Uptake of BRCA1/BRCA2 predictive genetic testing in an Irish population is low: a missed opportunity.

INTRODUCTION: Predictive testing for BRCA1 or BRCA2 allows at-risk individuals to engage with appropriate screening and treatment services if a pathogenic mutation is identified. Previous studies have shown uptake of predictive testing to most commonly range between 20% and 40% (Table 2). This represents a missed cancer prevention opportunity. Possible explanations for this low uptake include lack of disclosure of at-risk status to relatives, lack of awareness of cancer genetics services, or patient preference. The goal of the current study was to investigate the uptake of BRCA1 or BRCA2 predictive testing in an Irish population. METHODS: We performed a multicentre, retrospective analysis of 63 pedigrees from two Irish tertiary referral hospitals over a five-year period (2012-2017). Family pedigrees were reviewed to identify at-risk family members eligible for predictive BRCA1 or BRCA2 mutation testing as per international guidelines, and testing rates were determined. RESULTS: A total of 1048 eligible individuals were identified, 318 (30.4%) proceeded to BRCA1 or BRCA2 germline testing including [215 (37.5%) females and 99 males (21.5%)]. Women were significantly more likely to test than men (T = 3.7, p < .0002). Uptake of testing was significant higher amongst first-degree relatives 45% (150/323) compared to 20% (50/258) amongst second degree relatives, and 10 % (33/317) amongst more distant relatives (F = 25.32, p < 0.00001). CONCLUSIONS: Uptake of BRCA1 OR BRCA2 mutation testing in Ireland is suboptimal, particularly amongst Irish males and distant relatives. Further research is needed to identify strategies which may improve uptake within current legal and ethical frameworks.

The contribution of Lynch syndrome to early onset malignancy in Ireland.

BACKGROUND: Lynch syndrome (LS) is an autosomal dominant hereditary cancer syndrome responsible for 2-4% of hereditary colorectal cancers (CRC). Mismatch repair protein deficiency (dMMR) is a characteristic feature of LS. It has been associated with a poor response to standard chemotherapy in metastatic colorectal cancer (mCRC). There is currently no LS database to monitor trends of disease in Ireland. We aim to centralise LS data in Ireland to assess the burden of LS in Ireland and guide improvements in prevention and treatment of LS-associated cancer. METHODS: A retrospective review was carried out including all medical records for LS patients from two of the three cancer genetics clinics in Ireland between 2000 and 2018 was carried out. Clinicopathological data of probands (n = 57) and affected family members including demographics, mutation status, cancer diagnosis and outcome was recorded. Statistical analysis was carried out using SPSS software. RESULTS: Fifty-seven families including three-hundred and forty-five individuals affected by cancer were identified. The most common cancers recorded were colorectal (53%), breast (12%) and endometrial (10%). One-hundred and thirty-eight confirmed carriers were identified: 65 path_MLH1 (47%), 43 path_MSH2 (31%), 11 path_MSH6 (8%), 17 path_PMS2 (12%) and two path_EPCAM (1%). Cancer type varied significantly by gene. Median age of first diagnosis was 44.5 years (range 23-81). Half of all deceased patients (n = 11) in this group died within 2.5 years of first diagnosis. These deaths were directly related to cancer in 59% of cases. CONCLUSIONS: Under diagnosis of LS misses a powerful preventive and therapeutic opportunity. LS causes early onset dMMR cancer diagnoses with substantial societal impact. Implementation of ICBs into treatment policy for this small cohort of dMMR mCRC is an achievable therapeutic goal that may significantly improve survival. A prospective database for LS in Ireland is necessary to maximise prevention in this population.

Prevalence of pancreaticobiliary cancers in Irish families with pathogenic BRCA1 and BRCA2 variants.

Pathogenic variants (PVs) in the BRCA1 and BRCA2 genes are associated with an increased lifetime risk of pancreatic ductal adenocarcinoma (PDAC), and more recently have been associated with increased risk of biliary tract cancers (BTC). This study assessed the prevalence, age and gender distribution of PDAC/BTC cases in families known to carry a BRCA1/2 PV compared to those of the Irish population. A review of all families referred to a national genetics clinic from 09/11/1997 to 01/06/2018 was performed. The BOADICEA algorithm was used to estimate the probability that an untested relative of a known BRCA1/2 PV carrier with PDAC was a carrier. We reviewed 3252 family pedigrees, 1193 contained a proband who underwent testing for BRCA1/2 based on Manchester score ≥ 15. Among 128 BRCA2 PV-positive families, 27 (21%) contained a 1st/2nd/3rd-degree relative with PDAC, while of 116 BRCA1 PV-positive families, 11 (9%) contained a 1st/2nd/3rd-degree relative with PDAC. Within these 38 families, 25 patients with PDAC had ≥ 50% likelihood of being a BRCA1/2 PV carrier. This cohort had a median age at diagnosis of 55 years (range 33-75), with a mean (55 years) lower than 8364 patients with PDAC identified through the National Cancer Registry of Ireland (71 years, p < 0.0001). Six BRCA2 positive (5%) and 2 BRCA1 positive pedigrees (2%) included an individual with BTC; median age at diagnosis was 65 years (range 33-99). PDAC and BTC are prevalent in Irish families harbouring a BRCA2 PV and are associated with early-onset malignancy. This supports current guidelines recommending universal germline testing for PDAC patients.

Clinical correlation and molecular evaluation confirm that the MLH1 p.Arg182Gly (c.544A>G) mutation is pathogenic and causes Lynch syndrome.

Approximately 25 % of mismatch repair (MMR) variants are exonic nucleotide substitutions. Some result in the substitution of one amino acid for another in the protein sequence, so-called missense variants, while others are silent. The interpretation of the effect of missense and silent variants as deleterious or neutral is challenging. Pre-symptomatic testing for clinical use is not recommended for relatives of individuals with variants classified as 'of uncertain significance'. These relatives, including non-carriers, are considered at high-risk as long as the contribution of the variant to disease causation cannot be determined. This results in continuing anxiety, and the application of potentially unnecessary screening and prophylactic interventions. We encountered a large Irish Lynch syndrome kindred that carries the c.544A>G (p.Arg182Gly) alteration in the MLH1 gene and we undertook to study the variant. The clinical significance of the variant remains unresolved in the literature. Data are presented on cancer incidence within five kindreds with the same germline missense variant in the MLH1 MMR gene. Extensive testing of relevant family members in one kindred, a review of the literature, review of online MMR mutation databases and use of in silico phenotype prediction tools were undertaken to study the significance of this variant. Clinical, histological, immunohistochemical and molecular evidence from these families and other independent clinical and scientific evidence indicates that the MLH1 p.Arg182Gly (c.544A>G) change causes Lynch syndrome and supports reclassification of the variant as pathogenic.

Surgical management of an Irish cohort of BRCA-mutation carriers.

Little information is available regarding the management of BRCA-related breast cancer in Ireland. A cancer genetics programme was initiated in 1992 at our institution to provide counselling and expert management for those with cancers resulting from inherited predisposition. We examined a cohort of BRCA mutation-carriers treated at a single institution over 16 years. A total of 107 women from 57 families were found to be carriers of mutations in BRCA1/2. Bilateral salpingo-oophorectomy was the most common prophylactic surgery performed. Overall survival between BRCA-related and sporadic breast cancer was equivalent. This is the first publication on surgical management of BRCA-mutation carriers in Ireland. It is imperative that those considered likely to harbour a mutation are referred early to a dedicated clinic so that appropriate counselling, testing and subsequent management to reduce the risk of dying from cancer can be undertaken.