Survival in total preoperative verus perioperative chemotherapy for patients with metastatic high-grade appendiceal adenocarcinoma undergoing CRS/HIPEC.

Abstract

90 Background: Due to the relative infrequency of high grade appendiceal adenocarcinoma with peritoneal metastases, there is limited data to guide treatment strategies. Current practices for this disease are largely extrapolated from colon cancer patients with peritoneal metastases, who typically undergo six months of systemic chemotherapy in conjunction with cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). The optimal timing of chemotherapy in relation to CRS/HIPEC remains unknown. In this study, we compare the efficacy of peri-operative chemotherapy to pre-operative chemotherapy alone. Methods: This is a retrospective review of patients who underwent CRS/HIPEC for high grade appendiceal cancers from a tertiary referral center from 2014-2020. Outcomes were compared between patients who underwent planned 6 months of chemotherapy followed by CRS/HIPEC (pre-operative group) versus planned 3 months of chemotherapy both pre- and post-operatively (peri-operative group). Results: 85 patients were treated for metastatic high-grade appendiceal cancers during the study period, of whom24 were eligible for inclusion. Of those included, 16 were in the peri-operative group and 8 in the pre-operative group. Most patients were white (75%), non-Hispanic (96%) and female (54%). Patients in the pre-operative group tended to be older (65 vs. 56 years, p = 0.02). For patients with specified histologic grading, poorly differentiated tumors were common (50%). Signet ring cell histology (42%) and mucinous features (67%) were frequent as well. Median overall survival was similar between the pre-operative and peri-operative groups (32.3 vs. 31.6 months, p = 0.97), although patients undergoing peri-operative treatment received fewer total cycles of chemotherapy on average (14.1 vs. 9.5 cycles, p < 0.01). Half of the patients in the peri-operative group (8/16) did not complete their chemotherapy regimen, with 75% discontinuing therapy due to chemotherapy-related toxicities. Within the peri-operative group, a non-significant decrease in median survival was observed for those who did not complete chemotherapy (27.8 vs > 53.6 months, p = 0.22). Conclusions: Peri-operative and total pre-operative chemotherapy strategies are associated with similar survival in patients with high grade appendiceal cancers undergoing CRS/HIPEC. Peri-operative administration may be limited by chemotherapy-related toxicities.