When to Consider Risk-Reducing Mastectomy in BRCA1/BRCA2 Mutation Carriers with Advanced Stage Ovarian Cancer: a Case Study Illustrating the Genetic Counseling Challenges

Is There a Role for Risk-Reducing Bilateral Breast Surgery in BRCA1/2 Ovarian Cancer Survivors? An Observational Study

BACKGROUND

Risk-reducing surgeries are an option for cancer risk management in BRCA1/2 individuals. However, while adnexectomy is commonly recommended in breast cancer (BC) survivors, risk-reducing bilateral breast surgery (RRBBS) is controversial in ovarian cancer (OC) survivors due to relapse rates and mortality.

METHODS

We conducted a retrospective analysis of BRCA1/2-OC survivors, with OC as first cancer diagnosis.

RESULTS

Median age at OC diagnosis for the 69 BRCA1/2-OC survivors was 54 years. Median overall survival was 8 years, being significantly higher for BRCA2 patients than for BRCA1 patients (p = 0.011). Nine patients (13.2%) developed BC at a median age of 61 years. The mean overall BC-free survival was 15.5 years (median not reached). Eight patients (11.8%) underwent bilateral mastectomy (5 simultaneous with BC treatment; 3 RRBBS) at a median age of 56.5 years. The median time from OC to bilateral mastectomy/RRBBS was 5.5 years.

CONCLUSIONS

This study adds evidence regarding a lower BC risk after BRCA1/2-OC and higher survival for BRCA2-OC patients. A comprehensive analysis of the competing risks of OC mortality and recurrence against the risk of BC should be individually addressed. Surgical BC risk management may be considered for longer BRCA1/2-OC disease-free survivors. Ultimately, these decisions should always be tailored to patients' characteristics and preferences.

Low-level constitutional mosaicism of BRCA1 in two women with young onset ovarian cancer

Germline pathogenic variants in BRCA1 and BRCA2 cause hereditary breast and ovarian cancer. The vast majority of these variants are inherited from a parent. De novo constitutional pathogenic variants are rare. Even fewer cases of constitutional mosaicism have been reported and these have mostly been described in women with breast cancer. Here we report low-level constitutional mosaicism identified by Next Generation Sequencing in two women with ovarian cancer. A BRCA1 c.5074G > A p.(Asp1692Asn) variant detected in the first female at 42 years, classed as likely pathogenic, was found in ~ 52% of reads in DNA extracted from tumour, ~ 10% of reads in DNA extracted from peripheral blood leukocytes and ~ 10% of reads in DNA extracted from buccal mucosa. The second BRCA1 c.2755_2758dupCCTG p.(Val920AlafsTer6) variant was detected in a female aged 53 years, classed as pathogenic, and was found in ~ 59% of reads in DNA extracted from tumour, ~ 14% of reads in DNA extracted from peripheral blood leukocytes and similarly in ~ 14% of reads in both DNA extracted from buccal mucosa and urine sample. Sanger sequencing confirmed the presence of these variants at a corresponding low level consistent with mosaicism that may not have been detected by this method alone. This report demonstrates the clinical benefit for two women of BRCA1/BRCA2 germline NGS testing at a depth that can detect low-level mosaicism. As well as informing appropriate treatments, tumour sequencing results may facilitate the detection and interpretation of low-level mosaic variants in the germline. Both results have implications for other cancer risks and for relatives when providing a family cancer risk assessment and reproductive risk. The implications for laboratory practice, clinical genetics management and genetic counselling for constitutional mosaicism of BRCA1/BRCA2 are discussed.

Multidisciplinary interventions in a specialist Drug Development Unit to improve family history documentation and onward referral of patients with advanced cancer to cancer genetics services

BACKGROUND

Molecular aberrations in cancer may represent therapeutic targets, and, if arising from the germline, may impact further cancer risk management in patients and their blood relatives. Annually, 600-700 patients are referred for consideration of experimental drug trials in the Drug Development Unit (DDU) in our institution. A proportion of patients may merit germline genetic testing because of suspicious personal/family history or findings of tumour-based testing. We aimed to assess the impact of different multidisciplinary interventions on family history taking and referral rates from DDU to Cancer Genetics Unit (CGU).

METHODS

Over 42 months, three interventions were undertaken at different intervals: (1) embedding a genetics provider in the DDU review clinic, (2) 'traffic light' system flagging cancers with a heritable component and (3) virtual multidisciplinary meeting (MDM). Comparative analyses between intervals were undertaken, including referral rates to CGU, investigations and patient outcomes. Family history taking in a sample of 20 patients managed in each interval was assessed by a retrospective chart review.

RESULTS

Frequency of family history taking and referral to CGU, increased with each intervention, particularly, the virtual MDM (40% vs 85%). Referral rates increased over the study period, from 0.1 referral/week (5/year, 0.36% total referrals) to 1.2/week (projected 63/year, 3.81%). Forty-four (52%) patients referred required germline testing; in three of whom, variants were identified. Non-attendance rates were low (6, 7%).

CONCLUSION

Patients in the DDU are unique, with long cancer histories and often short estimated life expectancy. Multidisciplinary working between CGU and DDU facilitates germline testing of those patients who may otherwise miss the opportunity.