Survey sheds light on international genetic testing patterns in prostate cancer

Findings from a recent survey highlight physician’s real-world practice patterns for genetic/genomic testing in patients with metastatic castration-resistant prostate cancer (mCRPC) across the United States, Europe, and Asia.1

Limited insurance coverage and patient refusal were the most common reasons for patients not receiving testing.

Overall, data demonstrated wide variation in the proportion of patients recommended for testing and showed that barriers to testing remain.

“[The] treatment landscape in advanced prostate cancer is evolving,” the authors explained. “There is limited understanding of the factors influencing decision-making for genetic/genomic testing and the barriers to recommending testing and treatment in international real-world clinical practice following the approval of poly-adenosine diphosphate-ribose polymerase [PARP] inhibitors for [mCRPC].”

In total, the survey included 1195 physician respondents, of whom 407 (34%) completed the survey. Among those, 100 were from the USA, 132 were from the EU5 (France, Germany, Italy, Spain, and the UK), 100 were from Japan, and 75 were from China. Respondents were comprised of urologists (43%), oncologists (40%), and pathologists (17%).

Overall, respondents reported that 50% of patients with mCRPC are recommended for HRR mutation testing. Of those, 60% are specifically recommended for BRCA1/2 mutation testing and 65% received HRR mutation testing.

Physicians reported recommending HRR mutation testing for a median of 50% of patients with mCRPC in academic centers and 46% of patients with mCRPC in community centers. Testing was most often recommended at diagnosis of mCRPC (52%), diagnosis of mHSPC (45%), or after first-line treatment for mCRPC (44%).

The investigators then assessed the proportion of patients recommended for testing before and after approval of PARP inhibitors in the relevant regions. In the US, olaparib (Lynparza) and rucaparib (Rubraca) were approved in May 2020. Olaparib received subsequent approvals in the EU in November 2020, Japan in December 2020, and China in June 2021. Overall, a median of 20% of patients were recommended for genetic testing before these approvals, compared with 50% after.

The largest absolute increase in testing following PARP inhibitor approval was seen in Germany, with 10% of patients being recommended before the approval vs 70% of patients after. The smallest increase was seen in France, with 15% recommended before approval and 30% recommended after approval. In academic settings, the proportion of patients recommended for testing increased from 26% to 55% following the approvals. In community centers, the increase was from 10% to 50%.

These data were also assessed the year before and after the updated clinical guidelines. In the US, the National Comprehensive Cancer Center guidelines were updates in 2019. The guidelines in the EU, Japan, and China were updated in 2021. A median of 25% of patients were recommended for HRR mutation testing before the guideline updates compared with 50% of patients following the updates.

The largest absolute increase in testing was observed in US, increasing from 15% to 68%, and Germany, increasing from 20% to 70%. The smallest absolute increase was in France, which reported that 20% of patients were recommended for HRR mutation testing before the guideline update vs 25% after the update. In academic centers, the proportion of patients recommended for testing increased from 30% to 57%. The increase in community centers was larger, jumping from 20% to 50% following the guideline updates.

Limited insurance coverage and patient refusal were the most common reasons for patients in all regions not receiving testing following a recommendation for it. Specifically, challenges for adopting tissue biopsy/tumor for HRR mutation testing included patient refusal (41%), longer turnaround time to achieve results (40%), and limited access to genetic counseling (40%).

The authors added, “The reported lack of availability of adequate tissue for testing may present an opportunity for increased ctDNA testing.”

The authors concluded by noting several limitations of the current study, including the possibility for selection bias in that the results are based on a non-random convenience sample of physicians, as well as recall bias, which may impact the accuracy of results. They suggest that further study may be warranted.

“New PARPi approvals in the first-line settings for patients with mCRPC have occurred since this survey was completed in 2022. Future studies may assess the impact of these approvals on HRRm testing and treatment patterns for patients with [advanced prostate cancer], and the influence of insufficient HRRm testing on treatment patterns,” they concluded.

Reference

1. Gratzke C, Aggarwal H, Kim J, Chaignaud H, Oskar S. A cross-sectional survey of physicians to understand biomarker testing and treatment patterns in patients with prostate cancer in the USA, EU5, Japan, and China. Eur Urol Open Sci. doi:10.1016/j.euros.2024.07.113