UK consensus recommendations for clinical management of cancer risk for women with germline pathogenic variants in cancer predisposition genes: RAD51C, RAD51D, BRIP1 and PALB2

British Gynaecological Cancer Society/British Association of Gynaecological Pathology consensus for genetic testing in epithelial ovarian cancer in the United Kingdom

Standard of care genetic testing has undergone significant changes in recent years. The British Gynecological Cancer Society and the British Association of Gynecological Pathologists (BGCS/BAGP) has re-assembled a multidisciplinary expert consensus group to update the previous guidance with the latest standard of care for germline and tumor testing in patients with ovarian cancer. For the first time, the BGCS/BAGP guideline group has incorporated a patient advisor at the initial consensus group meeting. We have used patient focused groups to inform discussions related to reflex tumor testing - a key change in this updated guidance. This report summarizes recommendations from our consensus group deliberations and audit standards to support continual quality improvement in routine clinical settings.

Prevention, diagnosis and clinical management of hereditary breast cancer beyond BRCA1/2 genes

The detection of germline pathogenic variants (gPVs) in BRCA1/2 and other breast cancer (BC) genes is rising exponentially thanks to the advent of multi-gene panel testing. This promising technology, coupled with the availability of specific therapies for BC BRCA-related, has increased the number of patients eligible for genetic testing. Implementing multi-gene panel testing for hereditary BC screening holds promise to maximise benefits for patients at hereditary risk of BC. These benefits range from prevention programs to antineoplastic-targeted therapies. However, the clinical management of these patients is complex and requires guidelines based on recent evidence. Furthermore, applying multi-gene panel testing into clinical practice increases the detection of variants of uncertain significance (VUSs). This augments the complexity of patients' clinical management, becoming an unmet need for medical oncologists. This review aims to collect updated evidence on the most common BC-related genes besides BRCA1/2, from their biological role in BC development to their potential impact in tailoring prevention and treatment strategies.

Germline RAD51C and RAD51D Mutations in High-Risk Chinese Breast and/or Ovarian Cancer Patients and Families

BACKGROUND

RAD51C and RAD51D are crucial in homologous recombination (HR) DNA repair. The prevalence of the RAD51C and RAD51D mutations in breast cancer varies across ethnic groups. Associations of RAD51C and RAD51D germline pathogenic variants (GPVs) with breast and ovarian cancer predisposition have been recently reported and are of interest.

METHODS

We performed multi-gene panel sequencing to study the prevalence of RAD51C and RAD51D germline mutations among 3728 patients with hereditary breast and/or ovarian cancer (HBOC).

RESULTS

We identified 18 pathogenic RAD51C and RAD51D mutation carriers, with a mutation frequency of 0.13% (5/3728) and 0.35% (13/3728), respectively. The most common recurrent mutation was RAD51D c.270_271dupTA; p.(Lys91Ilefs*13), with a mutation frequency of 0.30% (11/3728), which was also commonly identified in Asians. Only four out of six cases (66.7%) of this common mutation tested positive for homologous recombination deficiency (HRD).

CONCLUSIONS

Taking the family studies in our registry and tumor molecular pathology together, we concluded that this relatively common RAD51D variant showed incomplete penetrance in our local Chinese community. Personalized genetic counseling emphasizing family history for families with this variant, as suggested at the UK Cancer Genetics Group (UKCGG) Consensus meeting, would also be appropriate in Chinese families.

