90 Background: Germline and somatic alterations in genes associated with DNA repair are common in patients with mPCa and have treatment implications. International guidelines uniformly recommend genomic testing for patients with mPCa however a variety of barriers influence uptake. In the Canadian province of British Columbia (population 5.7 million), publicly funded tumor and germline centralized genomic testing became available for all patients with mPCa in May 2022. We reviewed the program to understand uptake, utilization, clinical impact and identify areas for improvement. Methods: This multicenter, retrospective observational study included all patients in British Columbia with mPCa who underwent molecular tumor testing at the Cancer Genetics and Genomics Laboratory (CGL) of BC Cancer from initiation of the program on 24 May 2022 to 24 May 2024. Tumor tissue testing was prioritized with blood based circulating tumor DNA (ctDNA) serving as an alternative where tumor tissue testing failed or was not possible. Data were extracted from the CGL database and electronic medical records, and analysed using descriptive statistics. Results: Over the two-year period, 2119 individual patients underwent a total of 2253 tests; 2018 tissue tests and 235 ctDNA tests. Most tests (83.0%) were requested by medical oncologists. Median turnaround times from receipt of tissue by the laboratory to result date were 31 days, 44 days, and 66 days for ctDNA, tissue and germline tests, respectively. 235 (11.6%) tissue tests failed, and 153 (65.1%) ctDNA tests had undetectable ctDNA. An estimated 113 (73.9%) of the ctDNA tests with undetectable ctDNA could potentially have been avoided by limiting testing to patients with: 1) metastatic hormone-sensitive prostate cancer on androgen deprivation ≤14 days (46 avoidable tests), and 2) progressive metastatic castration-resistant prostate cancer with a predicted ctDNA fraction of ≥2% using the ctDNA.org tool (67 avoidable tests). Of 96 (4.5%) patients with a BRCA1/2 alteration detected, 47.9% received targeted PARP inhibitor treatment by February 2025, with a further 34.3% remaining eligible while responding to their current treatment. Conclusions: Population-wide tumor testing was rapidly adopted in British Columbia, resulting in identification of actionable alterations and facilitating access to targeted therapies in keeping with international guidelines. Education on optimal timing for cfDNA collection is needed to reduce unnecessary testing and improve test yield.
Roberts et al. (Sun,) studied this question.