Iterative Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy for Recurrent Mucinous Adenocarcinoma of the Appendix.

Background: Recurrence after cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) for appendiceal tumors (AT) with mucinous carcinomatosis peritonei (MCP) is common. The evidence favoring iterative procedures (iCRS/HIPEC) is limited, and its benefit is not clear for all patients.

Methods: Retrospective (1998-2020) cohorts of AT patients with MCP recurrence after the first CRS/HIPEC were analyzed. Outcomes were compared within tumor grades between iCRS/HIPEC patients and matched control patients without iCRS/HIPEC using propensity score matching (1:1). Post-recurrence survival (PRS) was measured from the date of recurrence after the first CRS/HIPEC to death or last contact.

Results: Overall, 55 iCRS/HIPEC patients were identified: 36 low-grade (LGMCP) patients, 13 high-grade (HGMCP) patients, and 6 HGMCP patients with signet-ring features (HGMCP-S). Nine patients had a third CRS/HIPEC. The median peritoneal cancer index (PCI) scores were 33, 19 and 10, with CC-0/1 achieved for 94.4%, 78.2% and 88.9% of the patients after the first, second, and third CRS/HIPEC, respectively. No 90-day postoperative mortality occurred. The median progression-free survival from the first CRS/HIPEC was 19.7 months for the iCRS/HIPEC patients versus 14.2 months for the matched control patients (p = 0.43). The median PRS was 80.2 months for iCRS/HIPEC versus 36.2 for the control patients (p < 0.001). For the iCRS/HIPEC versus the matched control patients, the median PRS by tumor grade was 174.1 versus 51.9 (p < 0.001) for the LGMCP, 42.0 versus 12.4 (p = 0.02) for the HGMCP, and 15.4 versus 8.1 months (p = 0.61) for the HGMCP-S patients, respectively.

Conclusions: Selected low- and high-grade appendiceal cancer patients with MCP recurrence able to undergo iterative CRS/HIPEC procedures showed favorable outcomes and such patients should be considered for surgery when feasible. This survival benefit with iCRS/HIPEC is not evidenced in recurrent MCP with signet ring cell morphology.