Pre-treatment amide proton transfer imaging predicts treatment outcome in nasopharyngeal carcinoma

Abstract

Objective: To investigate the value of pre-treatment amide proton transfer-weighted (APTw) imaging for predicting survival of patients with nasopharyngeal carcinoma (NPC).

Materials and methods: Pre-treatment APTw imaging was performed in 77 NPC patients and the mean, 90th percentile, skewness, and kurtosis of APT asymmetry (APT_mean, APT₉₀, APT_skewness, and APT_kurtosis, respectively) were obtained from the primary tumor. Associations of APTw parameters with locoregional relapse-free survival (LRRFS), distant metastasis-free survival (DMFS), and disease-free survival (DFS) after 2 years were assessed by univariable Cox regression analysis and significant APTw parameters, together with age, sex, treatment, and stage as confounding variables, were added to the multivariable model. Kaplan-Meier analysis was used to determine the prognostic significance of patients with high or low APT values based on a threshold value from receiver operating characteristic curve analysis.

Results: Locoregional relapse, distant metastases, and disease relapse occurred in 14/77 (18%), 10/77 (13%), and 20/77 (26%) patients, respectively, at a median follow-up of 48.3 (10.6-67.4) months. Univariable analysis showed significant associations of LRRFS with APT_skewness (HR = 1.98; p = 0.034), DMFS with APT_mean (HR = 2.44; p = 0.033), and APT₉₀ (HR = 1.93; p = 0.009), and DFS with APT_mean (HR = 2.01; p = 0.016), APT₉₀ (HR = 1.68; p = 0.009), and APT_skewness (HR = 1.85; p = 0.029). In multivariable analysis, the significant predictors for DMFS were APT₉₀ (HR = 3.51; p = 0.004) and nodal stage (HR = 5.95; p = 0.034) and for DFS were APT₉₀ (HR = 1.97; p = 0.010) and age (HR = 0.92; p = 0.014). An APT₉₀ ≥ 4.38% was associated with a significantly poorer DFS at 2 years than APT₉₀ < 4.38% (66% vs. 91%; HR = 4.01; p = 0.005).

Conclusion: APTw imaging may potentially predict survival in patients with NPC.

Key points: • APTw imaging may provide new markers to predict survival in nasopharyngeal carcinoma. • APT₉₀ is an independent predictor of distant metastases-free survival and disease-free survival. • The APT_high group is at higher risk of disease relapse than the APT_low group.

Keywords: Amide proton transfer; Disease-free survival; Head and neck cancer; Nasopharyngeal carcinoma; Treatment outcome.