Routine Tumor Testing for Homologous Recombination Deficiency in Patients With High Grade Epithelial Ovarian Cancer at a Statewide Gynecological Cancer Service in Western Australia: An Observational Study.

Background: Poly-ADP ribose polymerase inhibitors have been shown to improve progression-free survival in patients with advanced high-grade epithelial non-mucinous ovarian cancers characterized by a deficiency in homologous recombination (HRD). Guidelines recommend all patients with advanced high-grade epithelial ovarian cancer undergo genomic tumor testing for HRD. Our aim was to evaluate the first year of HRD testing at the statewide Western Australia Gynecologic Cancer Service to assess factors associated with obtaining a diagnostic HRD testing result.

Methods: Retrospective chart review.

Results: HRD testing was indicated in 84 patients, and ordered in 79, of which three had non-diagnostic/inconclusive results, all due to insufficient tumor quantity. One patient had the sample collected using a 20-gauge core biopsy needle under image guidance, one patient following interval debulking surgery, and one following primary debulking surgery. Of 76 patients with an HRD result, HRD was positive in 29 (38.2%). A somatic BRCA mutation was detected in six of these 29 patients (20.6%) and HRD positive, BRCAwt was detected in 23 of 29 patients (79.4%). All core biopsies with 16- and 18-gauge needles had a diagnostic HRD result. Ten of 11 patients who were treated by neoadjuvant chemotherapy and whose biopsies were obtained at interval cytoreductive surgery had sufficient tumor tissue for testing and had a diagnostic HRD result. All ascitic/pleural fluid samples sent for HRD testing yielded diagnostic results.

Conclusions: Compliance with HRD testing was high, and only three of 79 (3.8%) patients had non-diagnostic results.