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

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

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

Results: 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.

Conclusions: 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.