Background: The availability and affordability of germline genetic testing (GGT) has resulted in a broader utilization in daily clinical practice. However, adherence to testing guidelines is low, especially among older patients, where testing is often not offered.
Methods: In this study, consecutive, newly diagnosed patients with breast cancer (BC) aged ≥ 65 years and eligible for GGT, as per the National Comprehensive Cancer Network (NCCN) guidelines (version 1, 2021), were invited to participate, from March 2021 to December 2022. Patients were offered a restricted (two- or 20-gene panel), or an expanded 84-gene panel.
Results: During the study period, 204 patients were enrolled. The mean (standard deviation (SD)) age at BC diagnosis was 70.5 (5.13) years, ranging 65 - 81 years. All patients were Arab and the majority were Jordanian. The majority (n = 188, 92.2%) had early-stage (stages I and II) disease. One hundred three (50.5%) patients were tested with a restricted two-gene (n = 13) or 20-gene (n = 90) panel, while the remaining 101 (49.5%) patients had an expanded 84-gene panel. Family history of close blood relative(s) with BC was the most common indication for testing (n = 110, 53.9%). Among the entire study cohort, 22 (10.8%) had pathogenic/likely pathogenic germline variants (PGVs) and another 97 (47.5%) had ≥ 1 variants of uncertain significance (VUS). PGV rates were significantly higher with the expanded panel (14.9%) compared to restricted testing (6.8%) (P = 0.032). Similarly, VUS rates were significantly higher with the expanded panel (64.4%) compared to the restricted panel (31.1%) (P < 0.001). The most prevalent genes with PGVs were BRCA1/2 (31.3% of all PGV-positive patients), CHEK2 (23.1%) and ATM (19.2%).
Conclusion: GGT should not be overlooked in older BC patients, as this study demonstrates that > 10% of patients have PGVs, largely in potentially actionable genes.
Keywords: Breast cancer; Germline genetic testing; Older patients; Predisposition genes.
Copyright 2024, Abdel-Razeq et al.