No evidence of excess breast cancer risk among mutation-negative women from BRCA mutation-positive families

Cost-Effectiveness of BRCA 1/2 Genetic Test and Preventive Strategies: Using Real-World Data From an Upper-Middle Income Country

Although BRCA1/2 genetic testing in developed countries is part of the reality for high-risk patients for hereditary breast and ovarian cancer (HBOC), the same is not true for upper-middle-income countries. For that reason, this study aimed to evaluate whether the BRCA1/2 genetic test and preventive strategies for women at high risk for HBOC are cost-effective compared to not performing these strategies in an upper-middle-income country. Adopting a payer perspective, a Markov model with a time horizon of 70 years was built to delineate the health states for a cohort of healthy women aged 30 years that fulfilled the BRCA1/2 testing criteria according to the guidelines. Transition probabilities were calculated based on real-world data of women tested for BRCA1/2 germline mutations in a cancer reference hospital from 2011 to 2020. We analyzed 275 BRCA mutated index cases and 356 BRCA mutation carriers that were first- or second-degree relatives of the patients. Costs were based on the Brazilian public health system reimbursement values. Health state utilities were retrieved from literature. The BRCA1/2 genetic test and preventive strategies result in more quality-adjusted life years (QALYs) and costs with an incremental cost-effectiveness ratio of R$ 11,900.31 (U$ 5,504.31)/QALY. This result can represent a strong argument in favor of implementing genetic testing strategies for high-risk women even in countries with upper-middle income, considering not only the cancer prevention possibilities associated with the genetic testing but also its cost-effectiveness to the health system. These strategies are cost-effective, considering a willingness-to-pay threshold of R$ 25,000 (U$ 11,563.37)/QALY, indicating that the government should consider offering them for women at high risk for HBOC. The results were robust in deterministic and probabilistic sensitivity analyses.

BRCA1/2 variants of unknown significance in hereditary breast and ovarian cancer (HBOC) syndrome: looking for the hidden meaning

Hereditary breast and ovarian cancer syndrome is caused by germline mutations in BRCA1/2 genes. These genes are very large and their mutations are heterogeneous and scattered throughout the coding sequence. In addition to the above-mentioned mutations, variants of uncertain/unknown significance (VUSs) have been identified in BRCA genes, which make more difficult the clinical management of the patient and risk assessment. In the last decades, several laboratories have developed different databases that contain more than 2000 variants for the two genes and integrated strategies which include multifactorial prediction models based on direct and indirect genetic evidence, to classify the VUS and attribute them a clinical significance associated with a deleterious, high-low or neutral risk. This review provides a comprehensive overview of literature studies concerning the VUSs, in order to assess their impact on the population and provide new insight for the appropriate patient management in clinical practice.

Risks of breast or ovarian cancer in BRCA1 or BRCA2 predictive test negatives: findings from the EMBRACE study

PURPOSE

BRCA1/BRCA2 predictive test negatives are proven noncarriers of a BRCA1/BRCA2 mutation that is carried by their relatives. The risk of developing breast cancer (BC) or epithelial ovarian cancer (EOC) in these women is uncertain. The study aimed to estimate risks of invasive BC and EOC in a large cohort of BRCA1/BRCA2 predictive test negatives.

METHODS

We used cohort analysis to estimate incidences, cumulative risks, and standardized incidence ratios (SIRs).

RESULTS

A total of 1,895 unaffected women were eligible for inclusion in the BC risk analysis and 1,736 in the EOC risk analysis. There were 23 incident invasive BCs and 2 EOCs. The cumulative risk of invasive BC was 9.4% (95% confidence interval (CI) 5.9-15%) by age 85 years and the corresponding risk of EOC was 0.6% (95% CI 0.2-2.6%). The SIR for invasive BC was 0.93 (95% CI 0.62-1.40) in the overall cohort, 0.85 (95% CI 0.48-1.50) in noncarriers from BRCA1 families, and 1.03 (95% CI 0.57-1.87) in noncarriers from BRCA2 families. The SIR for EOC was 0.79 (95% CI 0.20-3.17) in the overall cohort.

