Background: Aggressive therapeutic regimens have been advocated for the treatment of peritoneal carcinomatosis from colorectal cancer. It is essential to understand the clinical and histological features that govern the natural history of this condition if the efficacies of novel therapeutic approaches are to be assessed adequately.
Methods: A database of 3019 colorectal cancers was used to identify patients with synchronous peritoneal carcinomatosis, patients who developed metachronous peritoneal carcinomatosis, and those without carcinomatosis. Clinical, histological and survival data for the groups were collated and subjected to statistical analysis.
Results: Some 349 patients (13 per cent) with peritoneal carcinomatosis were identified; 214 had synchronous disease and 135 had metachronous carcinomatosis. Some 125 patients (58 per cent) in the synchronous group were free of systemic metastases; 80 of these patients had localized disease. Liver metastases, tumour (T) stage, nodal stage, and venous and perineural invasion were independent predictors of metachronous carcinomatosis. The median survival of patients with synchronous disease was 7 months; survival was adversely affected by the extent of peritoneal carcinomatosis and the T stage of the primary cancer.
Conclusion: Peritoneal carcinomatosis is a common mode of disease progression in patients with colorectal cancer. For the majority of patients the prognosis is poor, but a small number with localized disease may be suitable for further aggressive therapy.