# Barriers and Breakthroughs in Precision Oncology: A National Registry Study of BRCA Testing and PARP Inhibitor Uptake in Women from the National Gynae-Oncology Registry (NGOR)

## TL;DR

This study examines BRCA testing and PARP inhibitor use in Australian women with ovarian cancer, finding disparities in testing rates and treatment uptake.

## Contribution

The study provides national insights into BRCA testing and PARP inhibitor use in ovarian cancer care, identifying equity gaps and evidence-practice gaps.

## Key findings

- Germline and somatic BRCA testing rates were 68% and 32%, with higher rates in high-grade serous ovarian cancer.
- Older women and regional patients had lower testing rates, and only 52% of eligible patients started PARP inhibitor therapy.
- Somatic testing increased after public reimbursement for PARP inhibitors, indicating policy impact.

## Abstract

The identification of pathogenic variants in BRCA1 and BRCA2 is a critical predictive biomarker for the use of PARP inhibitors in women with epithelial ovarian cancer. However, real-world data on the uptake of BRCA testing and subsequent biomarker-driven therapy in Australia are not well characterised. This study leverages data from the Australian National Gynae-Oncology Registry (NGOR) to define national rates of germline and somatic BRCA testing and PARP inhibitor utilisation and to identify clinical and demographic determinants associated with these practices. Our findings reveal that while testing rates are encouraging compared to international benchmarks, significant disparities exist for older women (>80) and regional patient populations. Furthermore, a noteworthy evidence–practice gap was observed between the identification of a BRCA pathogenic variant and the initiation of PARP inhibitor therapy. These findings highlight where targeted health service interventions are needed to ensure all Australian women have equitable access to precision oncology.

Background: The identification of pathogenic variants in the Breast Cancer Genes 1 and 2 (BRCA1/2) is a critical predictive biomarker for poly (ADP-ribose) polymerase inhibitor (PARPi) therapy in epithelial ovarian cancer (EOC). The aim of this study is to define real-world rates and determinants of germline and somatic BRCA1/2 testing and subsequent PARPi utilisation in Australia using a national clinical quality registry. Methods: This multi-centre cohort study analysed data from 1503 women with non-mucinous EOC diagnosed between May 2017 and July 2022, captured by the Australian National Gynae-Oncology Registry (NGOR). We evaluated rates of germline and somatic testing and PARPi use, using multivariate logistic regression to identify associated clinical and demographic factors. Results: Overall germline and somatic testing rates were 68% and 32%, respectively. For the high-grade serous ovarian cancer (HGSOC) cohort, rates were higher, at 78% and 39%, respectively. Germline testing was significantly less likely for women aged >80 years (OR 0.49), those in regional areas (OR 0.61), and those receiving single-modality treatment. Somatic testing uptake increased significantly following public reimbursement for PARPi (p = 0.004). Among eligible women with a newly diagnosed BRCA pathogenic variant and advanced disease (n = 110), 52% commenced first-line maintenance PARPi. Conclusions: This national study offers valuable insights into Australian ovarian cancer care, highlighting opportunities to enhance testing equity for older women (aged >80) and regional patients. Furthermore, it identifies the translation of a positive test into PARPi therapy as a complex area that warrants further collaborative investigation to optimise patient outcomes.