Clinical Impact of Constitutional Genomic Testing on Current Breast Cancer Care

The most commonly diagnosed cancer in women worldwide is cancer of the breast. Up to 20% of familial cases are attributable to pathogenic mutations in high-penetrance (BReast CAncer gene 1 [BRCA1], BRCA2, tumor protein p53 [TP53], partner and localizer of breast cancer 2 [PALB2]) or moderate-penetrance (checkpoint kinase 2 [CHEK2], Ataxia-telangiectasia mutated [ATM], RAD51C, RAD51D) breast-cancer-predisposing genes. Most of the breast-cancer-predisposing genes are involved in DNA damage repair via homologous recombination pathways. Understanding these pathways can facilitate the development of risk-reducing and therapeutic strategies. The number of breast cancer patients undergoing testing for pathogenic mutations in these genes is rapidly increasing due to various factors. Advances in multigene panel testing have led to increased detection of pathogenic mutation carriers at high risk for developing breast cancer and contralateral breast cancer. However, the lack of long-term clinical outcome data and incomplete understanding of variants, particularly for moderate-risk genes limits clinical application. In this review, we have summarized the key functions, risks, and prognosis of breast-cancer-predisposing genes listed in the National Health Service (NHS) England National Genomic Test Directory for inherited breast cancer and provide an update on current management implications including surgery, radiotherapy, systemic treatments, and post-treatment surveillance.

Screening and Testing for Homologous Recombination Repair Deficiency (HRD) in Breast Cancer: an Overview of the Current Global Landscape

PURPOSE OF REVIEW

Homologous recombination repair deficiency (HRD) increases breast cancer susceptibility and influences both prophylactic and active management of breast cancer. This review evaluates HRD testing and the therapeutic implications of HRD in a global context.

RECENT FINDINGS

Ongoing research efforts have highlighted the importance of HRD beyond BRCA1/2 as a potential therapeutic target in breast cancer. However, despite the improved affordability of next-generation sequencing (NGS) and the discovery of PARP inhibitors, economic and geographical barriers in access to HRD testing and breast cancer screening do not allow all patients to benefit from the personalized treatment approach they provide. Advancements in HRD testing modalities and targeted therapeutics enable tailored breast cancer management. However, inequalities in access to testing and optimized treatments are contributing to widening health disparities globally.

Extended panel testing in ovarian cancer reveals BRIP1 as the third most important predisposition gene

PURPOSE

The prevalence of germline pathogenic variants (PVs) in homologous recombination repair (HRR) and Lynch syndrome (LS) genes in ovarian cancer (OC) is uncertain.

METHODS

An observational study reporting the detection rate of germline PVs in HRR and LS genes in all OC cases tested in the North West Genomic Laboratory Hub between September 1996 and May 2024. Effect sizes are reported using odds ratios (ORs) and 95% confidence intervals (95% CI) for unselected cases tested between April 2021 and May 2024 versus 50,703 controls from the Breast Cancer Risk after Diagnostic Gene Sequencing study.

RESULTS

2934 women were tested for BRCA1/2 and 433 (14.8%) had a PV. In up to 1572 women tested for PVs in non-BRCA1/2 HRR genes, detection rates were PALB2 = 0.8%, BRIP1 = 1.1%, RAD51C = 0.4% and RAD51D = 0.4%. In 940 unselected cases, BRIP1 (OR = 8.7, 95% CI 4.6-15.8) was the third most common OC predisposition gene followed by RAD51C (OR = 8.3, 95% CI 3.1-23.1), RAD51D (OR = 6.5, 95% CI 2.1-19.7), and PALB2 (OR = 3.9, 95% CI 1.5-10.3). No PVs in LS genes were detected in unselected cases.

CONCLUSION

Panel testing in OC resulted in a detection rate of 2% to 3% for germline PVs in non-BRCA1/2 HRR genes, with the largest contributor being BRIP1. Screening for LS in unselected cases of OC is unnecessary.

Extent of investigation and management of cases of 'unexplained' mismatch repair deficiency (u-dMMR): a UK Cancer Genetics Group consensus

BACKGROUND

Mismatch repair deficiency (dMMR) is a characteristic feature of cancers linked to Lynch syndrome. However, in most cases, it results from sporadic somatic events rather than hereditary factors. The term 'Lynch-like syndrome' (LLS) has been used to guide colorectal cancer surveillance for relatives of individuals with a dMMR tumour when somatic and germline genomic testing is uninformative. As the assessment of mismatch repair through immunohistochemistry and/or microsatellite instability is increasingly applied across various tumour types for treatment planning, dMMR is increasingly detected in tumours where suspicion of hereditary aetiology is low. Our objective was to establish current practices and develop national guidance for investigating, and managing relatives of, patients with cancers demonstrating unexplained dMMR.

