Purpose: The prognosis of peritoneal carcinomatosis (PC) from colorectal cancer has been improved with cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). However, benefits of postoperative chemotherapy (CT) are unclear.
Methods: This retrospective, multicenter study included 231 patients treated by CRS and HIPEC for isolated PC of colon cancer in four expert's centers. Overall survival (OS), progression-free survival (PFS), and peritoneal recurrence-free survival (PRFS) were compared between patients with adjuvant CT (started within 3 months after surgery) and patients with surveillance only.
Results: After exclusion of 10 patients for early postoperative death (4%), 221 patients were included (CT group: n = 151; surveillance group: n = 70). Main postoperative CT regimens (median of 6 cycles) were Folfox (28%), Folfiri bevacizumab (24.5%), Folfiri (16%), and Folfiri cetuximab (12.5%). The median OS after surgery was 43.3 months with no difference between CT and surveillance groups. In multivariate analysis, a low peritoneal cancer index (p < 0.0001) and a long delay between diagnosis of CP and HIPEC (p = 0.001) were associated with increased OS. The median PFS and PRFS were 12.4 and 17 months, respectively. At 1 year, more patients were without progression (p = 0.001) or PC recurrence (0.0004) in the CT group, but with prolonged follow-up this difference was no longer significant.
Conclusions: Early postoperative CT does not improve OS after CRS and HIPEC for colon carcinomatosis. However, a transient effect on PFS and PRFS was observed. A subgroup of patients who may benefit more from CT remain to be defined.