Outcomes in Peritoneal Dissemination from Signet Ring Cell Carcinoma of the Appendix Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.

BACKGROUND: Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is standard treatment for peritoneal dissemination from appendiceal cancer (AC); however, its role in high-grade histopathologic subtypes (high-grade mucinous carcinoma peritonei [HGMCP] and HGMCP with signet ring cells [HGMCP-S]) is controversial due to their aggressive behavior. This study analyzed clinical outcomes of high-grade AC after CRS/HIPEC.

METHODS: A prospective database of CRS/HIPEC procedures for HGMCP performed from 1998-2017 was reviewed. Perioperative variables and survival were analyzed.

RESULTS: Eighty-six HGMCP and 65 HGMCP-S were identified. HGMCP had more positive tumor markers (TM) (CEA/CA-125/CA-19-9) than HGMCP-S (63% vs 40%, p = 0.005). HGMCP had higher Peritoneal Cancer Index (32 vs 26, p = 0.097) and was less likely to have positive lymph nodes (LN) than HGMCP-S (28% vs 69%, p = < 0.001). Complete cytoreduction was achieved in 84% and 83%, respectively. PFS at 3- and 5-years was 59% and 48% for HGMCP vs 31% and 14% for HGMCP-S. Median PFS was 4.3 and 1.6 years, respectively (p < 0.001). OS at 3- and 5-years was 84% and 64% in HGMCP vs 38% and 25% in HGMCP-S. Median OS was 7.5 and 2.2 years, respectively (p < 0.001). LN negative HGMCP-S had longer median PFS and OS than LN positive HGMCP-S (PFS: 3.4 vs 1.5 years, p = 0.03; OS: 5.6 vs 2.1 months, p = 0.021).

CONCLUSIONS: The aggressive histology of HGMCP-S is associated with poor OS, has fewer abnormal TM, and is more likely to have positive LN. However, CRS/HIPEC can achieve a 5-year survival of 25%, which may improve to 51% with negative LN.