Rates of genetic testing in high grade serous ovarian cancer patients in the era of parp inhibitor therapy: a populationbased study

Objectives

All patients with high grade serous ovarian carcinoma (HGSC) should undergo germline genetic testing. Genetic consultations in Ontario, Canada only reached 13.3% in 2011. In 2016, PARP inhibitor maintenance therapy became available in Ontario for BRCA-positive HGSC patients. Given expanding treatment options, we re-examined genetic consultation rates among HGSC patients.

Methods

This retrospective cohort study identified patients diagnosed with HGSC between 2012–2019 using population-based administrative data. Genetics consultations were identified using Ontario Health Insurance Plan billing codes. Rates over time were determined. Multivariate analysis identified factors associated with genetics consults.

Results

This study included 4,645 HGSC patients from the provincial cancer registry. Mean age was 64.2 years (±SD 12.3) and 56.3% had stage 3–4 disease. Overall, approximately 35% attended genetics consultation. Genetics consult rate per year increased significantly from 21.6% to 42.6% (p<0.0001). Shorter times between diagnosis and genetics consult were observed after PARP inhibitors became available (68.1 vs. 34.1 weeks, p<0.0001). At institutions where medical geneticist billing was confirmed (n=2255), 55.7% attended a genetics consult, with a significant increase per year (32–68.9%, p<0.0001). Patients treated at designated cancer centres (OR 2.11, p<0.0001), diagnosed in later years (OR 1.33, p<0.0001), and from higher income groups (p<0.05) were more likely to attend genetics consultation, whereas older patients were less likely (OR 0.98, p<0.0001). After PARP inhibitors became available, genetics consultation rates plateaued (p=0.0001).

Conclusions

Between 2012–2019, genetic consultation rates improved significantly among HGSC patients; however there remains a significant proportion missing consults. Further exploration of modifiable factors that could improve consultation rates is warranted.