Which T Category of Nasopharyngeal Carcinoma May Benefit Most from Volumetric Modulated Arc Therapy Compared with Step and Shoot Intensity Modulated Radiation Therapy.

Sun, Ying; Guo, Rui; Yin, Wen-Jing; Tang, Ling-Long; Yu, Xiao-Li; Chen, Mo; Qi, Zhen-Yu; Liu, Meng-Zhong; Ma, Jun

Background:To compare volumetric modulated arc therapy (VMAT) with conventional step and shoot intensity modulated radiation therapy (s-IMRT) in nasopharyngeal carcinoma (NPC) patients, and identify which T category patient gains the maximum benefit from VMAT. Methods:Fifty-two patients that randomly selected from 205 patients received VMAT at a single center were retrospectively replanned with s-IMRT. For a fair comparison, the planning target volume (PTV) coverage of the 2 plans was normalized to the same level. A standard planning constraint set was used; the constraints for the organs at risk (OARs) were individually adapted. The calculated doses to the PTV and OARs were compared for s-IMRT and VMAT plans generated using the Monaco treatment planning system. Results:VMAT and s-IMRT plans had similar PTV coverage and OAR sparing within all T categories. However, in stratified analysis, VMAT plans lead to better or similar sparing of the OARs in early T category patients; and lead to poorer sparing of the OARs in advanced T category patients (Pp<0.01). Conclusions:VMAT provides similar dose coverage of the PTVs and similar/better normal tissue sparing in early T category NPC, and poorer OARs sparing in advanced T category NPC. And VMAT shows significant advantages for low dose burden and delivery time.

NASOPHARYNX cancer; COMPARATIVE studies; INTENSITY modulated radiotherapy; CANCER radiotherapy; RETROSPECTIVE studies; DRUG delivery systems; CANCER treatment

PLoS ONE, 2013, Vol 8, Issue 9, p1

1932-6203

Academic Journal

10.1371/journal.pone.0075304