Comprehensive Genomic Profiling Testing for Castration-Resistant Prostate Cancer in Advanced Elderly Patients: A Single-Center Retrospective Cohort Study.

[BACKGROUND] Prostate cancer (PCa) is the second most common solid tumor in men, and its incidence is strongly dependent on age. With the aging global population, this poses a significant medical and sociodemographic issue. As treatment options for castration-resistant prostate cancer (CRPC) expand, the proportion of elderly patients with CRPC is expected to increase. Comprehensive genomic profiling (CGP) testing is becoming increasingly utilized for PCa; however, evidence on age-related outcomes or benefits is limited. This study aimed to evaluate the efficacy of CGP testing in advanced elderly patients with CRPC compared to younger patients.

[METHODS] We conducted a single-center, retrospective cohort study at Hiroshima University, including Japanese men aged ≥ 20 years who underwent CGP testing for CRPC between January 1, 2021, and May 31, 2024. Patients were categorized into the following two groups: the "advanced elderly group" (≥ 75 years) and the "younger group" (< 75 years). Clinical data were retrospectively extracted from medical records. CGP testing was performed using the FoundationOne® CDx, FoundationOne® Liquid CDx, Gurdant360® CDx, PleSSision Exome, or OncoGuide™ NCC Oncopanel System. Pathogenic alterations were categorized into relevant subgroups. Statistical analyzes were performed to compare patient backgrounds, genomic subgroups, and outcomes between the age groups.

[RESULTS] Overall, 85 patients (median age: 74 years) were included in the analysis, with 38 and 47 in the advanced elderly and younger groups, respectively. No significant differences were observed in baseline clinical characteristics other than age. CGP testing identified 355 pathogenic variants (140 and 215 in the advanced elderly and younger groups, respectively), with similar distributions of alteration types across the two groups. Among the subgroups, DNA repair and homologous recombination repair-related gene alterations were significantly more frequent in the younger group (p = 0.017) than in the advanced elderly group. Overall survival (OS) did not differ significantly between the age groups. However, patients who received systemic chemotherapy based on CGP testing results had significantly better OS than those who did not receive systemic therapy (p = 0.045). This trend remained significant in the advanced elderly group (p = 0.006).

[CONCLUSIONS] CGP testing appears to offer clinical benefits for patients with CRPC, regardless of age.