Delaying Surgery After Neoadjuvant Chemotherapy Affects Survival in Patients with Colorectal Peritoneal Metastases: A BIG-RENAPE Network Multicentric Study

BACKGROUND: Multimodal treatment for patients with peritoneal metastases (PM) from colorectal cancer (CRC), including perioperative chemotherapy (CT) plus complete resection, is associated with prolonged survival. The oncologic impact of therapeutic delays is unknown. OBJECTIVE: The aim of this study was to assess the survival impact of delaying surgery and CT. METHODS: Medical records from the national BIG RENAPE network database of patients with complete cytoreductive (CC0–1) surgery of synchronous PM from CRC who received at least one neoadjuvant CT cycle plus one adjuvant CT cycle were retrospectively reviewed. The optimal interval between the end of neoadjuvant CT to surgery, surgery to adjuvant CT, and total interval without systemic CT were estimated using Contal and O’Quigley’s method plus restricted cubic spline methods. RESULTS: From 2007 to 2019, 227 patients were identified. After a median follow-up of 45.7 months, the median overall survival (OS) and progression-free survival (PFS) was 47.6 and 10.9 months, respectively. The best cut-off period was 42 days in the preoperative interval, no cut-off period was optimal in the postoperative interval, and the best cut-off period in the total interval without CT was 102 days. In multivariate analysis, age, biologic agent use, high peritoneal cancer index, primary T4 or N2 staging, and delay to surgery of more than 42 days (median OS 63 vs. 32.9 months; p = 0.032) were significantly associated with worse OS. Preoperative delay of surgery was also significantly associated with PFS, but only in univariate analysis. CONCLUSION: In selected patients undergoing complete resection plus perioperative CT, a period of more than 6 weeks from completion of neoadjuvant CT to cytoreductive surgery was independently associated with worse OS.