Proposal for a clinical classification of liver metastases.

The lack of a worldwide-accepted classification of liver metastases makes it difficult to compare data on natural history and results from different treatments. The increasing interest in aggressive multimodal therapies for hepatic metastases prompted us to review the chief prognostic factors and the main published classifications in order to propose a new clinical classification, whose principal application concerns metastases from colorectal adenocarcinomas. Following the general rules of the TNM classification, liver metastases are classified by expressing with letters and numbers the parameters selected for their prognostic importance, clinical applicability and objectivity. H (hepatic) is the letter that indicates the liver is the site of metastasis. Synchronous metastases are indicated by H, metachronous by rH (r = recurrent). The extent of liver involvement is defined: H1, liver involvement less than 25%; H2, from 25 to 50%; H3, more than 50%. Site of metastases is defined by s (single), m (multiple to one surgical lobe), b (to both lobes), i (infiltration of important structures). The alteration of liver functions is indicated by F. The presence of cirrhosis is noted by C.