Patterns of first-line systemic therapy delivery and adoption of bevacizumab in advanced ovarian cancer in Ontario, Canada.

Abstract

292 Background: Initial treatment of epithelial ovarian cancer (EOC) consists of combination of cytoreductive surgery (CSR) and/or chemotherapy. Targeted therapies such as bevacizumab have shown to improve outcomes in a subset population with high-risk features. Real-world patterns of systemic therapy delivery in EOC in the modern era are not well understood. Our objective is to evaluate the patterns of first-line systemic treatment of advanced EOC in Ontario, focusing on adoption of bevacizumab, which was approved for use in 2016. Methods: We conducted a retrospective, population cohort study using administrative databases held at the ICES in Ontario, Canada. Patients diagnosed with non-mucinous EOC between 2014 and 2018 were identified from the Ontario Cancer Registry; early-stage disease was excluded. Information on systemic therapy was obtained from Activity Level Reporting and New Drug Funding Program databases. Provider of care (gynecologic oncologist vs medical oncologist) information was obtained from billing codes. Academic cancer centers were identified using validated systemic facility codes from Cancer Care Ontario. Statistical analyses include descriptive statistics, t-tests, and multivariable logistic regression using SAS. Results: Out of 4,680 cases diagnosed with EOC during the study period, 3,632 (77.6%) were considered advanced stage. Median age of cohort was between 65-70, and the majority had Charlson score of 1-2 (97%) and are urban (91.8%). A total of 3,181 (87.6%) patients underwent CRS and 2,722(74.9%) patients underwent chemotherapy. Of those who received chemotherapy, 1,259 (46.2%) received neoadjuvant chemotherapy, 1,012 (37.2%) received upfront CRS, and 451(16.5%) received chemotherapy only. The majority of chemotherapy was delivered by gynecologic oncologists (60.6%) and in academic cancer centres (61.7%). There was no significant difference in use of neoadjuvant chemotherapy between medical oncologists and gynecologic oncologists (p = 0.67). Only 53 chemotherapy patients (1.9%) received bevacizumab containing-regimen in the first-line setting. Medical oncologists were 4 times more likely to administer bevacizumab-containing regimen compared to gynecologic oncologists (OR 4.03, 95% CI.29 – 7.36) after adjusting for age, stage, Charlson score and rurality score on logistic regression. Delivery of bevacizumab is relatively higher in non-academic cancer centres (OR 2.61, 95% CI 2.32- 2.94) while 83% of intraperitoneal chemotherapy is delivered in academic cancer centres. Conclusions: Patterns of care of EOC in Ontario remain heterogenous between care providers and institutions, while uptake of bevacizumab for first-line treatment of EOC remains low. Factors leading to low uptake and real-world outcomes should be explored.