Rui-Ping Zhai1, Fang-Fang Kong1, Cheng-Run Du1, Chao-Su Hu1, Hong-Mei Ying2. 1. Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, PR China. 2. Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, PR China. Electronic address: doctoryinghm@163.com.
Abstract
OBJECTIVES: To investigate the rate and risk factors for developing hypothyroidism (HT) in nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT). MATERIALS AND METHODS: A total of 135 consecutive patients treated with IMRT for NPC were prospectively evaluated during a median follow up of 34.1months. Serum thyroid function assessments before and after IMRT were periodically monitored. To identify risk factors for HT occurrence, univariate and multivariate Cox regression analyses were performed. RESULTS: Thirty-nine patients (28.9%) developed primary HT. The 2- and 3-year incidences of primary HT were 29.6% and 43.9%, respectively. The median clinical latency for primary HT was 15.1months (3.2-33.8months). No cases of central HT were observed. Univariate and multivariate analyses revealed that the risk increased with younger age and decreased with higher pretreatment thyroid volume. Patients with thyroid mean dose ≥45Gy had a 4.9 times increased risk of HT than those receiving lower mean dose. Alternatively, the thyroid V45 below 0.5 and V50 below 0.35 were found to significantly lower the incidence rate of HT. CONCLUSION: The incidence of primary HT after IMRT for NPC continued to increase with time. The thyroid mean dose constraint was approximately 45Gy. We recommended plan optimization objectives to reduce thyroid V45 to 0.5 and V50 to 0.35.
OBJECTIVES: To investigate the rate and risk factors for developing hypothyroidism (HT) in nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT). MATERIALS AND METHODS: A total of 135 consecutive patients treated with IMRT for NPC were prospectively evaluated during a median follow up of 34.1months. Serum thyroid function assessments before and after IMRT were periodically monitored. To identify risk factors for HT occurrence, univariate and multivariate Cox regression analyses were performed. RESULTS: Thirty-nine patients (28.9%) developed primary HT. The 2- and 3-year incidences of primary HT were 29.6% and 43.9%, respectively. The median clinical latency for primary HT was 15.1months (3.2-33.8months). No cases of central HT were observed. Univariate and multivariate analyses revealed that the risk increased with younger age and decreased with higher pretreatment thyroid volume. Patients with thyroid mean dose ≥45Gy had a 4.9 times increased risk of HT than those receiving lower mean dose. Alternatively, the thyroid V45 below 0.5 and V50 below 0.35 were found to significantly lower the incidence rate of HT. CONCLUSION: The incidence of primary HT after IMRT for NPC continued to increase with time. The thyroid mean dose constraint was approximately 45Gy. We recommended plan optimization objectives to reduce thyroid V45 to 0.5 and V50 to 0.35.
Authors: Mona Kamal; Christopher Ryan Peeler; Pablo Yepes; Abdallah S R Mohamed; Pierre Blanchard; Steven Frank; Lei Chen; Amit Jethanandani; Rohit Kuruvilla; Benjamin Greiner; Jared Harp; Robin Granberry; Vivek Mehta; Crosby Rock; Katherine Hutcheson; Carlos Cardenas; G Brandon Gunn; Clifton Fuller; Dragan Mirkovic Journal: Adv Radiat Oncol Date: 2019-09-07
Authors: Ren Luo; Vincent W C Wu; Binghui He; Xiaoying Gao; Zhenxi Xu; Dandan Wang; Zhining Yang; Mei Li; Zhixiong Lin Journal: BMC Cancer Date: 2018-05-18 Impact factor: 4.430