Validation of the Graded Prognostic Assessment for Melanoma Using Molecular Markers (Melanoma-molGPA)

Abstract

Background: It has been suggested to replace the diagnosis-specific graded prognostic assessment (DS-GPA, based on performance status and number of brain metastases) for patients with primary malignant melanoma with the new Melanoma-molGPA. The latter is a more complex assessment, which also includes BRAF mutation status, age and extracranial metastases. To test the performance of the Melanoma-molGPA, we performed a validation study of this new survival prediction tool.

Methods: A retrospective analysis of patients treated at two different academic institutions was performed. The four-tiered Melanoma-molGPA was calculated as suggested in the original study.

Results: Median overall survival was 5.4 months (95% confidence interval: 3.1 - 7.7 months). Median survival in the four prognostic classes was 2.1, 7.8, 11.8, and 18.0 months, respectively. The 1-year survival rates were 3%, 25%, 43%, and 80%, respectively. The difference between the Kaplan-Meier curves was significant (P = 0.0001, log-rank test).

Conclusions: The present survival outcomes support the use of the Melanoma-molGPA. However, survival was better in each of the four groups in the original study. Possible reasons include lead-time bias and different treatment policies.

Keywords: Brain metastases; Melanoma; Prognostic score; Radiosurgery; Radiotherapy.

Figure 1

Kaplan-Meier curves for overall survival: molGPA 4.0 (3.5 - 4 points, n = 6) vs. molGPA 3.0 (2.5 - 3 points, n = 7) vs. molGPA 2.0 (1.5 - 2 points, n = 23) and molGPA 1.0 (0 - 1 points, n = 33), P = 0.0001 (pooled over all strata).