P-117 Survival outcomes following systemic chemotherapy in stage IVA/B high-grade mucinous appendiceal cancer after unsuccessful cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

Abstract

The appropriate management of patients with unresectable mucinous appendiceal cancer (MAC) with peritoneal spread (Stage IVA/B) after a failed attempt at cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is unclear. Systemic chemotherapy (SCT) may be an option; however, data regarding its effectiveness in stage IVA/B MAC is controversial. This study aimed to assess outcomes after SCT in patients with unresectable peritoneal metastases from high-grade MAC. A single-center retrospective cohort study was conducted using a prospective CRS/HIPEC database. Stage IVA/B high-grade MAC patients deemed surgical candidates, but had an aborted CRS/HIPEC or underwent only palliative HIPEC were included. Overall survival (OS) was compared between patients with postoperative SCT and those without. Among 80 identified patients, 20 received SCT and 60 did not (NoCT). There was no difference between groups in age (p=0.314), sex (p=0.796), proportion of newly diagnosed patients (p=0.893), histopathologic subtype (p=0.108), preoperative chemotherapy (p=0.962), preoperative tumor markers (CA 19-9, CA 125, CEA), and postoperative major complication rates (p=0.358). Both groups had extensive residual disease (median peritoneal cancer index: 39 vs 39, p=0.956). SCT regimens included: 5-FU/capecitabine in 25% (n=5), FOLFOX in 30% (n=6), FOLFIRI in 30% (n=6), FOLFIRINOX in 5% (n=1) with/without bevacizumab. Regimens were unknown in 10% (n=2). Median number of cycles was 12 (IQR: 6-15) and median time between the procedure and SCT was 7 (IQR: 5-10) weeks. Median follow-up was 65 months. Median OS was significantly higher in the SCT group (26 months; 95%CI: 10.8-41.5) versus NoCT group (10 months; 95%CI: 7.3-12.7) (p < 0.0001), with hazard ratio 0.30 (95%CI: 0.16-0.57, p < 0.0001). Systemic chemotherapy improves overall survival in high-grade MAC patients with unresectable peritoneal metastases who were deemed surgical candidates, but underwent an unsuccessful CRS/HIPEC attempt. Further prospective studies with a larger sample size are required to identify patient subgroups who benefit the most from SCT.