METHODS

This was achieved through a virtual consensus meeting involving key stakeholders from the UK, through premeeting surveys, structured discussions and in-meeting polling to formulate best practice guidance.

RESULTS

We identified variability in the availability of diagnostic technologies across specialist centres. It was agreed that equitable access to baseline testing is required, acknowledging the need for a pragmatic approach to investigating dMMR cancers not traditionally associated with Lynch syndrome. Factors such as family history, age, tumour type, protein loss pattern and extent of the investigation were deemed crucial in guiding family management. The term 'unexplained dMMR' was recommended over LLS.

CONCLUSION

Decisions regarding investigations and future cancer risk management in patients and relatives should be nuanced, considering factors like clinical suspicion of hereditary predisposition to allocate limited resources efficiently and avoid unnecessary investigations in low-suspicion families.

Cascade screening in HBOC and Lynch syndrome: guidelines and procedures in a UK centre

In the 33 years since the first diagnostic cancer predisposition gene (CPG) tests in the Manchester Centre for Genomic Medicine, there has been substantial changes in the identification of index cases and cascade testing for at-risk family members. National guidelines in England and Wales are usually determined from the National Institute of healthcare Evidence and these have impacted on the thresholds for testing BRCA1/2 in Hereditary Breast Ovarian Cancer (HBOC) and in determining that all cases of colorectal and endometrial cancer should undergo screening for Lynch syndrome. Gaps for testing other CPGs relevant to HBOC have been filled by the UK Cancer Genetics Group and CanGene-CanVar project (web ref. https://www.cangene-canvaruk.org/ ). We present time trends (1990-2020) of identification of index cases with germline CPG variants and numbers of subsequent cascade tests, for BRCA1, BRCA2, and the Lynch genes (MLH1, MSH2, MSH6 and PMS2). For BRCA1/2 there was a definite increase in the proportion of index cases with ovarian cancer only and pre-symptomatic index tests both doubling from 16 to 32% and 3.2 to > 8% respectively. A mean of 1.73-1.74 additional family tests were generated for each BRCA1/2 index case within 2 years. Overall close to one positive cascade test was generated per index case resulting in > 1000 risk reducing surgery operations. In Lynch syndrome slightly more cascade tests were performed in the first two years potentially reflecting the increased actionability in males with 42.2% of pre-symptomatic tests in males compared to 25.8% in BRCA1/2 (p < 0.0001).

Utility Scores for Risk-Reducing Mastectomy and Risk-Reducing Salpingo-Oophorectomy: Mapping to EQ-5D

BACKGROUND

Risk-reducing mastectomy (RRM) and risk-reducing salpingo-oophorectomy (RRSO) are the most effective breast and ovarian cancer preventive interventions. EQ-5D is the recommended tool to assess the quality of life and determine health-related utility scores (HRUSs), yet there are no published EQ-5D HRUSs after these procedures. These are essential for clinicians counselling patients and for health-economic evaluations.

METHODS

We used aggregate data from our published systematic review and converted SF-36/SF-12 summary scores to EQ-5D HRUSs using a published mapping algorithm. Study control arm or age-matched country-specific reference values provided comparison. Random-effects meta-analysis provided adjusted disutilities and utility scores. Subgroup analyses included long-term vs. short-term follow-up.

