Plasma uric acid and tumor volume are highly predictive of outcome in nasopharyngeal carcinoma patients receiving intensity modulated radiotherapy

Abstract

Background: The combined predictive value of plasma uric acid and primary tumor volume in nasopharyngeal carcinoma (NPC) patients receiving intensity modulated radiation therapy (IMRT) has not yet been determined.

Methods: In this retrospective study, plasma uric acid level was measured after treatment in 130 histologically-proven NPC patients treated with IMRT. Tumor volume was calculated from treatment planning CT scans. Overall (OS), progression-free (PFS) and distant metastasis-free (DMFS) survival were compared using Kaplan-Meier analysis and the log rank test, and Cox multivariate and univariate regression models were created.

Results: Patients with a small tumor volume (<27 mL) had a significantly better DMFS, PFS and OS than patients with a large tumor volume. Patients with a high post-treatment plasma uric acid level (>301 μmol/L) had a better DMFS, PFS and OS than patients with a low post-treatment plasma uric acid level. Patients with a small tumor volume and high post-treatment plasma uric acid level had a favorable prognosis compared to patients with a large tumor volume and low post-treatment plasma uric acid level (7-year overall OS, 100% vs. 48.7%, P <0.001 and PFS, 100% vs. 69.5%, P <0.001).

Conclusions: Post-treatment plasma uric acid level and pre-treatment tumor volume have predictive value for outcome in NPC patients receiving IMRT. NPC patients with a large tumor volume and low post-treatment plasma uric acid level may benefit from additional aggressive treatment after IMRT.

Figure 1

Kaplan-Meier overall survival, progression-free survival and distant metastasis-free survival curves for 130 nasopharyngeal cancer patients treated with IMRT stratified by pre-treatment primary tumor volume.

Figure 2

Kaplan-Meier overall survival, progression-free survival and distant metastasis-free survival curves for 130 nasopharyngeal cancer patients treated with IMRT stratified by post-treatment plasma uric acid level.

Figure 3

Kaplan-Meier overall survival, progression-free survival and distant metastasis-free survival for 130 nasopharyngeal cancer patients treated with IMRT, stratified according a combination of pre-treatment primary tumor volume (TV) and post-treatment plasma uric acid (UA). S-TV/H-UA indicates a small tumor volume (< 27 mL) and high post-treatment plasma uric acid level (>301 μmol/L); L-TV/L-UA indicates a large tumor volume (≥ 27 mL) and low post-treatment plasma uric acid level (≤301 μmol/L).