(PM P10) The Intersection of Age and Tumor Biology with Postoperative Outcomes in Patients After Cytoreductive Surgery and HIPEC

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 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. Mean LOS was higher for NHD patients compared to their counterparts (29vs11days,p<0.01). 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 better tolerated when performed for indolent biology. These data inform preoperative counseling/risk stratification. Early planning for discharge disposition in this high-risk population can potentially translate to cost savings.