CONCLUSION

Our results did not provide evidence for elevated risks of invasive BC or EOC in BRCA1/BRCA2 predictive test negatives.

Breast Cancer Genetics and Indications for Prophylactic Mastectomy

As more genetic information becomes available to inform breast cancer treatment, screening, and risk-reduction approaches, clinicians must become more knowledgeable about possible genetic testing and prevention strategies, including outcomes, benefits, risks, and limitations. The aim of this article is to define and distinguish high- and moderate-risk breast cancer predisposition genes, summarize the clinical recommendations that may be considered based on the identification of pathogenic variants (mutations) in these genes, and indications for risk-reducing and contralateral prophylactic mastectomy.

Can chimerism explain breast/ovarian cancers in BRCA non-carriers from BRCA-positive families?

Hereditary breast and ovarian cancer syndrome (HBOC) is most frequently caused by mutations in BRCA1 or BRCA2 (in short, BRCA) genes. The incidence of hereditary breast and ovarian cancer in relatives of BRCA mutation carriers who test negative for the familial mutation (non-carriers) may be increased. However, the data is controversial, and at this time, these individuals are recommended the same cancer surveillance as general population. One possible explanation for BRCA phenocopies (close relatives of BRCA carriers who have developed cancer consistent with HBOC but tested negative for a familial mutation) is natural chimerism where lack of detectable mutation in blood may not rule out the presence of the mutation in the other tissues. To test this hypothesis, archival tumor tissue from eleven BRCA phenocopies was investigated. DNA from the tumor tissue was analyzed using sequence-specific PCR, capillary electrophoresis, and pyrosequencing. The familial mutations were originally detected in the patients’ first-degree relatives by commercial testing. The same testing detected no mutations in the blood of the patients under study. The test methods targeted only the known familial mutation in the tumor tissue. Tumor diagnoses included breast, ovarian, endometrial and primary peritoneal carcinoma. None of the familial mutations were found in the tumor samples tested. These results do not support, but do not completely exclude, the possibility of chimerism in these patients. Further studies with comprehensive sequence analysis in a larger patient group are warranted as a chimeric state would further refine the predictive value of genetic testing to include BRCA phenocopies.

Multi-gene Panel Testing in Breast Cancer Management

Hereditary predisposition accounts for approximately 10% of all breast cancers and is mostly associated with germline mutations in high-penetrance genes encoding for proteins participating in DNA repair through homologous recombination (BRCA1 and BRCA2). With the advent of massive parallel next-generation DNA sequencing, simultaneous analysis of multiple genes with a short turnaround time and at a low cost has become possible. The clinical validity and utility of multi-gene panel testing is getting better characterized as more data on the significance of moderate-penetrance genes are collected from large, cancer genetic testing studies. In this chapter, we attempt to provide a general guide for interpretation of panel gene testing in breast cancer and use of the information obtained for clinical decision-making.

No evidence of excessive cancer screening in female noncarriers from BRCA1/2 mutation-positive families

BACKGROUND

In families with a proven BRCA1/2 mutation, women not carrying the familial mutation should follow the cancer screening recommendations applying to women in the general population. In the present study, we evaluated the cancer screening practices of unaffected noncarriers from families with a proven BRCA mutation, and we assessed the role of family history in their screening practices.

METHODS

Self-report data were provided retrospectively by 220 unaffected female noncarriers for periods of up to 10 years (mean: 4.3 years) since disclosure of their BRCA1/2 genetic test result. A ratio for the annual frequency of breast and ovarian cancer screening exams (mammography, breast ultrasonography, breast magnetic resonance imaging, transvaginal or pelvic ultrasound, cancer antigen 125 testing) was calculated as number of screening exams divided by the number of years in the individual observation period.

