Commentary (Douglass): Managing the Peritoneal Surface Component of Gastrointestinal Cancer

No American surgeon has the same breadth of experience with extensive peritoneal resection as Dr. Paul Sugarbaker. Moreover, only a few clinicians worldwide have the same level of experience with intraperitoneal chemotherapy for a variety of intraperitoneal cancers, particularly after peritoneal resection.[ 1] The value of these therapies is unquestionable in patients with lowgrade tumors confined to the peritoneal cavity. A number of patients treated in this fashion show no evidence of recurrent disease a decade or more posttreatment. On the other hand, many of these tumors progress slowly, with a proportion of untreated patients surviving 3, 5, or more years. Although 60% of resected patients survive 5 years, their tumors may still recur and lead to death 10 or more years later. The terminal phase of this disease tends to be prolonged and for the patient, miserable. Invasive Progression
Pseudomyxomas adhere to peritoneal surfaces in their early stages but become invasive as they progress. Notching of the liver surface seen on computed tomography predicts progression to cancer with invasive capability. Minute peritoneal metastases are not uncommonly found in patients with gastric, gallbladder, pancreatic, and colonic cancers. When such metastases are confined to the immediate area of the primary cancer, localized peritoneal resection combined with radical resection of the primary cancer followed by intraperitoneal chemotherapy may become a rational approach for patients with gallbladder and colon cancers.[1] However, minute tumor seedlings in the pelvis, at the base of the small bowel, along the mesenteric border of the bowel, or under the diaphragm suggest more widespread dissemination for which the risk-benefit ratio of aggressive therapy must be considered. Treatment Strategies
Extensive peritoneal resection is a tedious and meticulous procedure, sped up somewhat by selective use of electroevaporation or argon laser destruction. Resection of the entire peritoneal surface often takes 18 hours to perform, whereas localized resection can be performed more expeditiously with low mortality and morbidity rates. Postoperatively, shifts in fluid from the raw peritoneal surfaces resemble those associated with extensive burns and require continuous monitoring for fluid replacement. We prefer that the initial lavage of the peritoneal cavity be performed with hypotonic solutions to lyse freefloating tumor and red blood cells and facilitate removal of clots and debris by prompt suction evacuation before closing the abdomen. Peritoneal lavageage and intraperitoneal thermochemotherapy can then proceed using 2 L of intraperitonenal fluid to ensure that all recesses of the peritoneal cavity are exposed to the solution. Postchemotherapy flushes of the peritoneum should continue until the drainage is clear. Complications and Exceptions
While chemical peritonitis is not an uncommon complication of intraperitoneal chemotherapy,[2] pancreatitis can also occur.[3] Pancreatitis develops more commonly when the peritoneal surface over the pancreas has been removed as part of the peritoneal resection of the lesser peritoneal sac; it is not seen after radical D2 gastrectomy, during which this lining is routinely removed, suggesting that the intraperitoneal chemotherapy is the precipitating factor. Dr. Sugarbaker recommends that reconstruction of the gastrointestinal tract be deferred until after the intraoperative intraperitoneal chemotherapy has been completed, although others have suggested that this is unnecessary.[ 1,4] If anastomosis is delayed until after intraperitoneal chemotherapy has been completed, we would suggest that the ends of the bowel be trimmed a few millimeters to remove anastomotic mucosa that has been exposed to the drugs, because many antineoplastic agents delay wound healing. Re-exploration of patients who have received intraperitoneal chemotherapy often reveals a glistening, well-defined capsule[5] containing a sac that is smaller than the original peritoneal cavity. If the tumor recurs, it is usually found in areas that were once the walls of the peritoneal cavity but are now behind the wall of this fibrous sac. Dr. Sugarbaker indicates that there are 13 peritoneal cavity areas but only lists 12. The 13th is the lesser peritoneal sac. He also describes the technique for control of peritoneal metastases of colon cancer, but the tables refer to gastric cancer. Intraperitoneal chemotherapy for gastric cancer must be accompanied by a wide D2 resection because peritoneal and lymphatic metastases are frequently associated with this primary.[6] Unfortunately, we still do not have optimal agents for management of gastric cancer. Thus, except in cases of serosa- invading but peritoneum-negative gastric cancer, intraperitoneal treatment remains experimental.[7-9] Conclusions
Peritoneal resection, with or without intraperitoneal chemotherapy, is an accepted treatment for pseudomyxoma peritonei. Dr. Sugarbaker makes a strong argument for its use in selected colon cancer patients, provided that an R-O surgical resection can be performed. For other gastrointestinal cancers, the potential benefits of surgery and intraperitoneal chemotherapy remain unproven and should only be used when following a peer-reviewed protocol under the guidance and auspices of an institutional review board. Dr. Sugarbaker is to be commended for his continuing research into the management of the peritoneal dissemination of cancer.