J Cancer 2017; 8(5):861-869. doi:10.7150/jca.17957

Research Paper

Magnetic Resonance Imaging-Detected Tumor Residue after Intensity-Modulated Radiation Therapy and its Association with Post-Radiation Plasma Epstein-Barr Virus Deoxyribonucleic Acid in Nasopharyngeal Carcinoma

Jia-Wei Lv1*, Guan-Qun Zhou1*, Jia-Xiang Li2, Ling-Long Tang1, Yan-Ping Mao1, 3, Ai-Hua Lin4, Jun Ma1, Ying Sun1✉

1. Department of Radiation Oncology, Sun Yat-sen University Cancer Center
State Key Laboratory of Oncology in South China
Collaborative Innovation Center for Cancer Medicine, Guangzhou, People's Republic of China
2. Department of Oncology, First People's Hospital of Zhaoqing, Guangdong, People's Republic of China;
3. Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, United States;
4. Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, People's Republic of China.
* Jia-Wei Lv, Guan-Qun Zhou contributed equally to this article.

Abstract

Purpose: To evaluate the prognostic value of magnetic resonance imaging (MRI)-detected tumor residue after intensity-modulated radiation therapy (IMRT) and its association with post-treatment plasma Epstein-Barr virus deoxyribonucleic acid (EBV DNA) in nasopharyngeal carcinoma (NPC).

Methods and materials: A prospective database of patients with histologically-proven NPC was used to retrospectively analyze 664 cases. Pre- and post-treatment MRI scans were independently reviewed by two senior radiologists who were blinded to clinical findings. Factors significantly associated with MRI-detected tumor residue were identified and included in the following multivariate logistic regression model. Residual risk model were established. Receiver operating characteristic (ROC) identify the optimal cut-off risk score for tumor residue.

Results: MRI-detected residual tumor at three months after IMRT was associated with poor prognosis. The 5-year survival rates for the non-residual and residual groups were: OS (93.8% vs. 76.6%, P<0.001), PFS (84.7% vs. 67.9%, P=0.006), LRFS (93.4% vs. 80.4%, P=0.002), and DMFS (90.3% vs. 87.9%, P=0.305), respectively. Three-month post-treatment EBV DNA was significantly associated with tumor residue (P<0.001). A residual risk score model was established, consisting of T and N categories and post-treatment EBV DNA. ROC identified 22.74 as the optimal cut-off risk score for tumor residue. High-risk score was independently associated with poor treatment outcomes.

Conclusions: MRI-detected tumor residue was an independent adverse prognostic factor in NPC; and significantly associated with three-month post-treatment EBV DNA. As limited resources in some endemic areas prevent patients from undergoing routine post-treatment imaging, our study identifies a selection risk-model, providing a cost-effective reference for the selection of follow-up strategies and clinical decision-making.

Keywords: Nasopharyngeal carcinoma, Intensity-modulated radiation therapy, Tumor residue, Magnetic resonance imaging, Plasma EBV DNA

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How to cite this article:
Lv JW, Zhou GQ, Li JX, Tang LL, Mao YP, Lin AH, Ma J, Sun Y. Magnetic Resonance Imaging-Detected Tumor Residue after Intensity-Modulated Radiation Therapy and its Association with Post-Radiation Plasma Epstein-Barr Virus Deoxyribonucleic Acid in Nasopharyngeal Carcinoma. J Cancer 2017; 8(5):861-869. doi:10.7150/jca.17957. Available from http://www.jcancer.org/v08p0861.htm