RESULTS

The annual average for mammography exams was 0.15, 0.4, 0.56, and 0.71 in women 30-39, 40-49, 50-59, and 60-69 years of age respectively. The uptake of other breast and ovarian cancer screening exams was very low. Mammography and breast ultrasonography and magnetic resonance imaging were generally more frequent among participants with at least 1 first-degree relative affected by breast cancer.

CONCLUSIONS

In most noncarriers, screening practices are consistent with the guidelines concerning women in the general population. When noncarriers adopt screening behaviours that are different from those that would be expected for average-risk women, those behaviours are influenced by their familial cancer history.

IMPACT

Decision tools might help female noncarriers to be involved in their follow-up in accordance with their genetic status and their family history, while taking into account the benefits and disadvantages of cancer screening.

No evidence of increased breast cancer risk for proven noncarriers from BRCA1 and BRCA2 families

In families screened for mutations in the BRCA1 or BRCA2 genes and found to have a segregating mutation the breast cancer risk for women shown not to carry the family-specific mutation might be at above "average" risk. We assessed the risk of breast cancer in a clinic based cohort of 725 female proven noncarriers in 239 BRCA1 and BRCA2 families compared with birth-matched controls from the Danish Civil Registration System. Prospective analysis showed no significantly increased risk for breast cancer in noncarriers with a hazard ratio of 0.67 [95 % confidence interval (CI) 0.32-1.42, p = 0.29] for all family members who tested negative and 0.87 (95 % CI 0.38-1.97, p = 0.73) for non-carries who were first-degree relatives of mutation carriers. Proven noncarriers from BRCA1 and BRCA2 families have no markedly increased risk for breast cancer compared to the general population, and our data do not suggest targeted breast cancer surveillance for noncarriers from BRCA1 and BRCA2 families.

Revertant mosaicism for family mutations is not observed in BRCA1/2 phenocopies

In BRCA1/2 families, early-onset breast cancer (BrCa) cases may be also observed among non-carrier relatives. These women are considered phenocopies and raise difficult counselling issues concerning the selection of the index case and the residual risks estimate in negative family members. Few studies investigated the presence of potential genetic susceptibility factors in phenocopies, mainly focussing on BrCa-associated single-nucleotide polymorphisms. We hypothesized that, as for other Mendelian diseases, a revertant somatic mosaicism, resulting from spontaneous correction of a pathogenic mutation, might occur also in BRCA pedigrees. A putative low-level mosaicism in phenocopies, which has never been investigated, might be the causal factor undetected by standard diagnostic testing. We selected 16 non-carriers BrCa-affected from 15 BRCA1/2 families, and investigated the presence of mosaicism through MALDI-TOF mass spectrometry. The analyses were performed on available tumour samples (7 cases), blood leukocytes, buccal mucosa and urine samples (2 cases) or on blood only (7 cases). In one family (n.8), real-time PCR was also performed to analyse the phenocopy and her healthy parents. On the 16 phenocopies we did not detect the family mutations neither in the tumour, expected to display the highest mutation frequency, nor in the other analysed tissues. In family 8, all the genotyping assays did not detect mosaicism in the phenocopy or her healthy parents, supporting the hypothesis of a de novo occurrence of the BRCA2 mutation identified in the proband. These results suggest that somatic mosaicism is not likely to be a common phenomenon in BRCA1/2 families. As our families fulfilled high-risk selection criteria, other genetic factors might be responsible for most of these cases and have a significant impact on risk assessment in BRCA1/2 families. Finally, we found a de novo BRCA2 mutation, suggesting that, although rare, this event should be taken into account in the evaluation of high-risk families.