RESULTS

Four studies (209 patients) reported RRM outcomes using SF-36, and five studies (742 patients) reported RRSO outcomes using SF-12/SF-36. RRM is associated with a long-term (>2 years) disutility of -0.08 (95% CI -0.11, -0.04) (I2 31.4%) and a utility of 0.92 (95% CI 0.88, 0.95) (I2 31.4%). RRSO is associated with a long-term (>1 year) disutility of -0.03 (95% CI -0.05, 0.00) (I2 17.2%) and a utility of 0.97 (95% CI 0.94, 0.99) (I2 34.0%).

CONCLUSIONS

We present the first HRUSs sourced from patients following RRM and RRSO. There is a need for high-quality prospective studies to characterise quality of life at different timepoints.

Screening and prevention of ovarian cancer

Ovarian cancer remains the most lethal gynaecological malignancy with 314 000 cases and 207 000 deaths annually worldwide. Ovarian cancer cases and deaths are predicted to increase in Australia by 42% and 55% respectively by 2040. Earlier detection and significant downstaging of ovarian cancer have been demonstrated with multimodal screening in the largest randomised controlled trial of ovarian cancer screening in women at average population risk. However, none of the randomised trials have demonstrated a mortality benefit. Therefore, ovarian cancer screening is not currently recommended in women at average population risk. More frequent surveillance for ovarian cancer every three to four months in women at high risk has shown good performance characteristics and significant downstaging, but there is no available information on a survival benefit. Population testing offers an emerging novel strategy to identify women at high risk who can benefit from ovarian cancer prevention. Novel multicancer early detection biomarker, longitudinal multiple marker strategies, and new biomarkers are being investigated and evaluated for ovarian cancer screening. Risk-reducing salpingo-oophorectomy (RRSO) decreases ovarian cancer incidence and mortality and is recommended for women at over a 4-5% lifetime risk of ovarian cancer. Pre-menopausal women without contraindications to hormone replacement therapy (HRT) undergoing RRSO should be offered HRT until 51 years of age to minimise the detrimental consequences of premature menopause. Currently risk-reducing early salpingectomy and delayed oophorectomy (RRESDO) should only be offered to women at increased risk of ovarian cancer within the context of a research trial. Pre-menopausal early salpingectomy is associated with fewer menopausal symptoms and better sexual function than bilateral salpingo-oophorectomy. A Sectioning and Extensively Examining the Fimbria (SEE-FIM) protocol should be used for histopathological assessment in women at high risk of ovarian cancer who are undergoing surgical prevention. Opportunistic salpingectomy may be offered at routine gynaecological surgery to all women who have completed their family. Long term prospective opportunistic salpingectomy studies are needed to determine the effect size of ovarian cancer risk reduction and the impact on menopause.

Cost-Effectiveness of Gene-Specific Prevention Strategies for Ovarian and Breast Cancer

Importance

Pathogenic variants (PVs) in BRCA1, BRCA2, PALB2, RAD51C, RAD51D, and BRIP1 cancer susceptibility genes (CSGs) confer an increased ovarian cancer (OC) risk, with BRCA1, BRCA2, PALB2, RAD51C, and RAD51D PVs also conferring an elevated breast cancer (BC) risk. Risk-reducing surgery, medical prevention, and BC surveillance offer the opportunity to prevent cancers and deaths, but their cost-effectiveness for individual CSGs remains poorly addressed.

Objective

To estimate the cost-effectiveness of prevention strategies for OC and BC among individuals carrying PVs in the previously listed CSGs.

Design, Setting, and Participants

In this economic evaluation, a decision-analytic Markov model evaluated the cost-effectiveness of risk-reducing salpingo-oophorectomy (RRSO) and, where relevant, risk-reducing mastectomy (RRM) compared with nonsurgical interventions (including BC surveillance and medical prevention for increased BC risk) from December 1, 2022, to August 31, 2023. The analysis took a UK payer perspective with a lifetime horizon. The simulated cohort consisted of women aged 30 years who carried BRCA1, BRCA2, PALB2, RAD51C, RAD51D, or BRIP1 PVs. Appropriate sensitivity and scenario analyses were performed.

