Breast cancer risk after salpingo-oophorectomy in healthy BRCA1/2 mutation carriers: revisiting the evidence for risk reduction.

BACKGROUND: Previous studies have reported a breast cancer (BC) risk reduction of approximately 50% after risk-reducing salpingo-oophorectomy (RRSO) in BRCA1/2 mutation carriers, but may have been subject to several types of bias. The purpose of this nationwide cohort study was to assess potential bias in the estimated BC risk reduction after RRSO. METHODS: We selected BRCA1/2 mutation carriers from an ongoing nationwide cohort study on Hereditary Breast and Ovarian Cancer in the Netherlands (HEBON). First, we replicated the analytical methods as previously applied in four major studies on BC risk after RRSO. Cox proportional hazards models were used to calculate hazard ratios and conditional logistic regression to calculate odds ratios. Secondly, we analyzed the data in a revised design in order to further minimize bias using an extended Cox model with RRSO as a time-dependent variable to calculate the hazard ratio. The most important differences between our approach and those of previous studies were the requirement of no history of cancer at the date of DNA diagnosis and the inclusion of person-time preceding RRSO. RESULTS: Applying the four previously described analytical methods and the data of 551 to 934 BRCA1/2 mutation carriers with a median follow-up of 2.7 to 4.6 years, the odds ratio was 0.61 (95% confidence interval [CI] = 0.35 to 1.08), and the hazard ratios were 0.36 (95% CI = 0.25 to 0.53), 0.62 (95% CI = 0.39 to 0.99), and 0.49 (95% CI = 0.33 to 0.71), being similar to earlier findings. For the revised analysis, we included 822 BRCA1/2 mutation carriers. After a median follow-up period of 3.2 years, we obtained a hazard ratio of 1.09 (95% CI = 0.67 to 1.77). CONCLUSION: In previous studies, BC risk reduction after RRSO in BRCA1/2 mutation carriers may have been overestimated because of bias. Using a design that maximally eliminated bias, we found no evidence for a protective effect.

Survival and contralateral breast cancer in CHEK2 1100delC breast cancer patients: impact of adjuvant chemotherapy.

BACKGROUND: We assessed the sensitivity to adjuvant chemotherapy in cell cycle checkpoint kinase 2 (CHEK2) vs non-CHEK2 breast cancer patients by comparing the contralateral breast cancer incidence and distant disease-free and breast cancer-specific survival between both groups, stratified for adjuvant chemotherapy. METHODS: One Dutch hereditary non-BRCA1/2 breast cancer patient cohort (n=1220) and two Dutch cohorts unselected for family history (n=1014 and n=2488, respectively) were genotyped for CHEK2 1100delC. Hazard ratios for contralateral breast cancer, distant disease-free and breast cancer-specific death for mutation carriers vs noncarriers were calculated using the Cox proportional hazard method, stratified for adjuvant chemotherapy. RESULTS: The CHEK2 mutation carriers (n=193) had an increased incidence of contralateral breast cancer (multivariate hazard ratio 3.97, 95% confidence interval 2.59-6.07). Distant disease-free and breast cancer-specific survival were similar in the first 6 years in mutation carriers compared with noncarriers, but diverted as of 6 years after breast cancer diagnosis (multivariate hazard ratios and 95% confidence intervals 2.65 (1.79-3.93) and 2.05 (1.41-2.99), respectively). No significant interaction between CHEK2 and adjuvant chemotherapy was observed. CONCLUSIONS: The CHEK2 1100delC-associated breast cancer is associated with a higher contralateral breast cancer rate as well as worse survival measures beyond 6 years after diagnosis. No differential sensitivity to adjuvant chemotherapy was observed in CHEK2 patients.

Substantial breast cancer risk reduction and potential survival benefit after bilateral mastectomy when compared with surveillance in healthy BRCA1 and BRCA2 mutation carriers: a prospective analysis.

BACKGROUND: To prospectively assess the efficacy of bilateral risk-reducing mastectomy (BRRM) when compared with surveillance on breast cancer (BC) risk and mortality in healthy BRCA1 and BRCA2 mutation carriers. PATIENTS AND METHODS: Five hundred and seventy healthy female mutation carriers (405 BRCA1, 165 BRCA2) were selected from the institutional Family Cancer Clinic database. Eventually, 156 BRCA1 and 56 BRCA2 mutation carriers underwent BRRM. The effect of BRRM versus surveillance was estimated using Cox models. RESULTS: During 2037 person-years of observation (PYO), 57 BC cases occurred in the surveillance group versus zero cases during 1379 PYO in the BRRM group (incidence rates, 28 and 0 per 1000 PYO, respectively). In the surveillance group, four women died of BC, while one woman in the BRRM group presented with metastatic BC 3.5 years after BRRM (no primary BC), and died afterward, yielding a HR of 0.29 (95% CI 0.02-2.61) for BC-specific mortality. CONCLUSIONS: In healthy BRCA1/2 mutation carriers, BRRM when compared with surveillance reduces BC risk substantially, while longer follow-up is warranted to confirm survival benefits.

PTEN in colorectal cancer: a report on two Cowden syndrome patients.