Analysis of chromosomal radiosensitivity of healthy BRCA2 mutation carriers and non-carriers in BRCA families with the G2 micronucleus assay

Breast cancer risk drastically increases in individuals with a heterozygous germline BRCA1 or BRCA2 mutation, while it is estimated to equal the population risk for relatives without the familial mutation (non-carriers). The aim of the present study was to use a G2 phase-specific micronucleus assay to investigate whether lymphocytes of healthy BRCA2 mutation carriers are characterized by increased radiosensitivity compared to controls without a family history of breast/ovarian cancer and how this relates to healthy non-carrier relatives. BRCA2 is active in homologous recombination, a DNA damage repair pathway, specifically active in the late S/G2 phase of the cell cycle. We found a significantly increased radiosensitivity in a cohort of healthy BRCA2 mutation carriers compared to individuals without a familial history of breast cancer (P=0.046; Mann-Whitney U test). At the individual level, 50% of healthy BRCA2 mutation carriers showed a radiosensitive phenotype (radiosensitivity score of 1 or 2), whereas 83% of the controls showed no radiosensitivity (P=0.038; one-tailed Fishers exact test). An odds ratio of 5 (95% CI, 1.07–23.47) indicated an association between the BRCA2 mutation and radiosensitivity in healthy mutation carriers. These results indicate the need for the gentle use of ionizing radiation for either diagnostic or therapeutic use in BRCA2 mutation carriers. We detected no increased radiosensitivity in the non-carrier relatives.

Incorporating truncating variants in PALB2, CHEK2, and ATM into the BOADICEA breast cancer risk model

PURPOSE

The proliferation of gene panel testing precipitates the need for a breast cancer (BC) risk model that incorporates the effects of mutations in several genes and family history (FH). We extended the BOADICEA model to incorporate the effects of truncating variants in PALB2, CHEK2, and ATM.

METHODS

The BC incidence was modeled via the explicit effects of truncating variants in BRCA1/2, PALB2, CHEK2, and ATM and other unobserved genetic effects using segregation analysis methods.

RESULTS

The predicted average BC risk by age 80 for an ATM mutation carrier is 28%, 30% for CHEK2, 50% for PALB2, and 74% for BRCA1 and BRCA2. However, the BC risks are predicted to increase with FH burden. In families with mutations, predicted risks for mutation-negative members depend on both FH and the specific mutation. The reduction in BC risk after negative predictive testing is greatest when a BRCA1 mutation is identified in the family, but for women whose relatives carry a CHEK2 or ATM mutation, the risks decrease slightly.

CONCLUSIONS

The model may be a valuable tool for counseling women who have undergone gene panel testing for providing consistent risks and harmonizing their clinical management. A Web application can be used to obtain BC risks in clinical practice (http://ccge.medschl.cam.ac.uk/boadicea/).Genet Med 18 12, 1190-1198.

BRCA1 Circos: a visualisation resource for functional analysis of missense variants

BACKGROUND

Inactivating germline mutations in the tumour suppressor gene BRCA1 are associated with a significantly increased risk of developing breast and ovarian cancer. A large number (>1500) of unique BRCA1 variants have been identified in the population and can be classified as pathogenic, non-pathogenic or as variants of unknown significance (VUS). Many VUS are rare missense variants leading to single amino acid changes. Their impact on protein function cannot be directly inferred from sequence information, precluding assessment of their pathogenicity. Thus, functional assays are critical to assess the impact of these VUS on protein activity. BRCA1 is a multifunctional protein and different assays have been used to assess the impact of variants on different biochemical activities and biological processes.

METHODS AND RESULTS

To facilitate VUS analysis, we have developed a visualisation resource that compiles and displays functional data on all documented BRCA1 missense variants. BRCA1 Circos is a web-based visualisation tool based on the freely available Circos software package. The BRCA1 Circos web tool (http://research.nhgri.nih.gov/bic/circos/) aggregates data from all published BRCA1 missense variants for functional studies, harmonises their results and presents various functionalities to search and interpret individual-level functional information for each BRCA1 missense variant.

CONCLUSIONS

This research visualisation tool will serve as a quick one-stop publically available reference for all the BRCA1 missense variants that have been functionally assessed. It will facilitate meta-analysis of functional data and improve assessment of pathogenicity of VUS.

