Peritoneal surface malignancies (PSM) have been traditionally regarded as uniformly terminal conditions. The combination of cyto-reductive surgery and perioperative intraperitoneal chemotherapy has changed PSM management from palliation to possible cure. Due to the inherent differences in biological and clinical behavior, the optimal adaptation of comprehensive treatment to each PSM is still a matter of debate. A session of "The Fifth International Workshop on Peritoneal Surface Malignancy" (Milan, Italy, December 4-6, 2006) was committed to reach a consensus pertaining to conceptual and technical aspects of the loco-regional treatment of each PSM. The consensus developing process was based on principles of the Delphi method. A total of 103 international experts from 17 countries were included in six Working Groups (WG) for each of the following PSM: peritoneal mesothelioma, abdominal sarcomatosis, carcinomatosis of gastric, colo-rectal, appendiceal, and ovarian origin. Evidence reports were written by the respective WG. The main conflicting points (CP) regarding preoperative evaluation, patient eligibility, combined treatment methodology, postoperative follow-up and future investigational perspectives were summarized as a list of multiple-choice questions. Overall, 160 CP were identified. A consensus >= 51% of voters favoring one option was reached in 143/160 CP (89.4%). The general treatment guidelines and future investigational perspectives were defined.
