Proposal and Validation of a Basic Progression Scoring System for Patients with Skull Base Chordoma

To propose and further validate a basic progression scoring system for patients with skull base chordoma.

All patients (n = 170) undergoing operation for skull base chordoma were classified randomly into a training (n = 113) or validation set (n = 57). In the training set, adverse factors for progression were analyzed by univariate and multivariate analyses. Significant independent factors were included into the scoring system. Scores for each risk category were allocated 1 point and each protection category 0 point. Three prognostic groups were formed on the basis of total score. The same scoring and grouping dispositions were made in the validation set. Analyses of the differences among the 3 groups in individual sets with regard to recurrence and the comparisons between the corresponding prognostic groups of both sets were all carried out by the Kaplan-Meier method.

In the training set, age, treatment history, preoperative Karnofsky performance scale, pathology, and features on magnetic resonance imaging were all significant independent factors and were included into the scoring system. According to the total score, 3 prognostic groups were formed, group A (0-1 points), group B (2-3 points), and group C (3-4 points), respectively. The pairwise comparisons between every 2 of 3 groups in the training set showed significance with P < 0.001, whereas in validation set, a log-rank test showed significance, P ≤ 0.001 (log-rank test). The comparisons between the corresponding prognostic groups of both sets did not show significance.

The basic progression scoring system for patients with skull base chordoma is valid and reproducible.