 gene using a matched case-control sample of 448 women with germ-line BRCA1/2 mutations. We found that these women were at significantly higher breast cancer risk if they carried alleles with at least 28 or 29 polyglutamine repeats at AIB1, compared with women who carried alleles with fewer polyglutamine repeats [odds ratio (OR), 1.59; 95% confidence interval (CI), 1.03-2.47 and OR, 2.85; 95% CI, 1.64-4.96, respectively]. Late age at first live birth and nulliparity have been associated with increased breast cancer risk. We observed increases in BRCA1/2-associated breast cancer risk in women who were either nulliparous or had their first live birth after age 30 (OR, 3.06; 95% CI, 1.52-6.16). Women were at significantly increased risk if they were nulliparous or had a late age at first live birth and had AIB1 alleles no shorter than 28 or 29 or more AIB1 polyglutamine repeats (OR, 4.62; 95% CI, 2.02-10.56 and OR, 6.97; 95% CI, 1.71-28.43, respectively) than women with none of these risk factors. Our results support the hypothesis that pathways involving endocrine signaling, as measured through AIB1 genotype and reproductive history, may have a substantial effect on BRCA1/2-associated breast cancer risk.

Germline BRCA1/2 mutations and p27(Kip1) protein levels independently predict outcome after breast cancer.

PURPOSE: Decreased levels of the cyclin-dependent kinase inhibitor p27(Kip1) in breast cancer are associated with a poor outcome. The prognostic significance of BRCA1/2 mutations is less clear, and the relationship between BRCA1/2 mutation status, p27(Kip1) protein levels, and outcome has not been studied. PATIENTS AND METHODS: Pathology blocks from 202 consecutive Ashkenazi Jewish women with primary invasive breast cancer were studied. Tumor DNA was tested for the three common BRCA1/2 founder mutations present in Ashkenazi Jews, and p27(Kip1) expression was evaluated by immunohistochemistry. The median follow-up was 6.4 years. RESULTS: Thirty-two tumors (16%) were positive for a BRCA1/2 mutation. Low p27(Kip1) expression was seen in 110 tumors (63%) and was significantly associated with BRCA1/2 mutations (odds ratio, 4.0; 95% confidence interval [CI], 1.4 to 11.1; P =.009). BRCA1/2 mutation carriers had a significantly worse 5-year distant disease-free survival (DDFS) compared with women without BRCA1/2 mutations (58% v 82%; P =.003). Similar results were seen for women whose tumors expressed low levels of p27(Kip1), compared with those with high levels (5-year DDFS, 68% v 93%; P<.0001). In a multivariate analysis, both BRCA1/2 mutation and low p27(Kip1) expression were associated with a shorter DDFS (relative risk [RR], 2.1; 95% CI, 1.0 to 4.3; P =.05; and RR, 3.9; 95% CI, 1.4 to 11.1; P =.01, respectively). CONCLUSION: In this study, we showed that BRCA1/2 mutations were associated with low levels of p27(Kip1) in breast cancer. Both BRCA1/2 and p27(Kip1) status were identified as independent prognostic factors.

Germ-line BRCA1 mutation is an adverse prognostic factor in Ashkenazi Jewish women with breast cancer.

Germ-line mutations in BRCA1 confer an increased risk of developing breast and ovarian cancer, but little is known about the clinical course of breast cancer in BRCA1 mutation carriers compared with noncarriers. Two recurrent BRCA1 mutations (185delAG and 5382insC) are common ( approximately 1.3%) in Ashkenazi Jews and account for about 20% of breast cancers diagnosed before age 40 in this group. We assayed paraffin-embedded tumor blocks from 117 unselected Ashkenazi Jewish women with primary breast cancer, diagnosed before age 65 at a single institution, for the presence of either of the two BRCA1 mutations. We reviewed the medical records and constructed survival curves for BRCA1-positive and -negative subgroups. Twelve of the women (10.3%) were found to carry BRCA1 mutations (eight mutations were 185delAG, and four were 5382insC). The probability of death from breast cancer in the first 5 years was 35.7% in the BRCA1 mutation-positive group and 4.3% in the 100 women without a mutation (P = 0.0023). The 5-year distant disease-free survival was 68.2% in BRCA1 mutation carriers and 88.7% in noncarriers (P = 0.019). These data suggest that breast cancer occurring in an Ashkenazi Jewish woman carrying a germ-line BRCA1 mutation has an adverse prognosis. This information is available before the diagnosis of breast cancer, and therefore, this finding may have important implications for prevention of breast cancer in BRCA1 mutation carriers.

Cutaneous malignant melanoma in women is uncommonly associated with a family history of melanoma in first-degree relatives: a case-control study.

