Toxicity and dosimetric analysis of nasopharyngeal carcinoma patients undergoing radiotherapy with IMRT or VMAT: A regional center's experience

Ling He; Jianghong Xiao; Zhigong Wei; Yan He; Jingjing Wang; Hui Guan; Xiaoli Mu; Xingchen Peng

doi:10.1016/j.oraloncology.2020.104978

Toxicity and dosimetric analysis of nasopharyngeal carcinoma patients undergoing radiotherapy with IMRT or VMAT: A regional center's experience

Oral Oncol. 2020 Aug 27:109:104978. doi: 10.1016/j.oraloncology.2020.104978. Online ahead of print.

Authors

Ling He¹, Jianghong Xiao², Zhigong Wei¹, Yan He¹, Jingjing Wang¹, Hui Guan¹, Xiaoli Mu¹, Xingchen Peng³

Affiliations

¹ Department of Biotherapy, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
² Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
³ Department of Biotherapy, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China. Electronic address: pxx2014@scu.edu.cn.

PMID: 32861986
DOI: 10.1016/j.oraloncology.2020.104978

Abstract

Objectives: To observe the differences of dosimetric parameters and late toxicities in Nasopharyngeal Carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT), which may provide the selective basis about radiation technology in clinical practices.

Methods and materials: Dosimetric parameters and late toxicities were collected and retrospectively analyzed from 627 NPC patients (stage as I-IVA/IVB) between January 2010 and December 2015.

Results: The median D₂ of all targets and D₅₀ of PGTVnd (regional lymph nodes) were lower in VAMT than those in IMRT, while the median D₉₅ and D₉₈ of PGTVnx (primary lesions) were higher in VMAT than those in IMRT (p < 0.05). Superior sparing of the organs at risk were observed in VMAT. The maximum dose of the brainstem, spinal cord, temporal lobes, temporomandibular joint, optic chiasm, and lens were lower in VMAT than those in IMRT, where the median dose reduction ranged from 0.56 to 3.56 Gy (p < 0.05). Meanwhile, the median parotid glands V₃₀ in VMAT was reduced by approximately 2% compared to that in IMRT (p = 0.027). Regarding the late toxicities, ototoxicity, trismus, and temporal lobe injury were reduced by VMAT (p < 0.05). Furthermore, the late toxicities were correlative with the radiation dose of the corresponding OARs (p < 0.05).

Conclusion: For NPC treatment plans, the VMAT might provide not only more favorable dose distributions of targets but also better sparing of normal tissue than observed in IMRT. Furthermore, VMAT possibly provides less treatment-related late toxicities such as ototoxicity, trismus, and temporal lobe injury.

Keywords: Dosimetry; Intensity-modulated radiation therapy; Late toxicities; Nasopharyngeal carcinoma; Volumetric modulated arc therapy.