A single-institution validation of the AJCC staging system for stage IV melanoma

Survival of patients with stage IV melanoma is poor. In the current American Joint Committee on Cancer (AJCC) staging system, site of distant disease and lactate dehydrogenase (LDH) are the only prognostic factors included for stage IV disease. We sought to validate the current AJCC staging system in a contemporary, prospectively collected cohort of patients and explore additional factors that may influence prognosis.

Our prospective database was searched to identify patients with stage IV melanoma; only patients seen at our institution before developing stage IV disease were included (n = 589). Demographic, clinical, and tumor characteristics were abstracted. Univariate and multivariate assessment of prognostic factors associated with survival were performed by Cox regression.

Overall median survival was 9 months. Differential survival by AJCC substage was observed (P < .001). For each site of disease described within the AJCC staging system, an abnormal LDH level was associated with a poorer prognosis. By multivariate analysis, older age at diagnosis (as a continuous variable, hazard ratio [HR] 1.02, 95% confidence interval [95% CI]) 1.01-1.02), an abnormal LDH (HR 1.42, 95% CI 1.11-1.82), site of disease (lung HR 1.22, 95% CI .89-1.66; other viscera 1.61, 95% CI 1.18-2.21), more than one organ involvement (HR 1.27, 95% CI 1.01-1.60), and more than one metastasis (HR 2.27, 95% CI 1.65-3.14) were independently associated with poorer survival. Sex, antecedent stage, and disease-free interval were not statistically significant.

In our patient cohort, the AJCC staging system was valid. The strongest predictor of survival-the number of metastases present at the diagnosis of stage IV disease-represents a variable to consider in future staging systems.