Sun exposure is the principal cause of malignant melanoma, but other risk factors may be important. During their reproductive years women are at a greater risk for melanoma than men. We performed an age-matched case-control study of cutaneous malignant melanoma in 159 women attending a single oncology clinic in Montreal. A reported family history of cutaneous malignant melanoma in first-degree relatives was associated with a significantly increased risk of melanoma (adjusted relative risk: 4.28, P = 0.046). No subject was a member of a hereditary melanoma family (three or more cases of melanoma in first-degree relatives). As expected, variables related to sun exposure were also strong determinants of risk. Height was a significant risk factor, but the difference between the mean heights of cases and controls was only 2 cm (P = 0.009). The age of menarche of cases was lower than in controls (mean 12.70 and 13.08 years respectively, P = 0.036) but there was no significant elevation in risk associated with other reproductive variables. This study suggests that a family history of malignant melanoma is a significant risk factor, but that hereditary melanoma may be less common than is currently believed.

Familial risks of squamous cell carcinoma of the head and neck: retrospective case-control study.

OBJECTIVE: To determine the contribution of inheritance to the incidence of squamous cell carcinoma of the head and neck. DESIGN: Historical cohort study. First degree relatives of cases with squamous cell carcinoma of the head and neck made up the exposed cohort and first degree relatives of spouses of cases made up the comparison unexposed cohort. SETTING: Ear, nose, and throat clinic in a large metropolitan teaching hospital. SUBJECTS: 1429 first degree relatives of 242 index cases of squamous cell carcinoma of the head and neck; as controls, 934 first degree relatives of the spouses of 156 index cases. MAIN OUTCOME MEASURES: Relative risk of developing squamous cell carcinoma in first degree relatives of cases compared with risk in first degree relatives of spouses. RESULTS: The adjusted relative risk for developing head and neck cancer if the index case had squamous cell carcinoma of the head and neck was 3.79 (95% confidence interval 1.11 to 13.0). There were no significantly increased risks associated with a family history of cancer at other sites. The adjusted relative risk for squamous cell carcinoma of the head and neck was 7.89 (1.50 to 41.6) in first degree relatives of patients with multiple primary head and neck tumours. CONCLUSIONS: These data suggest that genetic factors are important in the aetiology of head and neck cancer, in particular for patients with multiple primary cancers. Given the prolonged exposure of these subjects to carcinogens, these genetic factors may have a role in modifying carcinogen activity or in host resistance to carcinogens. Inherited factors may be important in persons with environmentally induced cancers.

Expression of epidermal growth factor receptor in relation to BRCA1 status, basal-like markers and prognosis in breast cancer.

AIMS: BRCA1-related breast cancer is associated with a basal-like phenotype, and is frequently oestrogen receptor (ER) and HER2 negative. The expression of epidermal growth factor receptor (EGFR) has been considered to be one component of the basal-like phenotype, but no standard criteria exist. This study investigates the relationship between EGFR expression, BRCA1 status and basal markers with respect to clinicopathological associations and prognosis, in addition to evaluating different criteria for EGFR assessment by immunohistochemistry. METHODS: A tissue microarray comprising 230 available cases, from a series of primary invasive breast cancer diagnosed in Ashkenazi Jewish women during 1980-1995, was stained for EGFR using the Dako PharmDX kit, and evaluated by Webslide virtual microscopy. RESULTS: EGFR was positive in 9-19% according to different criteria. Expression was associated with BRCA1 carrier status and basal-like markers as negative ER, positive cytokeratin 5/6 and positive P-cadherin staining. EGFR was prognostically significant by univariate and multivariate analysis within the group carrying germ-line BRCA1 mutations. Histological grade, axillary lymph node status and P-cadherin status had significant independent value in the final multivariate model including all cases, whereas EGFR was not significant in this model. All five scoring systems gave comparable results concerning clinicopathological associations and patient outcome, although the most restrictive criteria (EGFR-HI) tended to be most sensitive in predicting BRCA1 status, a basal phenotype, and patient prognosis. CONCLUSIONS: EGFR expression, being present in 9-19% of the cases, was prognostically significant among BRCA1 mutated cases only. In multivariate survival analysis of all cases, no independent effect was seen. However, EGFR immunostaining might be relevant to predict the response to targeted therapy, and this should be studied further.

Cyclin E expression in breast cancer: predicting germline BRCA1 mutations, prognosis and response to treatment.