Theory development from studies with young women with breast cancer who are BRCA mutation negative

Researchers and practitioners can use inductively derived theory to direct their research and practice. This article describes the ongoing development of a theory that can assist in explaining experiences of young women with breast cancer who have genetic testing for the BRCA mutation. Seventeen BRCA-negative women with breast cancer from a larger grounded theory study were interviewed. While receiving a negative BRCA mutation test result subsequent to a breast cancer diagnosis was described as a relief, the information was also confusing. The author's published Theory of Genetic Vulnerability is expanded to incorporate the outcomes of this analysis.

Proven non-carriers in BRCA families have an earlier age of onset of breast cancer

BACKGROUND

Risk estimates for proven non-carriers in BRCA mutation families are inconsistent for breast cancer and lacking for ovarian cancer. We aimed to assess the age-related risks for breast and ovarian cancer for proven non-carriers in these families.

METHODS

A consecutive cohort study ascertained 464 proven non-carriers who had a first-degree relative with a pathogenic BRCA mutation. Kaplan-Meier analyses were used to estimate the age-related cancer risks, and we calculated standardised incidence ratios.

RESULTS

In the 464 non-carriers, 17 breast cancers and two ovarian cancers were detected at a mean age of 47 years (95% confidence interval (CI) 32-61) and 49 years (95% CI 32-67), respectively. Overall, by the age of 50, the breast and ovarian cancer risks among non-carriers were 6.4% (95% CI 2.9-9.8%) and 0.4% (95% CI 0-1.3%), of which the breast cancer risk was statistically significantly higher than the risk in the general population. In particular, the number of breast cancers among non-carriers in BRCA1 families was higher than expected for the general population (standardised incidence ratio (SIR) 2.0, 95% CI 1.1-3.3). In the BRCA1 cohort, the mean number of breast cancer cases was higher in families in which non-carriers were diagnosed before the age of 50 (p=0.04).

CONCLUSION

The age at diagnosis of breast cancer in non-carriers in BRCA mutation families is younger than expected, yielding an increased risk in the fifth decade. This effect is most evident in BRCA1 families. If our results are confirmed by others, this could affect the advice given on breast cancer screening to proven non-carriers between the age of 40 and 50 in such families.

Comparison of the screening practices of unaffected noncarriers under 40 and between 40 and 49 in BRCA1/2 families

This study aimed to 1) compare the cancer screening practices of unaffected noncarrier women under 40 and those aged 40 to 49, following the age-based medical screening guidelines, and 2) consider the way the patients justified their practices of screening or over-screening. For this study, 131 unaffected noncarriers-77 women under age 40 and 54 between 40 and 49, all belonging to a BRCA1/2 family-responded to a questionnaire on breast or ovarian cancer screenings they had undergone since receiving their negative genetic test results, their motives for seeking these screenings, and their intentions to pursue these screenings in the future. Unaffected noncarriers under age 40 admitted practices that could be qualified as over-screening. Apart from mammogram and breast ultrasounds, which the women under 40 reported seeking less often, these women's screening practices were comparable to those of women between 40 and 49. Cancer prevention and a family history of cancer were the two most frequently cited justifications for pursuing these screenings. We suggest that health care professionals discuss with women under 50 the ineffectiveness of breast and ovarian cancer screenings so that they will adapt their practices to conform to medical guidelines and limit their exposure to the potentially negative impacts of early cancer screening.

