Platinum vs non-platinum chemotherapy for platinum-resistant ovarian cancer: a systematic review and meta-analysis

Backgroundrecurrent ovarian cancer (OC) patients with platinum-free interval (PFI) <6 mo. are usually considered platinum-resistant and treated with non-platinum based chemotherapy. However, this was never confirmed in proper-conducted randomized trials. Methodswe queried the PubMed database for all full-text articles and abstracts on the treatment of patients with platinum-resistant ovarian cancer (PROC) in 01/01/2000-01/06/2019 timeframe. The PRISMA tool was used to ensure transparent reporting of the results. Inclusion criteria were: 1) morphologically confirmed epithelial ovarian cancer; 2) recurrent disease within 6 months after completion of platinum-based chemotherapy; 3) treatment with platinum- or non-platinum chemotherapy with agents that are routinely used for OC; 4) no concomitant therapy with targeted or investigational agents or non-platinum doublets; 5) defined response rate (RR) and assessment criteria. Proportion meta-analysis (random-effect model) and beta-regression were conducted to assess the impact of platinum agents on response rate as well as significance of other variables. In the beta-regression model response rate was a dependent variable, while platinum agents (yes or no), used non-platinum drugs and method of response assessment were independent variables. Statistical analysis was dose with meta, metafor and betareg packages of R software. Resultswe identified 7156 articles and screened them for title and abstract, 157 studies for further analysis. Overall, 6327 patients were included in the analysis, efficacy of non-platinum- and platinum-based therapy was assessed in 113 (n = 5272) and 44 (n = 1055) trials respectively. In meta-proportion random-effect model RR among patients treated with platinum-based and non-platinum chemotherapy RR was 36% (95% CI 30-41; I2 = 62%) and 16% (95% CI 14-19; I2=70%) respectively. For sensitivity analysis various regression models were made with different subsets of the trials and additional variables (including year of the trial, percentage of serous subtype of OC and median of prior therapy lines). Platinum was the strongest predictor of response in every developed model. Conclusionthis meta-analysis shows that patients with platinum-resistant ovarian carcinoma may derive significant benefit from reintroduction of platinum agents. These results support recent ESMO-ESGO consensus on treatment of recurrent ovarian cancer.