Conditional Survival After Cytoreductive Surgery with Heated Intraperitoneal Chemotherapy for Low- and High-Grade Appendiceal Primaries

Survival of patients after cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy for appendiceal neoplasms is projected by conventional overall survival (OS) curves that do not address the survival time a patient has already accrued. We sought to study the conditional survival (CS) after CRS, contingent on patients surviving a fixed duration of time after surgery. A retrospective analysis of 493 appendiceal cancer patients from a prospective database was performed. OS was calculated for patients who achieved a complete CRS. CS was estimated based on Kaplan-Meier curves to determine what the patient's long-term survival (3-, 5-, 7-, or 10-year) would be if they were alive at 1, 2, or 3 years from surgery. OS at 5 and 10 years for 137 low-grade patients with complete resections was 83.3 and 74.2 %, respectively. For low-grade patients still alive at 3 years, 5- and 10-year CS was 93.4 and 83.2 %, respectively. For the 35 high-grade patients with complete CRS who survived to 3 years, CS at 10 years was 41.7 %, while their 10-year conventional OS was 24.6 %. Conventional analysis underestimates OS due to unpredictable variations in tumor biology. When adjusted for time already elapsed since surgery, improvements in survival estimates are more pronounced with high-grade tumors. CS outcomes can be used in determining the optimal frequency of long-term follow-up of these patients.