Combined peritoneal and liver metastases in colorectal cancer: A Dutch nationwide population-based analysis of incidence, treatment and survival

Introduction: The aim of this study was to determine the incidence, treatment patterns, survival and factors associated with curative treatment in colorectal cancer patients with combined liver and peritoneal metastases using Dutch population-based data. Materials and methods: Data from the Netherlands Cancer Registry were used. All patients diagnosed with synchronous isolated peritoneal and liver metastasized colorectal adenocarcinoma between January 1, 2015 and December 31, 2021 were included. Multivariable regression analyses were performed to identify factors associated with receiving curative treatment. Survival rates were calculated for patients undergoing palliative and curative treatment separately. Results: Of 14627 patients with colorectal adenocarcinoma in the study period, 927 patients (6.3 %) had isolated liver and peritoneal metastases and were evaluated in this study. Mean age was 66.9 years, non-mucinous and non-signet-ring cell adenocarcinomas were most prevalent (89.0 %) and tumors were mostly located in the colon (92.1 %). Patients were treated with best supportive care (n = 254, 27,4 %), palliative treatment (n = 618, 66,7 %) or curative treatment (n = 55, 5,9 %). Median OS was 1.5 months, 11.3 months, and 32.6 months, respectively. Multivariable analysis showed that younger age (OR 0.95, p < 0.001) and up to 3 liver metastases (OR 0.13, p < 0.001) are positively associated with receiving curative treatment. Conclusion: This population-based study provides a comprehensive overview of the incidence and treatment of patients with synchronous colorectal liver and peritoneal metastases. It shows that in a highly selected group of patients, curative treatment is associated with better overall survival.