(PM P28) Completeness of Cytoreduction, Regardless of Tumor Burden, is Associated with Improved Survival after CRS/HIPEC for LAMN

Background: Cytoreductive surgery with hyperthermic intraperitoneal chemoperfusion (CRS/HIPEC) is considered standard treatment for peritoneal metastases from low-grade appendiceal mucinous neoplasms (LAMN). This study evaluates predictors of survival after CRS/HIPEC for LAMN.

Methods: A retrospective review of adult patients who underwent CRS/HIPEC for LAMN was performed at 12 U.S. institutions from 2000 – 2012. Univariate analysis of demographic/pathologic factors was performed and survival determined by Kaplan-Meier analysis. Cox proportional hazard regression was performed.

Results: 178 patients underwent CRS/HIPEC for LAMN. Median age was 55 years (IQR: 46-63); 63% were female. Median peritoneal cancer index (PCI) score was 15.5 (IQR: 9-21). A completeness of cytoreduction score (CC) of 0/1 was achieved in 79%. Median follow-up was 4.9 (IQR 2-7) years. 95 patients (54%) had no evidence of disease. 34 (19%) patients were deceased: disease specific mortality was 65%. Median overall survival (OS) was 9.3 years. Univariate analysis showed a significant association between CC and survival (HR 1.90, 95% CI 1.40-2.59; p<0.001; Table 1). On multivariable analysis controlling for both clinically relevant and statistically significant covariates, incomplete cytoreduction (CC 2/3) yielded an adjusted hazard ratio (aHR) of 2.15 (95% CI 1.40-3.29; p<0.001). PCI score did not have an effect on long-term survival.

Conclusion: CRS/HIPEC is effective for the management of LAMN with peritoneal metastases. Completeness of cytoreduction is the greatest predictor of survival and offers patients the potential for long-term cure. PCI score should not be used as a means to exclude patients who can achieve a complete cytoreduction from surgery.