Exposures

CSG-specific interventions, including RRSO at age 35 to 50 years with or without BC surveillance and medical prevention (ie, tamoxifen or anastrozole) from age 30 or 40 years, RRM at age 30 to 40 years, both RRSO and RRM, BC surveillance and medical prevention, or no intervention.

Main Outcomes and Measures

The incremental cost-effectiveness ratio (ICER) was calculated as incremental cost per quality-adjusted life-year (QALY) gained. OC and BC cases and deaths were estimated.

Results

In the simulated cohort of women aged 30 years with no cancer, undergoing both RRSO and RRM was most cost-effective for individuals carrying BRCA1 (RRM at age 30 years; RRSO at age 35 years), BRCA2 (RRM at age 35 years; RRSO at age 40 years), and PALB2 (RRM at age 40 years; RRSO at age 45 years) PVs. The corresponding ICERs were -£1942/QALY (-$2680/QALY), -£89/QALY (-$123/QALY), and £2381/QALY ($3286/QALY), respectively. RRSO at age 45 years was cost-effective for RAD51C, RAD51D, and BRIP1 PV carriers compared with nonsurgical strategies. The corresponding ICERs were £962/QALY ($1328/QALY), £771/QALY ($1064/QALY), and £2355/QALY ($3250/QALY), respectively. The most cost-effective preventive strategy per 1000 PV carriers could prevent 923 OC and BC cases and 302 deaths among those carrying BRCA1; 686 OC and BC cases and 170 deaths for BRCA2; 464 OC and BC cases and 130 deaths for PALB2; 102 OC cases and 64 deaths for RAD51C; 118 OC cases and 76 deaths for RAD51D; and 55 OC cases and 37 deaths for BRIP1. Probabilistic sensitivity analysis indicated both RRSO and RRM were most cost-effective in 96.5%, 89.2%, and 84.8% of simulations for BRCA1, BRCA2, and PALB2 PVs, respectively, while RRSO was cost-effective in approximately 100% of simulations for RAD51C, RAD51D, and BRIP1 PVs.

Conclusions and Relevance

In this cost-effectiveness study, RRSO with or without RRM at varying optimal ages was cost-effective compared with nonsurgical strategies for individuals who carried BRCA1, BRCA2, PALB2, RAD51C, RAD51D, or BRIP1 PVs. These findings support personalizing risk-reducing surgery and guideline recommendations for individual CSG-specific OC and BC risk management.

Co-design of patient information leaflets for germline predisposition to cancer: recommendations for clinical practice from the UK Cancer Genetics Group (UKCGG), Cancer Research UK (CRUK) funded CanGene-CanVar Programme and the Association of Genetic Nurse Counsellors (AGNC)

BACKGROUND

Testing for germline pathogenic variants (GPVs) in cancer predisposition genes is increasingly offered as part of routine care for patients with cancer. This is often urgent in oncology clinics due to potential implications on treatment and surgical decisions. This also allows identification of family members who should be offered predictive genetic testing. In the UK, it is common practice for healthcare professionals to provide a patient information leaflet (PIL) at point of care for diagnostic genetic testing in patients with cancer, after results disclosure when a GPV is identified, and for predictive testing of at-risk relatives. Services usually create their own PIL, resulting in duplication of effort and wide variability regarding format, content, signposting and patient input in co-design and evaluation.

METHODS

Representatives from UK Cancer Genetics Group (UKCGG), Cancer Research UK (CRUK) funded CanGene-CanVar programme and Association of Genetic Nurse Counsellors (AGNC) held a 2-day meeting with the aim of making recommendations for clinical practice regarding co-design of PIL for germline cancer susceptibility genetic testing. Lynch syndrome and haematological malignancies were chosen as exemplar conditions.

RESULTS

Meeting participants included patient representatives including as co-chair, multidisciplinary clinicians and other experts from across the UK. High-level consensus for UK recommendations for clinical practice was reached on several aspects of PIL using digital polling, including that PIL should be offered, accessible, co-designed and evaluated with patients.

