Subdividing the M1 stage of liver metastasis for nasopharyngeal carcinoma to better predict metastatic survival

In nasopharyngeal carcinoma (NPC), the M1 stage of the TNM classification does not differentiate between the site of metastasis or the number of metastatic lesions. However, NPC patients with lung or bone metastases survive longer than do those with liver metastasis (LM). We subdivided the M1 stage of LM to better predict survival in these patients. From the records of 305 NPC patients with LM treated at Sun Yat-sen University Cancer Center between January 2000 and December 2007, we determined the effects of clinical characteristics and the subclassifications of the M1 stage for LM characteristics [the number, size, timing (synchronous vs. metachronous), and distribution of metastases and metastases to other organs] on survival since the diagnosis of LM. Metastatic survival rates were 62% at 1 year, 31% at 2 years, and 21% at 3 years. Having 1–3 metastatic lesions, having lesions less than 5 cm in diameter, and having unilobular LM were better univariate predictors of metastatic survival. Better survival was independently predicted by having one to three (vs. more than three) metastatic lesions (hazards ratio = 0.52; 95% CI = 0.33–0.82) and unilobular (vs. bilobular) lesions (hazards ratio = 0.35; 95% CI = 0.22–0.57). The current report constitutes large samples of LM from NPC from our single institution with correlation between LM characteristics and metastatic survival. Patients with NPC and one to three liver metastases or unilobular metastases survive longer than their counterparts, and aggressive treatment should be considered.