J Cancer 2020; 11(17):5210-5222. doi:10.7150/jca.45767

Research Paper

Different Risk Target Volumes for Nasopharyngeal Carcinoma Treated with Simultaneous Integrated Boost Intensity-Modulated Radiotherapy

Fangzheng Wang1,2,3,4✉, Chuner Jiang1,5,6,*, Lei Wang1,2,3,4, Fengqin Yan1,2,3,4, Yongfeng Piao1,2,3,4, Zhimin Ye1,2,3,4, Min Xu1,5,6, Jiping Liu1,5,6, Zhenfu Fu1,2,3,4✉, Yangming Jiang7

1. Department of Radiation Oncology, Cancer Hospital of the University of Chinese Academy of Sciences, Zhejiang Hangzhou 310022, People's Republic of China.
2. Institute of Cancer and Basic Medicine (ICBM), Chinese Academy of Sciences, Zhejiang Hangzhou 310022, People's Republic of China.
3. Department of Radiation Oncology, Zhejiang Cancer Hospital, Zhejiang Hangzhou 310022, People's Republic of China.
4. Key Laboratory of Radiation Oncology of Zhejiang Province, Zhejiang Hangzhou 310022, People's Republic of China.
5. Department of Breast Tumor Surgery, Cancer Hospital of the University of Chinese Academy of Sciences, Zhejiang Hangzhou 310022, People's Republic of China.
6. Department of Breast Tumor Surgery, Zhejiang Cancer Hospital, Zhejiang Hangzhou 310022, People's Republic of China.
7. Department of Digital Earth, Institute of Remote Sensing and Digital Earth, CAS, Beijing, 100101, People's Republic of China.
*These authors have contributed equally to this work.

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Citation:
Wang F, Jiang C, Wang L, Yan F, Piao Y, Ye Z, Xu M, Liu J, Fu Z, Jiang Y. Different Risk Target Volumes for Nasopharyngeal Carcinoma Treated with Simultaneous Integrated Boost Intensity-Modulated Radiotherapy. J Cancer 2020; 11(17):5210-5222. doi:10.7150/jca.45767. Available from https://www.jcancer.org/v11p5210.htm

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Abstract

Background and Objectives: Although intensity-modulated radiotherapy (IMRT) provides promising survival advantages and fewer late complications in patients with nasopharyngeal cancer (NPC), appropriated target volumes and prescribed doses are still being explored. This study aimed to propose different risk target volumes and corresponding prescribed doses in our center and to evaluate the physical basis and efficacy of this protocol based on the long-term survival of NPC patients.

Methods and Materials: We retrospectively assessed patients with histology-proven non-metastatic NPC treated with definitive IMRT using our protocol of different risk target volumes and corresponding prescribed doses based on the orderly stepwise pattern of tumor spread. We described the delineation for different risk target volumes and the design of IMRT planning for an NPC case. Additionally, we compared the dosimetric distributions between the China protocol and our protocol through two NPC cases. The patterns of failure and locoregional control were the primary endpoints. All survival outcomes were calculated using the Kaplan-Meier method.

Results: From January 2013 to December 2014, a total of 335 patients were treated; the median follow-up for patients who survived was 70 months. All patients completed IMRT using our protocol. Twenty-five patients developed locoregional recurrence, and all recurrences occurred within the high-dose target volumes. The rates of locoregional recurrence-free survival, distant metastasis-free survival, progression-free survival, and overall survival at 5 years were 92.2%, 92.1%, 85.9%, and 86.3%, respectively. The biological effective doses of the prescribed doses in our protocol were similar to those of the China and 0615 protocols. Moreover, our protocol offered a reduction in D1 and D2 in the primary gross tumor volume (GTV), while V30 and V40 in normal tissues were lower.

Conclusion: Our protocol of different risk target volume delineations and corresponding prescribed doses based on the stepwise pattern of tumor spread resulted in favorable locoregional control with no relapse outside the GTV.

Keywords: nasopharyngeal carcinoma, IMRT, target volume, dose, long-term survival