Prognostic similarities and differences in optimally resected liver metastases and peritoneal metastases from colorectal cancers

To analyze and compare survival in patients operated for colorectal liver metastases (LM) with that in patients optimally resected for peritoneal metastases (PM).

This study concerns 287 patients with LM and 119 patients with PM treated with surgery plus chemotherapy between 1993 and 2009, excluding patients presenting both LM and PM.

Mortality (respectively, 2.7% and 4.2%), morbidity (respectively, 11% and 17%), and 5-year overall survival (OS) rates (respectively, 38.5% and 36.5%) were not statistically different between the LM group and the PM group. Multivariate analysis showed that the extent of the disease was the main prognostic factor, which led us to divide the population into 5 subgroups. The best 5-year OS rate (72.4%) was obtained in patients with minimal peritoneal disease [peritoneal cancer index (PCI) ≤5]. OS was similar for the patients with less than 10 LM and those with a PCI between 6 and 15 (respectively, 39.4% and 38.7%). Five-year OS was lower in patients with more than 10 LM (18.1%), and dramatically low for patients with a PCI > 15 (11.8%).

This study underlines the prognostic impact of the tumor burden in metastatic colorectal disease. In selected patients, similar survival rates can be obtained after optimal treatment of LM and PM. As the role of optimal surgical resection of LM is widely accepted, our results confirm that an optimal attitude should also be adopted to treat PM with a PCI < 16, particularly in patients with very low PCI (<5) where survival could be better than LM.