The Effect of Prior Nondefinitive Surgery on Perioperative Outcomes and Survival in Mucinous Appendix Cancer Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

<b>Introduction:</b> Peritoneal metastases (PM) from mucinous appendix cancer (MAC) are common and often mismanaged. While cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is standard, many patients undergo nondefinitive surgery. We compared outcomes in MAC patients undergoing CRS/HIPEC after limited vs excessive prior surgeries. <b>Methods:</b> We conducted a retrospective analysis of MAC patients (1998-2023) from a single-center prospective database who underwent CRS/HIPEC. Surgical history was evaluated using the prior surgical score (PSS). Perioperative characteristics were compared between PSS-0/1 and PSS-2/3 groups. Logistic regression identified factors associated with extensive prior surgery. Overall survival (OS) was analyzed with Kaplan-Meier and Cox regression. <b>Results:</b> Of 351 eligible cases, 221 (63%) had PSS-0/1 and 130 (37%) had PSS-2/3. Most individuals with PSS-2/3 were women (89.2%, n = 116). Only female sex was significantly associated with the higher likelihood of PSS-2/3 (odds ratio: 9.02, <i>P</i> < .001). PSS-2/3 patients had longer time from diagnosis to CRS/HIPEC (<i>P</i> < .001), longer CRS/HIPEC procedure (<i>P</i> = .007), and greater blood loss (<i>P</i> = .038). Complete cytoreduction (CC) rates were similar (<i>P</i> = .227). Despite comparable major complication rates, PSS-2/3 patients had more transfusions (<i>P</i> = .016), infections (<i>P</i> = .048), and pulmonary complications (<i>P</i> = .028). Five-year OS was 76% and 66% for PSS-0/1 and PSS-2/3 groups, respectively (<i>P</i> = .049). After adjusting for age, tumor burden, CC-score, and histology, PSS-2/3 was not significantly associated with shorter OS (hazard ratio: 1.32; <i>P</i> = .139). <b>Conclusion:</b> Females with MAC are more likely to have extensive surgeries, delaying CRS/HIPEC and compromising safety. This highlights the importance of general surgeons and gynecologists limiting the surgical extent and referring patients to an HIPEC center.