A prognostic scoring system for locoregional control in nasopharyngeal carcinoma following conformal radiotherapy

Purpose: This study established a prognostic scoring system for nasopharyngeal carcinoma (NPC), which estimates the probability of locoregional (LR) control following definitive conformal radiotherapy.

Methods and Materials: Patients with nondisseminated NPC at initial presentation (n = 630) were enrolled in this study. All patients had magnetic resonance imaging of the head and neck and were treated with conformal radiotherapy. Among them, 93% had concurrent chemotherapy, and 76% had postradiation chemotherapy. The extent of the primary tumor, age at diagnosis, primary tumor size, tumor and nodal classification, histology, and serum lactate dehydrogenase (LDH) level before treatment were included in the analysis for building a prognostic scoring system. The end point for this study was LR control.

Results: The prognostic score was defined as the number of adverse prognostic factors present at diagnosis. Four factors had similarly independent prognostic effects (hazard ratio, 2.0–2.6): age >40 years, histologic WHO type I-II, serum LDH level ≥410 U/L, and involvement of two or more sites of the following anatomic structures, i.e., sphenoid floor, clivus marrow, clivus cortex, prevertebral muscles, and petrous bone. The score predicted the 5-year probability of LR control as follows: 0 (15% of the patients), 100%; 1 (42% of the patients), 93%; 2 (29% of the patients), 83%; 3 or higher (13% of the patients), 71%.

Conclusion: This scoring system is useful in the decision-making for individual patients and the design of clinical trials to improve LR control for advanced-stage NPC.

Keywords: Nasopharyngeal carcinoma, Radiotherapy, Prediction model, Prognostic score, Locoregional control