BACKGROUND: Elevated levels of the cell cycle protein cyclin E, and low levels of its inhibitor, p27(Kip1), have been associated with a poor prognosis following breast cancer. Some studies have found that germline mutations in the breast cancer susceptibility gene, BRCA1, are also associated with an inferior survival rate. The relationship between cyclin E/p27(Kip1) levels, BRCA1 status and outcome has not been studied in detail. PATIENTS AND METHODS: We analyzed a historical cohort of 288 Ashkenazi Jewish women who were diagnosed with breast cancer between 1980 and 1995 and were previously tested for BRCA1/2 mutations. Protein levels of cyclin E and p27(Kip1) were assessed by immunohistochemistry. Breast cancer-specific survival (BCSS) was the main outcome measured. RESULTS: The median follow-up was 8 years. Thirty tumors carried germline BRCA1 mutations. These tumors were more likely to have high cyclin E protein levels [odds ratio (OR) 9.5; P <0.001] and low p27(Kip1) protein levels (OR 2.8; P=0.03) than tumors from patients without BRCA1/2 mutations. High cyclin E expression level was the strongest predictor of BRCA1 germline mutations (multivariate OR 4.7; P=0.004). On univariate analysis, high cyclin E protein levels [relative risk (RR) 2.6; P <0.001] and low p27(Kip1) protein levels (RR 2.3; P=0.006) were significant prognostic factors for a poorer BCSS. In Cox multivariate models, high cyclin E levels remained an independent indicator of poor outcome only in the subgroup of patients who did not receive chemotherapy (P=0.002). CONCLUSIONS: In this ethnically restricted cohort, a high level of cyclin E is a characteristic of BRCA1-related breast cancer, and is a marker of poor prognosis following breast cancer, particularly in the absence of adjuvant chemotherapy.

Family history of cancer is a risk factor for squamous cell carcinoma of the head and neck in Brazil: a case-control study.

To determine the role of familial factors in head and neck cancer, we analysed data from a hospital-based case-control study of squamous cell carcinoma of the head and neck in Brazil. There were 754 cases of squamous cell carcinoma of the head and neck (SCCHN) and 1,507 age- and gender-matched hospital-based controls with non-malignant diseases. Subjects provided information on the occurrence of cancer in first-degree relatives, as well as about other risk factors, including tobacco and alcohol consumption. Relative risks (RRs) were estimated for developing mouth, pharynx and larynx cancer when cancers in relatives were observed. RRs were adjusted for age, sex, city of admission and alcohol and tobacco consumption. The RR for developing SCCHN if a first-degree relative had cancer at any site was significantly elevated at 1.97. The RR was 3.65 (95% CI: 1.97-6.76) if the relative had head and neck cancer. Significantly elevated risks for developing head and neck cancer were associated with siblings with head and neck cancer (RR = 8.57) and, to a lesser extent, with fathers with head and neck cancer (RR = 2.49). There was no significantly increased risk associated with mothers with head and neck cancer, but these tumours were rare among mothers. Our data show that familial, possibly genetic, factors are important in the aetiology of head and neck cancer.

Genetic implications of double primary cancers of the colorectum and endometrium.

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant condition predisposing to cancers of the colorectum and endometrium. Endometrial cancer is the most commonly occurring extracolonic cancer in HNPCC. Estimates of the cumulative incidence of endometrial cancer in women with mutations in the HNPCC genes range from 22-43%. In order to determine how frequently double primary cancers of the colorectum and endometrium are the result of a hereditary factor, we conducted a registry based study in Ontario and Quebec, Canada. We obtained pedigrees on 80 women diagnosed with double primary cancers of the colorectum and endometrium at less than 70 years of age. Family histories of cancer were obtained for all first degree relatives of these women and cancer rates were compared with age standardised provincial incidence rates in order to estimate the relative risks. There was a total of 82 cancers observed in relatives below the age of 55, compared with 31.2 expected, giving a relative risk of 2.6 (95% confidence interval (CI) 2.1-3.3). The relative risk for colorectal cancer below 55 was 16.1 (95% CI 11.6-21.8). This risk decreased with increasing age of onset of cancers in probands. For probands with both colorectal and endometrial cancer diagnosed under the age of 55, the relative risk of colorectal cancer in relatives below the age of 55 was 30.5 (95% CI 18.8-46.6). Similar patterns were observed for endometrial and pancreatic cancer. There were non-significant increases in rates of cancer of the oesophagus, stomach, small intestine, and bladder. There was no increased risk of breast cancer. The risk of lung cancer was decreased, especially in older relatives. Our findings indicate the presence of a significant genetic component of cancer in women with double primary cancers of the colorectum and endometrium.

Glomeruloid microvascular proliferation is associated with p53 expression, germline BRCA1 mutations and an adverse outcome following breast cancer.

