A prognostic model and staging for metastatic uveal melanoma

Abstract

Background: To identify factors that independently contribute to overall survival in Stage IVB uveal melanoma and to subcategorize by prognosis.

Methods: Data of 91 consecutive patients who died of metastatic uveal melanoma in 1985-2000 were analyzed by Kaplan-Meier and Cox regression analysis. Main covariates were participation in annual review, symptoms, Karnofsky index, metastatic burden, liver function tests, and age. Time on chemotherapy was modeled as a confounder. A working formulation for staging patients according to predicted survival was designed.

Results: Of the 91 patients, 85% underwent annual liver imaging and function tests, 63% were asymptomatic, and 73% received chemotherapy. The median survival period was 8.4 months (95% confidence interval [CI], 6.3-11.8). Karnofsky index, largest dimension of the largest metastasis, metastatic burden, serum transaminase, lactate dehydrogenase, and alkaline phosphatase (AP) levels, and time on chemotherapy were strongly (P < 0.001) associated with survival. Symptoms (P = 0.031) and regular review (P = 0.081) were weakly associated with survival. Karnofsky index (P = 0.013), the largest dimension of the largest metastasis (P = 0.003), and serum AP level (P = 0.042) retained independent significance, adjusting for time on chemotherapy. Predicted median survival calculated for relevant covariate combinations was divided into three periods (> or =12 months vs. 6-11 months vs. < 6 months). Observed median survival for Stage IVBa was 14.9 months (95% CI, 11.7-21.3), for Stage IVBb 8.9 months (95% CI, 2.7-13.7), and for Stage IVBc 2.0 months (95% CI, 1.0-3.7).

Conclusion: The model and working formulation for categorization can be tested as an aid in patient counseling and as a tool in design and analysis of clinical trials.