Impact of number of cycles of platinum-based first-line chemotherapy for advanced urothelial carcinoma.

Abstract

426 Background: 6 cycles of platinum-based chemotherapy (CT) are conventionally targeted to treat locally advanced unresectable or metastatic urothelial carcinoma (UC). However, cisplatin is associated with significant cumulative toxicities, which render it challenging to deliver 6 cycles. Since this issue has not been investigated prospectively, we conducted a retrospective analysis. Methods: The Retrospective International Study of Invasive/Advanced Cancer of the Urothelium (RISC) database was used to conduct a retrospective analysis. The association of the number of cycles of platinum-based first-line CT with overall survival (OS) was investigated by a Cox regression utilizing multivariate analysis after controlling for previously recognized prognostic factors used in a nomogram ( Eur Urol, 2017). The primary analysis was a comparison of < 6 cycles vs. ≥6 cycles. Six-month landmark analysis was applied throughout, accounting for OS events. Additionally, we excluded patients (pts) receiving < 3 or > 9 cycles to reduce confounding due to early removal for toxicities, progression and patient decision and increased number of cycles due to response and pt-related factors. Results: Of 1020 pts available from RISC, 472 (cisplatin = 338, carboplatin = 134) were evaluable for the landmark analysis with 281 events. A total of 157 pts received 3-5 cycles (median 4) and 315 received 6-9 cycles (median 6). There was no significant difference between 3-5 vs. 6-9 cycles of platinum-based chemotherapy (HR 1.02, 95%CI: 0.77-1.33, p = 0.91). No significant interactions were observed with type of platinum (p = 0.09) and “completed planned CT” (p = 0.56). Comparison of 4 vs. 6 cycles (p = 0.57) and < 6 vs 6 vs 7-9 (p = 0.9) also yielded no significant differences for association with OS. No differential association was observed with survival for 3-5 vs. 6-9 cycles when examining by nomogram-defined risk group tertiles. Limitations of a hypothesis-generating retrospective analysis apply. Conclusions: 4 cycles of platinum based first-line CT appear adequate to treat advanced UC. The omission of excessive cycles will avoid unnecessary toxicities and facilitate better transition to second-line and switch maintenance therapy.