Optimization of Patient Selection for Surgical Approach to Peritoneal Metastases from Gastrointestinal Cancer Using Cytoreductive Surgery and Perioperative Chemotherapy

Gastrointestinal cancer can metastasize by hematogenous routes to the liver, by lymphatic channels to regional lymph nodes, and by penetration of the bowel wall to the peritoneal surfaces. For patients who have isolated peritoneal metastases, a new management plan with curative intent has evolved over the last 30 years. Now patients with peritoneal dissemination are evaluated by the multidisciplinary team for treatment by cytoreductive surgery plus perioperative chemotherapy. Major progress in the treatment of peritoneal metastases has occurred as a result of more clearly defined selection criteria. Now it is possible to identify patients who are likely to benefit and exclude those who may undergo extensive surgery with little or no added longevity or improved quality of life. Success with the combined treatment is dependent on complete cytoreductive surgery (CRS) before initiation of the perioperative chemotherapy. The large variations in success with peritoneal metastases treatment is dependent upon the success of hyperthermic perioperative chemotherapy (HIPEC) and early postoperative chemotherapy (EPIC) to maintain the absence of intraperitoneal cancer achieved by the surgical complete response. Prevention of a recurrence of peritoneal metastases after complete cytoreduction can be divided into two distinct time periods. Secondary prevention involves the peritoneal metastases diagnosed in follow up. The selection factors important in assessment of secondary prevention include the peritoneal cancer index (PCI), histological assessment of biological aggressiveness, lymph node status, distribution of peritoneal metastases, prior surgical score (PSS), and response to neoadjuvant chemotherapy. A new and promising investigation is prevention of peritoneal metastases as part of management of the primary malignancy. This use of CRS and HIPEC is referred to as primary prevention. The clinical features that suggest the need for CRS and perioperative chemotherapy are peritoneal nodules detected at the time of primary cancer resection, ovarian metastases, perforation through the primary cancer, adjacent structure or organ invasion, signet ring histology, fistula formation, or obstruction. The histopathologic features suggesting the need for CRS and perioperative chemotherapy available at the time of primary cancer resection include positive peritoneal cytology, positive imprint cytology, lymph nodes positive at or near the margin of resection, and T3/T4 mucinous cancer. The selection factors for secondary and primary prevention must be considered by the multidisciplinary team in the management of peritoneal metastases.