A new classification system for liver metastases from colorectal cancer in Japanese multicenter analysis

Although numerous authors have reported various prognostic factors for liver metastases from colorectal cancer, there is not yet a general classification.

A total of 478 colorectal cancer patients from 18 institutes were studied. Prognostic factors were investigated using univariate and multivariate analyses.

Independent prognostic factors for colorectal liver metastases were number of liver metastases, size of the largest liver metastases, mesenteric lymph node metastases (pN0/1: < or =3 lesions, pN2: > or =4 lesions), and extrahepatic metastases (EM0: absence of extrahepatic metastasis, EM1: presence of extrahepatic metastases). We defined the following classification system; Stage A: HT1 (< or =4 lesions and < or =5cm) and pN0/1, Stage B: HT2 (> or =5 lesions or >5cm) and pN0/1, or HT1 and pN2, Stage C: HT2 and pN2, HT3 (> or =5 lesions and >5cm) with any pN, or any HT and any pN with EM1. Five-year survival rates were 53.5% for Stage A patients, 25.4% for Stage B patients, and 5.8% for Stage C patients. Median survival time was 70.4 months, 31.4 months, and 17.2 months, respectively.

Our classification was advocated to evaluate prognoses for liver metastases from colorectal cancer. It can help guide decision making in terms of liver resection and assessing patient prognosis.