Patient selection and treatment of peritoneal carcinomatosis from colorectal and appendiceal cancer.

Colorectal cancer is a disease process that disseminates through lymphatic channels, through hematogenous routes, and by invasion through the bowel wall. These mechanisms result in lymph node metastases, liver metastases, and peritoneal seeding. Although lymphatic and venous dissemination requires an invasive local process, peritoneal seeding may occur with both high grade and low grade malignancies. Cancer dissemination that causes liver and lymphatic metastases occurs prior to surgical resection of the primary colorectal cancer. Peritoneal seeding and seeding of the resection site (local recurrence) may also occur as a result of the surgical trauma that accompanies resection of the primary lesion. Leakage of malignant cells from transected lymphatic channels may be the mechanism of this intraoperative intraperitoneal cancer dissemination. To limit the progression of peritoneal seeding and to treat large volume, low grade intraabdominal tumor deposits, combinations of cytoreductive surgery and intraperitoneal chemotherapy have been successfully employed. Selection factors that correlate with long-term benefit are (1) low grade of malignancy, (2) lack of lymph node or liver metastases, and (3) treatment of low volume disease. For patients with moderate or high grade colorectal cancer, only a low volume of disease can be treated successfully. For patients with low grade cancer, peritonectomy procedures are used to achieve minimal residual disease before initiating the intraperitoneal chemotherapy. In properly selected patients, peritoneal carcinomatosis from colorectal and appendiceal cancer is a treatable condition that may result in long-term disease-free survival.