Multicentric randomised trial. The goal of this clinical research study is to learn if hyperthermic intraperitoneal chemotherapy (HIPEC) will help to decrease the rate of peritoneal carcinomatosis(PC) in patients with high risk of developing PC of colorectal cancer. The safety of this treatment will also be studied.

Hyperthermic intraperitoneal chemotherapy(HIPEC) is a recently validated option for the treatment of peritoneal carcinomatosis from colorectal or ovarian origin. This therapeutic program demonstrated a significant improvement of overall survival of the disease. It is not yet known whether surgery followed by HIPEC is effective on decreasing the rate of peritoneal carcinomatosis(PC) in patients with high risk of developing PC of colorectal cancer.Patients with a high risk of developing colorectal Peritoneal Carcinomatosis (PC), defined by Colorectal Cancer With a Resected Minimal Synchronous PC or Ovarian Metastases, or identified T4 by intraoperative pathological diagnosis, or Tumour Rupture in the Abdominal Cavity. If patients with a high risk of developing PC identified by preoperative examination, they will be informed and will sign the consent. After complete resection of their tumor, they will be randomised to surveillance alone (control group) or HIPEC (experimental group). All patients will receive the current standard postoperative adjuvant treatment : 6 months of systemic chemotherapy (currently including FOLFOX4, mFOLFOX6, CapeOx or Capecitabine regimen which could be modified if the standard is modified). Then a work-up is done to find recurrence. If the recurrence occurs, the patient will be treated with the best known treatment.

Inclusion Criteria:

• Patients presenting with the following history:

  1. Histologically-proven colorectal adenocarcinoma

  2. Presenting at the time of resection of the primary with one of the following 5 criteria (criteria indicating a high risk of developing PC) :

     • Minimal PC, resected at the same time as the primary
     • Rupture of the primary tumour inside the peritoneal cavity,
     • Intraoperative rupture of the primary tumour during surgery
     • Histologically-proven T4 colorectal adenocarcinoma

• Who have received standard systemic adjuvant chemotherapy (6 months of systemic chemotherapy) :

  1. Chemotherapy with FOLFOX4, mFOLFOX6, CapeOx or Capecitabine(the current standard treatment; it can be modified in the future in the two groups, if the standard is modified)
  2. Given on an intent-to-treat basis (it can be stopped prematurely for miscellaneous reasons)

• Patients who do not present any sign of tumour recurrence at the end of these 6 months of chemotherapy

• Patients with the following general characteristics:

  1. Age between 18 and 75 years
  2. Performance Status (ECOG) 0, 1 or 2, life expectancy > 12 weeks
  3. Adequate renal, and bone marrow function: a. Leukocytes >/= 3,000/microL; b. Absolute neutrophil count >/= 1,500/microL; c. Platelets >/= 100,000/Ul; d. Serum creatinine \