Increased Incidence of Liver Metastases in Colorectal Versus Appendiceal Adenocarcinoma Peritonectomy Patients Despite Equivocal Survival.

Abstract

Colorectal adenocarcinoma (CRAdenoCa) and appendiceal adenocarcinoma (AAdenoCa) are diseases of the same histopathological type that metastasise to the liver and peritoneum. In selected subgroups, peritonectomy and heated intraperitoneal chemotherapy (HIPEC) may be indicated as part of the multimodal treatment plan. However, literature comparing the survival outcomes and preoperative tumour activity and burden of CRAdenoCa and AAdenoCa peritonectomy patients without synchronous liver metastases (sLM) is scarce. Little is also known about the comparative incidence of sLM and metachronous LM (mLM) between CRAdenoCa and AAdenoCa peritonectomy patients. This study aimed to clarify the above. A retrospective cohort study of 684 CRAdenoCa and AAdenoCa primary peritonectomy patients between 2001-2021 was conducted at St George Hospital in Sydney, Australia. Median overall survival (years) was equivocal between CRAdenoCa and AAdenoCa peritonectomy patients (1.7 vs. 1.9, p=0.35). Peritoneal cancer index and preoperative carcinoembryonic antigen (CEA) were significantly elevated (25 vs. 9, p<0.0001 and 7.9 vs. 5, p=0.0080) in AAdenoCa versus CRAdenoCa peritonectomy patients without sLM. The incidence of sLM and mLM was increased in CRAdenoCa peritonectomy patients (24% vs. 3.1%, p<0.0001 and 26% vs. 10%, p=0.0001). This study demonstrates similar survival outcomes between CRAdenoCa and AAdenoCa peritonectomy patients. Despite elevated preoperative tumour burden and biological activity in AAdenoCa patients, CRAdenoCa patients had higher rates of sLM and mLM. Further studies are warranted to validate and identify cellular and molecular targets that increase CRAdenoCa's ability to metastasise to the liver.