Heterozygous germline PTEN mutations cause Cowden syndrome. The risk of colorectal cancer in Cowden patients, however, remains a matter of debate. We describe two patients presenting with colorectal cancer at a young age (28 and 39 years) and dysmorphisms fitting the Cowden spectrum. Heterozygous germline mutations in PTEN were found in both patients. Moreover, analysis of the resected colorectal cancer specimens revealed loss of heterozygosity at the PTEN locus with retention of the mutated alleles, and greatly reduced or absent PTEN expression. Histologically and molecularly, the tumours showed resemblance with sporadic colorectal cancers, although they had prominent fibrotic stroma. Our data indicate that PTEN loss was involved in carcinogenesis in the two patients, supporting that colorectal cancer is part of the Cowden syndrome-spectrum. This is in line with data on sporadic colorectal cancer, mice studies and emerging epidemiological data on Cowden syndrome. Although the exact role of germline PTEN mutations in the carcinogenesis of colorectal cancer remains unclear, we think that Cowden syndrome should be in the differential diagnosis of colorectal cancer certainly in view of the possible prognostic and therapeutic consequences. Prospective follow-up and surveillance of PTEN mutation carriers from the age of 25 to 30 years in a study setting should clarify this issue.

Relative frequencies of cystic fibrosis mutations in The Netherlands as an illustration of significant regional variation in a small country.

Cystic fibrosis (CF) is one of the most common autosomal recessive disorders in white populations. Significant regional differences in CF mutations among affected individuals have been reported. We have studied the geographic distribution of the relative frequencies of the three most common Dutch CF mutations, deltaF508, A455E, and G542X, by analyzing data on area of residence of CF patients. Significantly higher relative frequencies of the A455E mutation and the G542X mutation were observed in the South-West and the South-East, respectively. A uniform distribution of relative frequencies was found for the deltaF508 mutation. The results of our study show that, even in a small country such as The Netherlands, certain CF mutations may be more common in one region than in another.

Prevalence of delta F508 cystic fibrosis carriers in The Netherlands: logistic regression on sex, age, region of residence and number of offspring.

An average cystic fibrosis (CF) carrier frequency of 1 in 25 in Europe is cited in numerous reports, although a great variability in estimated prevalences has been found in different European populations. The estimates of these frequencies were based on numbers of CF patients before identification of the gene in 1989. Here we report the results of a study to determine the carrier frequency of the delta F508 mutation in The Netherlands by analyzing mouthwashes and matched blood samples from 11654 blood donors all over the country. We analyzed possible relationships between a number of theoretically explanatory variables and the delta F508 carrier frequency by means of univariate and multivariate logistic regression. These variables were: distance of the blood banks from the northeastern part of the country (distance); whether the blood donors knew that we were looking for a CF mutation; sex and age of the donor; and number of children of the donor (family size). We detected a delta F508 carrier frequency of 1 in 42 (95% CI 1/37-1/47) in The Netherlands. If we assume that the relative frequency of the delta F508 mutation among carriers and patients is comparable in The Netherlands, this gives an estimated overall CF carrier frequency of 1 in 32 (95% CI 1/28-1/36), significantly less than 1 in 25. The univariate logistic regression analysis of the effects of the explanatory variables on the carrier frequency revealed no significant relationships, except for an increase in carrier frequency with increasing distance from the northeastern region. In the multivariate analysis with all five independent variables, distance, age and family size were significantly related to the carrier frequency, but sex and CF information were not. There was a significant interaction between age and family size. In our final model, distance, age and family size were positively related to the carrier frequency, while the interaction of age with family size showed a negative relation. These results confirm that there is a gradient in gene frequency with low frequencies in the northeastern part of the country and high frequencies in the southern part. They also suggest a relation of age and family size with carrier frequency. This relation, however, is too complex to be explained by heterozygote advantage.

Validation of the determination of deltaF508 mutations of the cystic fibrosis gene in over 11 000 mouthwashes.

Mouthwashes can be used as a DNA resource for mutation detection and, because collection and DNA isolation is simple and cheap, they could in particular, be used for large numbers of samples. To determine the failure rate (the proportion of mouth samples in which no PCR product was obtained) and the specificity of buccal epithelial cell mutation detection in large numbers of samples, we collected mouthwashes and blood samples from 11 413 blood donors and tested the mouthwashes for the deltaF508 mutation, which has an estimated frequency Of 75% among cystic fibrosis chromosomes in The Netherlands. Blood samples were tested for the deltaF508 mutations only if the mutation was identified in the mouthwash or in the case of a failure to obtain PCR products. The sensitivity of the test was determined in mouthwashes of 75 deltaF508 carriers known from earlier family studies. These samples were offered blindly between the mouthwashes of the blood donors. Both specificity and sensitivity of the mouthwash procedure were 100%. The overall failure rate was 5.6%. This large figure was caused mainly by insufficient rinsing of the mouth in one particular blood bank. Exclusion of the results of this blood bank reduced the failure rate to 1.8%. Our results also confirmed that for a large number of samples the mouthwash procedure is suitable for mutation detection and, with proper instructions, can be used in community screening.

Number and sex of offspring of delta F508 carriers outside cystic fibrosis families.

Number and sex of offspring were determined in a group of 7,841 randomly selected blood donors who were screened for the delta F508 mutation. We did not find any evidence for differences in number or sex ratio of offspring between delta F508 carriers and non-carriers.