(PM P5) Implications of Postoperative Complications on Survival after CRS/HIPEC: A Multi-Institutional Analysis of the US HIPEC Collaborative

Background Postoperative complications(POCs) are associated with worse oncologic outcomes in various cancer histologies. The impact of POCs on the survival of patients with appendiceal or colorectal adenocarcinoma after cytoreductive surgery/heated intraperitoneal chemotherapy(CRS/HIPEC) is unknown. Methods US HIPEC Collaborative database(2000-2017) was reviewed for patients who underwent CCR0/1 CRS/HIPEC for appendiceal/colorectal cancer. Analysis was stratified by non-invasive appendiceal vs. invasive appendiceal/colorectal adenocarcinoma. POCs were grouped into infectious, cardiopulmonary, thromboembolic, intestinal dysmotility. Primary outcomes were overall survival(OS) and recurrence-free survival(RFS). Results Of 1304pts, median age was 55yrs(IQR47-64), 41% were male(n=537), 33% had non-invasive appendiceal(n=426), 67% had invasive appendiceal/colorectal cancer(n=878). In non-invasive appendiceal cohort, POCs were identified in 55%(n=233), and 3-year OS and RFS did not differ between patients who experienced a complication and those who did not(OS:94vs94%, p=0.26; RFS:68vs60%, p=0.15). In invasive appendiceal/colorectal adenocarcinoma cohort, however, POCs(63%;n=555) were associated with decreased 3-year OS(59vs74%, p<0.001) and RFS(32vs42%, p<0.001). Infectious POCs were the most common type(35%;n=196). On multivariable Cox regression, when accounting for gender, PCI, and incomplete resection(CCR1), infectious POCs in particular were associated with decreased OS compared to no complication(HR:2.08;95%CI:1.48-2.93;p<0.01) or other types of complications(HR:1.7;95%CI1.28-2.25;p<0.01). This association persisted for infectious POCs and reduced RFS(HR:1.61;95%CI1.23-2.10;p<0.01). Conclusion Postoperative complications are associated with decreased OS and RFS after CRS/HIPEC for invasive histologies, but not for an indolent disease like non-invasive appendiceal cancer. Of all complication types, infectious complications are the main driver for this association. The exact mechanism is not known, but may be immunologic. Efforts must target best practices and standardized prevention strategies to minimize infectious POCs.