Homologous recombination repair and breast cancer gene testing in prostate cancer: expert perspectives and practical guidance on best practice from sample acquisition to biomarker-informed clinical decision-making.

The prostate cancer (PCa) treatment landscape, particularly metastatic PCa, is rapidly evolving, with an increase in personalised treatment approaches and therapy selection being guided by tumour genomics. However, PCa remains the third leading cause of death among male-specific cancers in the European Union. Nearly a quarter of patients with metastatic PCa harbour homologous recombination repair (HRR) pathway mutations, with approximately 12% harbouring alterations in the BRCA1 or BRCA2 genes. These genomic alterations are associated with poorer prognosis and increased sensitivity to targeted therapies, such as poly(adenosine diphosphate-ribose) polymerase inhibitors. There is an urgent need to implement HRR and BRCA testing early in the treatment pathway. Despite treatment advances, early testing is not routinely implemented in clinical practice. Barriers include unequal testing access, a lack of clarity on who, when, and how to test, and how to interpret test results accurately. These may prevent eligible patients from receiving treatment early. To address this, we combine our clinical experience with the current literature to support the wider adoption of HRR/BRCA testing by providing practical recommendations for implementing best practices along the PCa molecular testing pathway. Our recommendations aim to help identify suitable patients for early testing and guide how to obtain, interpret, and utilise molecular test results in clinical decision-making.