Validation of Four Prognostic Models for Metastatic Posterior Uveal Melanoma in a Danish Cohort

PURPOSE: The purpose of this study was to validate the four prognostic models in patients with metastatic posterior uveal melanoma: (I) the American Joint Committee on Cancer (AJCC) staging system, (II) the Helsinki University Hospital Working Formulation (HUHWF), and two nomograms (III) the Valpione-nomogram, and (IV) the Mariani-nomogram.

METHODS: One hundred fifty-two patients with metastatic posterior uveal melanoma were retrospectively included. Dictated by data availability, five subcohorts were established: AJCC (n = 152), HUHWF (n = 93), Valpione-nomogram (n = 92), Mariani-nomogram (n = 68), and a complete dataset subcohort (n = 64). The predictive performance was evaluated with time-dependent Brier-score, calibration plots, receiver operating characteristic (ROC) curves, and the global Harrell's C-index.

RESULTS: The 6-month area under the ROC curve (AUC) was between 0.83 and 0.87 for, respectively, the Mariani-nomogram, the HUHWF, and the Valpione-nomogram, and was 0.77 for the AJCC staging system. The 24-month AUC was 0.81 for the Mariani-nomogram, compared with 0.79 (Valpione-nomogram), 0.74 (HUHWF), and 0.64 (AJCC). The C-index was 0.69 for the Mariani-nomogram, 0.71 for the Valpione-nomogram, and 0.73 for HUHWF (not calculated for AJCC). The accuracy of the prediction models, represented by the Brier score, was after 6 months and 24 months: 0.08 and 0.13 for the Mariani-nomogram, 0.10 and 0.17 for the Valpione-nomogram, 0.10 and 0.14 for the HUHWF, and 0.15 and 0.14 for the AJCC staging system.

CONCLUSIONS: All four models demonstrated an acceptable predictive performance at 6 and 24 months. The Mariani-nomogram appears to perform well across most metrics, often showing the highest values for AUC and the lowest Brier scores.