CONCLUSIONS

Recommendations from the meeting are likely to be applicable for PIL co-design for a wide range of germline genetic testing scenarios.

A comprehensive analysis of Fanconi anemia genes in Chinese patients with high-risk hereditary breast cancer

BACKGROUND

Four Fanconi anemia (FA) genes (BRCA1, BRCA2, PALB2 and RAD51C) are defined as breast cancer (BC) susceptibility genes. Other FA genes have been inconsistently associated with BC. Thus, the role of other FA genes in BC should be explored in specific populations.

METHODS

Mutations in 16 FA genes were screened with a 98-gene panel sequencing assay in a cohort of 1481 Chinese patients with high-risk hereditary BC. The association between mutations and clinicopathological characteristics as well as prognosis was analyzed. The risk of BC in carriers of FA gene mutations was assessed in the Genome Aggregation Database and the Westlake Biobank for Chinese cohort.

RESULTS

A total of 2.57% (38/1481) BC patients were identified who had 12 other FA gene germline mutations. Among them, the most frequently mutated gene was FANCA (8/1481, 0.54%). These 38 patients carried 35 distinct pathogenic/likely pathogenic variants, of which 21 were novel. We found one rare FANCB deleterious variant (c.1327-3dupT) in our cohort. There was a statistically significant difference in lymph node status between FA gene mutation carriers and non-carriers (p = 0.041). We observed a trend that mutation carriers had larger tumor sizes, lower estrogen receptor (ER) and progesterone receptor (PR) positivity rates, and lower 3.5-year invasive disease-free survival (iDFS) and distant recurrence-free survival (DRFS) rates than non-carriers (tumor size > 2 cm: 51.43% vs. 45.63%; ER positivity rates: 51.43% vs. 60.81%; PR positivity rates: 48.57% vs. 55.16%; 3.5-year iDFS rates: 58.8% vs. 66.7%; 3.5-year DRFS rates: 58.8% vs. 68.8%). The frequency of the mutations in FANCD2, FANCM and BRIP1 trended to be higher among BC cases than that in controls (p = 0.055, 0.08 and 0.08, respectively).

CONCLUSION

This study comprehensively estimated the prevalence, clinicopathological characteristics, prognosis and risk of BC associated with deleterious variants in FA genes in Chinese high-risk hereditary BC patients. It enriches our understanding of the role of FA genes with BC.

Quality of life after risk-reducing surgery for breast and ovarian cancer prevention: a systematic review and meta-analysis

OBJECTIVE

This study aimed to assess the impact of risk-reducing surgery for breast cancer and ovarian cancer prevention on quality of life. We considered risk-reducing mastectomy, risk-reducing salpingo-oophorectomy, and risk-reducing early salpingectomy and delayed oophorectomy.

DATA SOURCES

We followed a prospective protocol (International Prospective Register of Systematic Reviews: CRD42022319782) and searched MEDLINE, Embase, PubMed, and Cochrane Library from inception to February 2023.

STUDY ELIGIBILITY CRITERIA

We followed a PICOS (population, intervention, comparison, outcome, and study design) framework. The population included women at increased risk of breast cancer or ovarian cancer. We focused on studies reporting quality of life outcomes (health-related quality of life, sexual function, menopause symptoms, body image, cancer-related distress or worry, anxiety, or depression) after risk-reducing surgery, including risk-reducing mastectomy for breast cancer and risk-reducing salpingo-oophorectomy or risk-reducing early salpingectomy and delayed oophorectomy for ovarian cancer.

METHODS

We used the Methodological Index for Non-Randomized Studies (MINORS) for study appraisal. Qualitative synthesis and fixed-effects meta-analysis were performed.