Evidence that BRCA1- or BRCA2-associated cancers are not inevitable

Inheriting a BRCA1 or BRCA2 gene mutation can cause a deficiency in repairing complex DNA damage. This step leads to genomic instability and probably contributes to an inherited predisposition to breast and ovarian cancer. Complex DNA damage has been viewed as an integral part of DNA replication before cell division. It causes temporary replication blocks, replication fork collapse, chromosome breaks and sister chromatid exchanges (SCEs). Chemical modification of DNA may also occur spontaneously as a byproduct of normal processes. Pathways containing BRCA1 and BRCA2 gene products are essential to repair spontaneous complex DNA damage or to carry out SCEs if repair is not possible. This scenario creates a theoretical limit that effectively means there are spontaneous BRCA1/2-associated cancers that cannot be prevented or delayed. However, much evidence for high rates of spontaneous DNA mutation is based on measuring SCEs by using bromodeoxyuridine (BrdU). Here we find that the routine use of BrdU has probably led to overestimating spontaneous DNA damage and SCEs because BrdU is itself a mutagen. Evidence based on spontaneous chromosome abnormalities and epidemiologic data indicates strong effects from exogenous mutagens and does not support the inevitability of cancer in all BRCA1/2 mutation carriers. We therefore remove a theoretical argument that has limited efforts to develop chemoprevention strategies to delay or prevent cancers in BRCA1/2 mutation carriers.

Colorectal and other cancer risks for carriers and noncarriers from families with a DNA mismatch repair gene mutation: a prospective cohort study

PURPOSE

To determine whether cancer risks for carriers and noncarriers from families with a mismatch repair (MMR) gene mutation are increased above the risks of the general population.

PATIENTS AND METHODS

We prospectively followed a cohort of 446 unaffected carriers of an MMR gene mutation (MLH1, n = 161; MSH2, n = 222; MSH6, n = 47; and PMS2, n = 16) and 1,029 their unaffected relatives who did not carry a mutation every 5 years at recruitment centers of the Colon Cancer Family Registry. For comparison of cancer risk with the general population, we estimated country-, age-, and sex-specific standardized incidence ratios (SIRs) of cancer for carriers and noncarriers.

RESULTS

Over a median follow-up of 5 years, mutation carriers had an increased risk of colorectal cancer (CRC; SIR, 20.48; 95% CI, 11.71 to 33.27; P < .001), endometrial cancer (SIR, 30.62; 95% CI, 11.24 to 66.64; P < .001), ovarian cancer (SIR, 18.81; 95% CI, 3.88 to 54.95; P < .001), renal cancer (SIR, 11.22; 95% CI, 2.31 to 32.79; P < .001), pancreatic cancer (SIR, 10.68; 95% CI, 2.68 to 47.70; P = .001), gastric cancer (SIR, 9.78; 95% CI, 1.18 to 35.30; P = .009), urinary bladder cancer (SIR, 9.51; 95% CI, 1.15 to 34.37; P = .009), and female breast cancer (SIR, 3.95; 95% CI, 1.59 to 8.13; P = .001). We found no evidence of their noncarrier relatives having an increased risk of any cancer, including CRC (SIR, 1.02; 95% CI, 0.33 to 2.39; P = .97).

CONCLUSION

We confirmed that carriers of an MMR gene mutation were at increased risk of a wide variety of cancers, including some cancers not previously recognized as being a result of MMR mutations, and found no evidence of an increased risk of cancer for their noncarrier relatives.

Breast cancer risk for noncarriers of family-specific BRCA1 and BRCA2 mutations: findings from the Breast Cancer Family Registry

PURPOSE

Women with germline BRCA1 and BRCA2 mutations have five- to 20-fold increased risks of developing breast and ovarian cancer. A recent study claimed that women testing negative for their family-specific BRCA1 or BRCA2 mutation (noncarriers) have a five-fold increased risk of breast cancer. We estimated breast cancer risks for noncarriers by using a population-based sample of patients with breast cancer and their female first-degree relatives (FDRs).

PATIENTS AND METHODS

Patients were women with breast cancer and their FDRs enrolled in the population-based component of the Breast Cancer Family Registry; patients with breast cancer were tested for BRCA1 and BRCA2 mutations, as were FDRs of identified mutation carriers. We used segregation analysis to fit a model that accommodates familial correlation in breast cancer risk due to unobserved shared risk factors.

