Johnston, Fabian McCartney

40 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 cancer after cytoreductive surgery/heated intraperitoneal chemotherapy (CRS/HIPEC) is unknown. Methods: US HIPEC Collaborative (2000-17) was reviewed for patients who underwent CCR0/1 CRS/HIPEC for appendiceal/colorectal cancer. Analysis was stratified by non-invasive appendiceal neoplasm vs invasive appendiceal/colorectal adenocarcinoma. POCs were grouped into infectious, cardiopulmonary, thromboembolic and intestinal dysmotility. Primary outcomes were 3-yr overall survival (OS) and recurrence-free survival (RFS). Results: Of 1304 pts, median age was 55 yrs, 41% were male (n = 537), 33% had non-invasive appendiceal (n = 426) and 67% had invasive appendiceal/colorectal adenocarcinoma (n = 878). In the non-invasive appendiceal cohort, POCs were identified in 55% (n = 233) and OS and RFS did not differ between patients who experienced a complication and those who did not (OS 94 vs 94% p = 0.26; RFS 68 vs 60% p = 0.15). In the invasive appendiceal/colorectal adenocarcinoma cohort, however, POCs (63%; n = 555) were associated with decreased OS (59 vs 74% p < 0.001) and RFS (32 vs 42% p < 0.001). Infectious POCs were most common (35%; n = 196). On MV analysis 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%CI 1.28-2.25 p < 0.01). This association persisted for infectious POCs and reduced RFS (HR 1.61 95%CI 1.23-2.10 p < 0.01). Conclusions: Postoperative complications are associated with decreased OS and RFS after CRS/HIPEC for invasive histology, but not for an indolent disease like non-invasive appendiceal neoplasm. 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.

37 Background: While parenchymal hepatic metastases were previously considered a contraindication to cytoreductive surgery(CRS) and heated intraperitoneal chemotherapy(HIPEC), liver resection(LR) is increasingly performed concomitantly with CRS/HIPEC. As this practice continues to expand, identification of preoperative factors associated with poor outcomes is paramount. Methods: Patients from the US HIPEC Collaborative(2000-2017) with invasive appendiceal or colorectal adenocarcinoma undergoing primary, curative intent CRS/HIPEC with CC0-1 resection were included. LR was defined as a formal parenchymal resection. Primary endpoints were postoperative complications and overall survival(OS). Results: 658 patients were included. Average age was 54 years and 45% were male; 83 (15%) underwent liver resection of colorectal (58%) or invasive appendiceal (42%) metastases. Liver resection patients had more complications (81 vs 60%; p = 0.001), greater number of complications (2.3 vs 1.5; p < 0.001), and required more reoperations (22 vs 11%; p = 0.007) and readmissions (39 vs 25%; p = 0.014) than non-liver resection patients. Liver resection patients had decreased OS (2-year OS 62% vs 79%, p < 0.001), which persisted on multivariable Cox regression when accounting for PCI and histology type. Preoperative factors associated with decreased OS on multivariable analysis in patients undergoing liver resection included age < 60 years (HR:3.61), colorectal histology (HR:3.84), and multiple liver tumors (HR:3.45) (all p < 0.05). When assigning one point for each factor, there was an incremental decrease in 2-yr survival as the risk score increased from 0 to 3 (0: 100%; 1: 91%; 2: 58%; 3: 0%; p < 0.001). Conclusions: As concurrent liver resection with CRS/HIPEC has become more common, we created a simple risk score to stratify patients considered for CRS/HIPEC with liver resection. These data aid in striking the balance between an increased perioperative complication profile with the potential for improvement in overall survival.

184 Background: Patient age is often a significant factor in preoperative selection for major abdominal surgery. Its association with postoperative outcomes in patients undergoing cytoreductive surgery(CRS) and hyperthermic intraperitoneal chemotherapy(HIPEC) remains ill-defined. Methods: The US HIPEC Collaborative database(2000-2017) was reviewed for patients who underwent a CCR0/1 CRS/HIPEC. Age was categorized into < 65 or >65yrs. Primary outcomes were postoperative major complications, readmission, 30-day mortality, and non-home discharge(NHD). Analysis was stratified by disease histology: non-invasive(appendiceal LAMN/HAMN), and invasive(appendiceal/colorectal adenocarcinoma). Results: Of 1090pts identified, 22% were >65yrs(n = 240), 59% were female(n = 646), 25% had non-invasive(n = 276) and 51% had invasive(n = 555) histology. Median PCI was 13(IQR7-20). Patients >65yrs had a higher rate of major complications(37vs26%, p = 0.02), readmission(28vs22%,p = 0.05), 30-day mortality(3vs1%,p = 0.02), and NHD(12vs5%,p < 0.01) compared to those < 65yrs. On multivariable analysis accounting for extent of disease as measured by PCI, for non-invasive histology, age >65yrs was an independent predictor for NHD(OR:2.54,95%CI:1.08-5.99,p = 0.03), but not major complications. For invasive histology, even when accounting for PCI, age >65yrs was an independent predictor for both NHD(OR:2.54,95%CI:1.08-5.98,p = 0.03) and major complications(OR:2.04,95%CI:1.16-3.59,p = 0.05). Age was not associated with hospital readmission or 30-day mortality for any histology. Conclusions: Regardless of histology, patients >65yrs are nearly at three-fold increased risk for non-home discharge after CRS/HIPEC. For invasive histology, age >65yrs is also associated with increased major complication rates, but the procedure seems to be better tolerated when performed for indolent biology. These data inform preoperative counseling and risk stratification. Early planning for discharge disposition in this high-risk population can potentially translate to cost savings.