RESULTS

A total of 34 studies were included (risk-reducing mastectomy: 16 studies; risk-reducing salpingo-oophorectomy: 19 studies; risk-reducing early salpingectomy and delayed oophorectomy: 2 studies). Health-related quality of life was unchanged or improved in 13 of 15 studies after risk-reducing mastectomy (N=986) and 10 of 16 studies after risk-reducing salpingo-oophorectomy (N=1617), despite short-term deficits (N=96 after risk-reducing mastectomy and N=459 after risk-reducing salpingo-oophorectomy). Sexual function (using the Sexual Activity Questionnaire) was affected in 13 of 16 studies (N=1400) after risk-reducing salpingo-oophorectomy in terms of decreased sexual pleasure (-1.21 [-1.53 to -0.89]; N=3070) and increased sexual discomfort (1.12 [0.93-1.31]; N=1400). Hormone replacement therapy after premenopausal risk-reducing salpingo-oophorectomy was associated with an increase (1.16 [0.17-2.15]; N=291) in sexual pleasure and a decrease (-1.20 [-1.75 to -0.65]; N=157) in sexual discomfort. Sexual function was affected in 4 of 13 studies (N=147) after risk-reducing mastectomy, but stable in 9 of 13 studies (N=799). Body image was unaffected in 7 of 13 studies (N=605) after risk-reducing mastectomy, whereas 6 of 13 studies (N=391) reported worsening. Increased menopause symptoms were reported in 12 of 13 studies (N=1759) after risk-reducing salpingo-oophorectomy with a reduction (-1.96 [-2.81 to -1.10]; N=1745) in the Functional Assessment of Cancer Therapy - Endocrine Symptoms. Cancer-related distress was unchanged or decreased in 5 of 5 studies after risk-reducing mastectomy (N=365) and 8 of 10 studies after risk-reducing salpingo-oophorectomy (N=1223). Risk-reducing early salpingectomy and delayed oophorectomy (2 studies, N=413) led to better sexual function and menopause-specific quality of life.

CONCLUSION

Risk-reducing surgery may be associated with quality of life outcomes. Risk-reducing mastectomy and risk-reducing salpingo-oophorectomy reduce cancer-related distress, and do not affect health-related quality of life. Women and clinicians should be aware of body image problems after risk-reducing mastectomy, and of sexual dysfunction and menopause symptoms after risk-reducing salpingo-oophorectomy. Risk-reducing early salpingectomy and delayed oophorectomy may be a promising alternative to mitigate quality of life-related risks of risk-reducing salpingo-oophorectomy.

The APOBEC3B c.783delG Truncating Mutation Is Not Associated with an Increased Risk of Breast Cancer in the Polish Population

The APOBEC3B gene belongs to a cluster of DNA-editing enzymes on chromosome 22 and encodes an activation-induced cytidine deaminase. A large deletion of APOBEC3B was associated with increased breast cancer risk, but the evidence is inconclusive. To investigate whether or not APOBEC3B is a breast cancer susceptibility gene, we sequenced this gene in 617 Polish patients with hereditary breast cancer. We detected a single recurrent truncating mutation (c.783delG, p.Val262Phefs) in four of the 617 (0.65%) hereditary cases by sequencing. We then genotyped an additional 12,484 women with unselected breast cancer and 3740 cancer-free women for the c.783delG mutation. The APOBEC3B c.783delG allele was detected in 60 (0.48%) unselected cases and 19 (0.51%) controls (OR = 0.95, 95% CI 0.56-1.59, p = 0.94). The allele was present in 8 of 1968 (0.41%) familial breast cancer patients from unselected cases (OR = 0.80, 95% CI 0.35-1.83, p = 0.74). Clinical characteristics of breast tumors in carriers of the APOBEC3B mutation and non-carriers were similar. No cancer type was more frequent in the relatives of mutation carriers than in those of non-carriers. We conclude the APOBEC3B deleterious mutation p.Val262Phefs does not confer breast cancer risk. These data do not support the hypothesis that APOBEC3B is a breast cancer susceptibility gene.