Clinical determinants of treatment failure in patients with pseudomyxoma peritonei.

Pseudomyxoma peritonei is a mucinous cancer of low biologic aggressiveness that disseminates widely throughout the abdominopelvic cavity prior to diagnosis. Complete control of the disease process on peritoneal surfaces should translate into long-term disease-free survival. In a series of 120 patients with pseudomyxoma peritonei, 46 were defined as treatment failures after cytoreductive surgery and regional chemotherapy. Clinical features that correlated significantly with treatment failure were tumor site (colon vs. appendix), histopathology grade (grade II vs. grade I), preoperative cancer volume, and completeness of cancer removal by cytoreductive surgery. For grade I histopathology, treatment failure was 10 times more common after incomplete versus complete cytoreduction. For grade II histopathology treatment failure was three times more common with incomplete cytoreduction. Death from other causes was more common over the age of 65, and stroke was the most common diagnosis. The major causes of morbidity and mortality were related to progressive disease in the abdomen causing intestinal obstruction and biliary obstruction. When treatment failures were categorized as surgical (failure to cytoreduce) versus medical (failure of chemotherapy to sustain a response), there were 27 surgical and 10 medical treatment failures. Improvements in the cytoreductive approach await the development of surgical technologies to increase the total clearance of cancer from the abdominal cavity and chemotherapy treatments that are complete enough to sustain control of small-volume residual disease on all peritoneal surfaces.