Recurrence and Survival Following Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Synchronous and Metachronous Peritoneal Metastases of Colorectal Origin

Simple Summary Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has notably improved the 5-year survival in colorectal cancer (CRC) patients with peritoneal metastases (PM). This study investigated recurrence patterns and survival outcomes in patients with synchronous versus metachronous PM following complete CRS+HIPEC. Among 310 patients studied from June 2006 to December 2020, the recurrence rate was 79.7%, and sites were most frequently isolated peritoneal and multifocal recurrence. Recurrence locations did not differ between synchronous and metachronous PM groups. Notably, patients with metachronous PM had a shorter disease-free survival compared to synchronous PM (9.4 vs. 12.5 months, p = 0.01); however, the overall survival was similar. Despite frequent recurrence, especially at extraperitoneal sites, long-term survival was achievable after CRS+HIPEC in CRC patients with PM.Abstract Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has improved the 5-year survival for colorectal cancer (CRC) patients with peritoneal metastases (PM). Little is known about recurrence patterns and recurrence rates between synchronous (S) and metachronous (M) PM following CRS+HIPEC. We aimed to describe the recurrence patterns, overall survival (OS) and disease-free survival (DFS) in S-PM and M-PM patients after complete CRS+HIPEC. From June 2006 to December 2020, a prospective cohort study included 310 CRC patients, where 181 patients had S-PM (58.4%) and 129 patients had M-PM (41.6%). After a median 10.3-month follow-up, 247/310 (79.7%) patients experienced recurrence, and recurrence sites included isolated peritoneal (32.4%), multifocal (peritoneal and liver and/or lung(s)) (22.7%), isolated liver (17.8%), isolated lung (10.5%) and other (16.6%) sites. Recurrence patterns did not differ between S-PM and M-PM. M-PM patients had an impaired DFS compared to S-PM patients (9.4 months (95% CI: 7.3-12.1) vs. 12.5 months (95% CI: 11.2-13.9), p = 0.01). The median OS was similar for S-PM and M-PM (38.4 months (95% CI: 31.2-46.8) vs. 40.8 months (95% CI: 28.8-46.8), p = 0.86). Despite frequent recurrence at extraperitoneal locations, long-term survival was achievable after CRS+HIPEC in CRC patients with PM. The recurrence patterns and OS did not differ between groups, yet M-PM patients had a shorter DFS.