ABSTRACT
BACKGROUND: The presence at diagnosis, or development of, colorectal peritoneal metastases (CPM) is common in colorectal cancer. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) show promising results in selected patients with CPM. The current study aimed to describe oncologic outcomes of patients with CPM, focusing on recurrence patterns and risk factors for adverse events. METHODS: We conducted a retrospective review of patients with CPM treated by CRS and HIPEC at a single institution between 2000 and 2021. RESULTS: A total of 555 patients were included, of whom 480 (86.5%) had complete cytoreduction, with a median age of 59 years and median Peritoneal Cancer Index (PCI) of 6. Following complete cytoreduction, 5-year overall survival (OS) and disease-free survival (DFS) were 51% and 31%, respectively. In multivariable Cox regression, PCI >6 (hazard ratio [HR] 2.25), pathological node positivity (pN+; HR 1.94), and perineural invasion (HR 1.85) were associated with decreased OS, while PCI >6, pN+, and previous systemic metastases resulted in reduced DFS. Overall, 284 (62%) patients developed recurrence, of whom 97 (34%) had local recurrence (LR), 100 (35%) had systemic recurrence (SR), and 87 (31%) had combined recurrence (5-year OS: 49.3%, 46%, and 37.4%, respectively). Mutated KRAS (mKRAS) was associated with lower 5-year OS (55.8%) and DFS (27.9%) compared with wild-type KRAS (wtKRAS; 70.7% and 37.6%, respectively). In multivariable analyses, mKRAS was related to decreased OS (HR 1.82), DFS (HR 1.55), and SR (OS 1.89), but not to LR. CONCLUSIONS: Complete cytoreduction results in good survival outcomes for patients with CPM. Burden of peritoneal disease and tumor biology are the main predictors of survival. Patients with mKRAS are a high-risk cohort, with increased probability of SR and reduced survival.