PCI is Not Predictive of Survival After Complete CRS/HIPEC in Peritoneal Dissemination from High-Grade Appendiceal Primaries

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is a treatment option in patients with carcinomatosis from high-grade appendiceal (HGA) primaries. It is unknown if there is a Peritoneal Carcinomatosis Index (PCI) upper limit above which a complete CRS/HIPEC does not assure long-term survival.Retrospective analysis from three centers was performed. The PCI was used to grade volume of of disease. Survival in relation to PCI was studied on patients with complete cytoreduction.Overall, 521 HGA patients underwent CRS/HIPEC from 1993 to 2015, with complete CRS being achieved in 50% (260/622). Mean PCI was 14.8 (standard deviation 8.7, range 0-36). Median survival for the complete CRS cohort was 6.1 years, while 5- and 10-year survival was 51.7% (standard error [SE] 4.6) and 36.1% (SE 6.3), respectively. Arbitrary cut-off PCI limits with 5-point splits (p = 0.63) were not predictive of a detrimental effect on survival as long as a complete CRS was achieved. A linear effect of the PCI on survival (p = 0.62) was not observed, and single-point PCI cohort splits within a PCI range of 5 to 10 were not predictive of survival for complete CRS patients. The PCI correlated with the ability to achieve a complete CRS, with a mean PCI of 14.7 (8.7) for completeness of cytoreduction (CC)0, 22.3 (7.8) for CC1 and 26.1 (9.5) for CC2/3 resections (p = 0.0001, hazard ratio 1.12, 95% confidence interval 1.09), with an HR of 1.15 for each 1-unit increase in the PCI score. Only 21% of the cohort achieved a complete CRS with a PCI ≥ 21.The PCI correlates with the ability to achieve a complete CRS in carcinomatosis from HGA. PCI is not associated with survival as long as a complete CRS can be achieved.