Under-ascertainment of breast cancer susceptibility gene carriers in a cohort of New Zealand female breast cancer patients.

BACKGROUND: Diagnostic screening for pathogenic variants in breast cancer susceptibility genes, including BRCA1, BRCA2, PALB2, PTEN and TP53, may be offered to New Zealanders from suspected high-risk breast (and ovarian) cancer families. However, it is unknown how many high-risk pathogenic variant carriers in New Zealand are not offered genetic screening using existing triage tools and guidelines for breast (and ovarian) cancer patients. METHODS: Panel-gene sequencing of the coding and non-coding regions of the BRCA1 and BRCA2 genes, and the coding regions and splice sites of CDH1, PALB2, PTEN and TP53, was undertaken for an unselected cohort of 367 female breast cancer patients. A total of 1685 variants were evaluated using the ENIGMA and the ACMG/AMP variant classification guidelines. RESULTS: Our study identified that 13 (3.5%) breast cancer patients carried a pathogenic or likely pathogenic variant in BRCA1, BRCA2, PALB2, or PTEN. A significantly higher number of pathogenic variant carriers had grade 3 tumours (10/13) when compared to non-carriers; however, no other clinicopathological characteristics were found to be significantly different between (likely) pathogenic variant carriers and non-carriers, nor between variant of unknown significance carriers and non-carriers. Notably, 46% of the identified (likely) pathogenic variant carriers had not been referred for a genetic assessment and consideration of genetic testing. CONCLUSION: Our study shows a potential under-ascertainment of women carrying a (likely) pathogenic variant in a high-risk breast cancer susceptibility gene. These results suggest that further research into testing pathways for New Zealand breast cancer patients may be required to reduce the impact of hereditary cancer syndromes for these individuals and their families.

Ten-Year Follow-Up of Women at High Risk for Familial Breast and Ovarian Cancer in Otago and Southland, New Zealand.

BACKGROUND: Care for families affected by Familial Breast and Ovarian Cancer (FBOC) is challenging as a broad range of professions and specialties are involved. The aim was to review management and outcomes for a cohort of women at high risk for familial breast and ovarian cancer. METHODS: Ten-year retrospective follow-up study of individuals in Southern New Zealand  assessed by Genetic Health Service New Zealand to be high risk for FBOC and without a personal cancer diagnosis at time of consultation. RESULTS: Twenty women were identified; twelve underwent genetic testing, and a pathogenic BRCA variant was identified in eleven. Eight women had no testing, as no index case was available. Guidelines had been fully adhered to in 55% of women, regardless of BRCA status. Six did not undergo appropriate breast surveillance. To date, seven of the 11 patients who tested positive for a pathogenic BRCA variant (64%) had risk-reducing surgeries. Two women were diagnosed with breast cancer on surveillance imaging; none were diagnosed with ovarian cancer. Four women were lost to follow-up, one of whom subsequently presented with a symptomatic breast cancer. CONCLUSIONS: To our knowledge, this is the first study providing long-term data for FBOC in New Zealand. Overall, guidelines were followed satisfactorily, but some women did not receive appropriate surveillance or referrals. An integrated interdisciplinary long-term care provision model in New Zealand might help to address gaps in FBOC surveillance and management.