Adjuvant HIPEC in patients with colon cancer at high risk of peritoneal metastases: Primary outcome of the COLOPEC multicenter randomized trial.

482Background: Patients with T4 or perforated colon cancer are at high risk (~25%) of peritoneal metastases (PM). Sensitivity of imaging modalities for PM is limited and the majority of patients is diagnosed in a palliative setting. This provides a rationale for adjuvant hyperthermic intraperitoneal chemotherapy (HIPEC). In this study, the effectiveness of adjuvant HIPEC in reducing the risk of PM was determined. Methods: In this multicenter trial, patients with T4 (either cT4 or pT4, N0-2, M0) or perforated colon cancer, who underwent curative resection were randomized to adjuvant HIPEC followed by routine adjuvant systemic chemotherapy or to adjuvant systemic chemotherapy alone (1:1). Adjuvant HIPEC with oxaliplatin was performed simultaneously (9%) or within five-eight weeks (91%) after the primary tumor resection. Patients without evidence of recurrent disease at 18 months based on CT imaging underwent diagnostic laparoscopy in both arms. The primary endpoint was PM free survival (PMFS) at 18 months u...