RESULTS

We studied 3,047 families; 160 had BRCA1 and 132 had BRCA2 mutations. There was no evidence of increased breast cancer risk for noncarriers of identified mutations compared with FDRs from families without BRCA1 or BRCA2 mutations: relative risk was 0.39 (95% CI, 0.04 to 3.81). Residual breast cancer correlation within families was strong, suggesting substantial risk heterogeneity in women without BRCA1 or BRCA2 mutations, with some 3.4% of them accounting for roughly one third of breast cancer cases.

CONCLUSION

These results support the practice of advising noncarriers that they do not have any increase in breast cancer risk attributable to the family-specific BRCA1 or BRCA2 mutation.

Prospective study of breast cancer risk for mutation negative women from BRCA1 or BRCA2 mutation positive families

Published studies have reached contradictory conclusions regarding breast cancer risk for women from families segregating a BRCA1 or BRCA2 mutation who do not carry the family-specific mutation. Accurate estimation of breast cancer risk is crucial for appropriate counselling regarding risk management. The aim of this study is to prospectively assess whether breast cancer risk for mutation negative women from families segregating BRCA1 or BRCA2 mutations is greater than for women in the general population. Eligible women were 722 first-, second- and third-degree relatives of a BRCA1 or BRCA2 mutation carrier from 224 mutation positive (128 BRCA1, 96 BRCA2) families, had no personal cancer history at baseline, and had been tested and found not to carry the family-specific mutation. Self-reported family history of cancer, preventive interventions and verified cancer diagnoses were collected at baseline, and every 3 years thereafter. Median follow-up was 6.1 years (range 0.1-12.4 years). Time at risk of breast cancer was censored at cancer diagnosis or risk-reducing surgery. Standardised incidence ratios (SIR) were estimated by comparing observed to population incidences of invasive breast cancer using Australian Cancer Incidence and Mortality Books. Six cases of invasive breast cancer were observed. The estimated SIRs were 1.14 (95% CI: 0.51-2.53) overall (n = 722), 1.29 (95% CI: 0.58-2.88) when restricted to first- and second-degree relatives of an affected mutation carrier (n = 442) and 0.48 (95% CI: 0.12-1.93) when restricted to those with no family history of breast cancer in the non-mutation carrying parental lineage (n = 424). There was no evidence that mutation negative women from families segregating BRCA1 or BRCA2 mutations are at increased risk of breast cancer. Despite this being the largest prospective cohort to assess this issue, moderately increased breast cancer risk (2-fold) cannot be ruled out.

Breast and ovarian cancer screening of non-carriers from BRCA1/2 mutation-positive families: 2-year follow-up of cohorts from France and Quebec

We described and compared breast and ovarian screening practices in the 2-year period following test result disclosure in female non-carriers from BRCA1/2 mutation-positive families living in two countries, France and Quebec, Canada, which provide universal health care. Four hundred and two (France n=293; Quebec n=109) unaffected female non-carriers from BRCA-proven mutation families provided information about the uptake of mammography, clinical breast examination, breast self-examination, and ovarian ultrasounds using self-administered questionnaires. The frequency of screening practices between study cohorts were compared using logistic regression. Annual mammography was conducted in 23 and 43% of French and Quebecer women participants <50 years of age, respectively (adjusted odds ratio (aOR)=2.72; 95% confidence interval (CI), 1.08-6.81). In women ≥ 50 years of age, mammography was conducted in 49 and 65% of French and Quebecer participants (aOR=1.77; 95% CI, 0.07-4.51). Overall, 33% of French women and 39% of Quebecer women underwent at least one ovarian ultrasound during the 2-year period following BRCA1/2 test result with no significant difference between cohorts of women < 50 years of age. Among older women, Quebecers reported more frequently than French women that they had undergone ultrasound once (aOR=3.00; 95% CI, 1.02-8.83). The frequency of cancer screening practices for female non-carriers from BRCA1/2 mutation-positive families in both France and Quebec exceeded those recommended for similarly aged women in the general population. Our findings highlight the need for clearcut recommendations on the follow-up of women from BRCA1/2 families who are not themselves carriers of a BRCA1/2 mutation.