Glomeruloid microvascular proliferation (GMP) in breast cancer independently adversely affected survival (relative risk 1.9, 95% CI: 1.2-3.0), particularly among women who received adjuvant chemotherapy (10-year survival 27 vs 69%, P=0.0003), and was significantly associated with p53 overexpression and BRCA1 germline mutations. The presence of GMP may influence treatment decisions.

Risk factors for familial and sporadic ovarian cancer among French Canadians: a case-control study.

OBJECTIVE: The objective was to compare risk factors between familial and sporadic ovarian cancer by means of a case-control approach. STUDY DESIGN: We conducted a case-control study among French Canadian women in Montreal during 1995-1996. One hundred seventy women 20 to 84 years old with histologically confirmed diagnoses of primary ovarian carcinomas or borderline tumors were interviewed concerning their reproductive, family, and medical histories. During the same period 170 randomly selected population control subjects, frequency-matched to the case patients according to age and ethnic group, were also interviewed. Unconditional logistic regression methods were used for data analysis. RESULTS: The major factors influencing the risk of development of ovarian cancer were as follows: (1) family history of breast or ovarian cancer, (2) a late age at use of oral contraceptives (a protective effect), and (3) a late age at last childbirth (a protective effect for familial case patients only). CONCLUSION: These factors had equally great impacts in familial and sporadic cases, implying that the underlying mechanisms of carcinogenesis in sporadic and familial ovarian cancer may be similar and that hereditary ovarian cancer may be preventable.

The effect of the I1307K APC polymorphism on the clinicopathological features and natural history of breast cancer.

The I1307K polymorphism in APC has been found to predispose to colorectal cancer in Ashkenazi Jews, and has recently been associated with an increased risk for breast cancer in the same population. In that study, we genotyped 205 paraffin-embedded breast cancers from Ashkenazi Jewish women diagnosed below the age of 65. We now present an extended analysis, with clinicopathological correlations between carriers of I1307K and non-carriers. Twenty-four of 209 cases (11.5%, 95% confidence interval 7.5-16.6) were found to carry the I1307K polymorphism. When stratifying the data by other relevant clinicopathological variables, we observed no association between the presence of this polymorphism and age at diagnosis (P = 0.52), grade (P = 0.074), tumour size (P = 0.99), lymph node status (P = 0.82), oestrogen receptor status (P = 0.23) or P53 immunoreactivity (P = 0.80). The breast-cancer specific 5-year survival for women with I1307 K polymorphism was 88.9% compared with 81.6% in women without I1307K (P = 0.34). Using microdissected samples and direct sequencing, no somatic mutations were observed in any of the 24 I1307K-positive cases. Single-strand conformation analysis of 158 of the I1307K-negative breast cancers that were available for study revealed no mobility shifts. We conclude that the presence of the I1307K polymorphism does not appear to be associated with any particular clinicopathological feature of breast cancer and importantly, does not affect the prognosis.

Tamoxifen and risk of contralateral breast cancer in BRCA1 and BRCA2 mutation carriers: a case-control study. Hereditary Breast Cancer Clinical Study Group.

BACKGROUND: Women with a mutation in BRCA1 or BRCA2 have a high risk of developing breast cancer and of contralateral cancer after the initial diagnosis of breast cancer. Tamoxifen protects against contralateral breast cancer in the general population, but whether it protects against contralateral breast cancer in BRCA1 or BRCA2 mutation carriers is not known. METHODS: We compared 209 women with bilateral breast cancer and BRCA1 or BRCA2 mutation (bilateral-disease cases), with 384 women with unilateral disease and BRCA1 or BRCA2 mutation (controls) in a matched case-control study. Age and age at diagnosis of breast cancer (range 24-74 years) were much the same in bilateral-disease cases and controls, and both groups had been followed up for the same time for a second primary breast cancer. History of tamoxifen use for first breast cancer was obtained by interview, or by self-administered questionnaire. FINDINGS: The multivariate odds ratio for contralateral breast cancer associated with tamoxifen use was 0.50 (95% CI 0.28-0.89). Tamoxifen protected against contralateral breast cancer for carriers of BRCA1 mutations (odds ratio 0.38, 95% CI 0.19-0.74) and for those with BRCA2 mutations (0.63, 0.20-1.50). In women who used tamoxifen for 2-4 years, the risk of contralateral breast cancer was reduced by 75%. A reduction in risk of contralateral cancer was also seen with oophorectomy (0.42, 0.22-0.83) and with chemotherapy (0-40, 0.26-0.60). INTERPRETATION: Tamoxifen use reduces the risk of contralateral breast cancer in women with pathogenic mutations in the BRCA1 or BRCA2 gene. The protective effect of tamoxifen seems independent of that of oophorectomy.