Extent of Disease on Visceral Peritoneal Surfaces of Mucinous Appendiceal Neoplasms Controls Survival.

Objective: To determine causes of treatment failure of low-grade appendiceal mucinous neoplasms (LAMN). Background: For 3 decades, LAMN have been treated by cytoreductive surgery (CRS) and perioperative intraperitoneal chemotherapy. This combined treatment has resulted in a large change in the survival of these patients. Methods: A retrospective review of a prospectively maintained database was performed. A restricted cohort of patients with only LAMN histology and complete CRS were included in the statistical analysis. Results: Four hundred and fifty patients were available with a median follow-up of 15.3 years (range 10-35 years). The median age was 49.7 and there were 196 males (43.6%). The mean survival was 24.5 years. Extent of parietal peritonectomy, resection of uterus, ovaries and apex of vagina had no impact on survival. Variables that indicated an increased extent of disease on visceral peritoneal surfaces had a significant impact on survival. Early postoperative intraperitoneal chemotherapy with 5-fluorouracil did not augment hyperthermic intraperitoneal chemotherapy (HIPEC). Patients who required reoperation for recurrence or patients with class 4 adverse events had a reduced prognosis. Conclusions: The mean survival of LAMN treated by complete CRS and perioperative chemotherapy was 24.5 years. Extent of disease quantitated on visceral peritoneal surfaces by the extent of visceral resections was the variable associated with treatment failure. Peritonectomy plus HIPEC was able to control disease on parietal peritoneal surfaces. Not only a larger extent of disease but also its location on visceral peritoneal surfaces controlled survival.