Tingting Zhang1, Meng Xu1, Jinglin Mi1, Hui Yang2, Zhengchun Liu3, Lulu Huang1, Kai Hu1, Rensheng Wang1. 1. Department of Radiation Oncology, The First Affiliated Hospital of Guangxi Medical University, Nanning, China. 2. Department of Oncology, Liuzhou Worker Hospital, Liuzhou, China. 3. Department of Radiotherapy, Affiliated Hospital of Guilin Medical University, Guilin, China.
Abstract
OBJECTIVE: Whether the original dosimetric constraints of neuro-optic structures (NOS) are appropriate for patients with nasopharyngeal carcinoma (NPC) undergoing intensity-modulated radiotherapy (IMRT) remains controversial. The present study compared the survival rates and radiation-induced optic neuropathy (RION) occurrence between T4 NPC patients whose NOS were irradiated with a near maximum dose received by 2% of the volume (D2%) >55 Gy and ≤55 Gy. Moreover, the NOS dosimetric parameters and their correlation with RION occurrence were also evaluated. METHODS: In this retrospective study, 256 T4 NPC patients treated with IMRT between May 2009 and December 2013 were included. Patient characteristics, survival rates, dosimetric parameters, and RION incidence were compared between the D2% ≤55 Gy and D2% >55 Gy groups. RESULTS: The median follow-up durations were 87 and 83 months for patients in the D2% >55 Gy and D2% ≤55 Gy groups, respectively. The 5-year local recurrence-free survival rates were 92.0 and 84.0% in the D2% >55 Gy and D2% ≤55 Gy groups (P = 0.043), respectively. There was no significant difference in the 5-year overall survival (OS) between both groups (D2% >55 Gy, 81.6%; D2% ≤55 Gy, 79.4%; P = 0.586). No patients developed severe RION (Grades 3-5), and there was no significant difference (P = 0.958) in the incidence of RION between the two groups. The maximum dose of NOS significantly affected the RION incidence, with a cutoff point of 70.77 Gy. CONCLUSION: Appropriately loosening NOS dosimetric constraints in order to ensure a more sufficient dose to the target volume can provide a better 5-year local recurrence-free survival and acceptable neuro-optic toxicity in T4 NPC patients undergoing IMRT.
OBJECTIVE: Whether the original dosimetric constraints of neuro-optic structures (NOS) are appropriate for patients with nasopharyngeal carcinoma (NPC) undergoing intensity-modulated radiotherapy (IMRT) remains controversial. The present study compared the survival rates and radiation-induced optic neuropathy (RION) occurrence between T4 NPC patients whose NOS were irradiated with a near maximum dose received by 2% of the volume (D2%) >55 Gy and ≤55 Gy. Moreover, the NOS dosimetric parameters and their correlation with RION occurrence were also evaluated. METHODS: In this retrospective study, 256 T4 NPC patients treated with IMRT between May 2009 and December 2013 were included. Patient characteristics, survival rates, dosimetric parameters, and RION incidence were compared between the D2% ≤55 Gy and D2% >55 Gy groups. RESULTS: The median follow-up durations were 87 and 83 months for patients in the D2% >55 Gy and D2% ≤55 Gy groups, respectively. The 5-year local recurrence-free survival rates were 92.0 and 84.0% in the D2% >55 Gy and D2% ≤55 Gy groups (P = 0.043), respectively. There was no significant difference in the 5-year overall survival (OS) between both groups (D2% >55 Gy, 81.6%; D2% ≤55 Gy, 79.4%; P = 0.586). No patients developed severe RION (Grades 3-5), and there was no significant difference (P = 0.958) in the incidence of RION between the two groups. The maximum dose of NOS significantly affected the RION incidence, with a cutoff point of 70.77 Gy. CONCLUSION: Appropriately loosening NOS dosimetric constraints in order to ensure a more sufficient dose to the target volume can provide a better 5-year local recurrence-free survival and acceptable neuro-optic toxicity in T4 NPC patients undergoing IMRT.
Authors: B Emami; J Lyman; A Brown; L Coia; M Goitein; J E Munzenrider; B Shank; L J Solin; M Wesson Journal: Int J Radiat Oncol Biol Phys Date: 1991-05-15 Impact factor: 7.038
Authors: Charlotte L Brouwer; Roel J H M Steenbakkers; Jean Bourhis; Wilfried Budach; Cai Grau; Vincent Grégoire; Marcel van Herk; Anne Lee; Philippe Maingon; Chris Nutting; Brian O'Sullivan; Sandro V Porceddu; David I Rosenthal; Nanna M Sijtsema; Johannes A Langendijk Journal: Radiother Oncol Date: 2015-08-13 Impact factor: 6.280
Authors: Fréderic Duprez; Indira Madani; Lieve Morbée; Katrien Bonte; Philippe Deron; Vilmos Domján; Tom Boterberg; Werner De Gersem; Wilfried De Neve Journal: Int J Radiat Oncol Biol Phys Date: 2011-10-24 Impact factor: 7.038
Authors: Piet Dirix; Sandra Nuyts; Bianca Vanstraelen; An Nulens; Robert Hermans; Mark Jorissen; Vincent Vander Poorten; Walter Van den Bogaert Journal: Radiother Oncol Date: 2007-10-25 Impact factor: 6.280