Mohamed El-Shebiney1, Nehal El-Mashad2, Wael El-Mashad3, Ahmed A El-Ebiary4, Abdallah E Kotkat5. 1. Clinical Oncology Department, Faculty of Medicine, Tanta University Hospital, Egypt. 2. Clinical Oncology Department, Faculty of Medicine, Tanta University Hospital, Egypt. Electronic address: nehal.elmashad@med.tanta.edu.eg. 3. Physiology Department, Faculty of Medicine, Tanta University Hospital, Egypt. 4. Forensic Medicine and Clinical Toxicology Departement, Faculty of Medicine, Tanta University Hospital, Egypt. 5. Medical Physics Specialist & RSO, Faculty of Medicine, Tanta University Hospital, Egypt.
Abstract
PURPOSE: The purpose of this study is to determine radiotherapy (RT) dose-volumetric threshold of radiation-induced hypothyroidism (HT) in head and neck squamous cell carcinoma (HNSCC) patients. PATIENTS AND METHODS: The diagnosis of HT in 78 HNSCC patients treated with RT was based on a thyroid stimulating hormone (TSH) level greater than the maximum value of laboratory range. In all patients, dose-volumetric parameters were analyzed according to their relation to development of HT, and thyroid volumes spared from doses ≥10, 20, 30, 40 and 50 Gy (V10, V20, V30, V40 and V50) were analyzed from the dose volume histograms (DVHs). RESULTS: Median follow-up duration was 31 months. At the end of study, 33 patients (42.3%) developed HT and the cumulative incidence of HT was 24.6%, 36.5% and 42.3% at one, two and three years, respectively. V30 of 42.1% (P = 0.005) was defined as dose-volumetric threshold of radiation-induced HT in HNSCC patients. Our analysis showed that V30 separates patients into low- and high-risk groups; the incidence of radiation-induced HT in the group with V30 < 42.1% and V30 ≥ 42.1% was 29.4% and 71.4%, respectively (P = 0.002). CONCLUSIONS: The V30 may predict risk of developing HT after RT for HNSCC patients. V30 of 42.1%, defined as dose-volumetric threshold of radiation-induced HT, can be useful in treatment planning of HNSCC patients.
PURPOSE: The purpose of this study is to determine radiotherapy (RT) dose-volumetric threshold of radiation-induced hypothyroidism (HT) in head and neck squamous cell carcinoma (HNSCC) patients. PATIENTS AND METHODS: The diagnosis of HT in 78 HNSCCpatients treated with RT was based on a thyroid stimulating hormone (TSH) level greater than the maximum value of laboratory range. In all patients, dose-volumetric parameters were analyzed according to their relation to development of HT, and thyroid volumes spared from doses ≥10, 20, 30, 40 and 50 Gy (V10, V20, V30, V40 and V50) were analyzed from the dose volume histograms (DVHs). RESULTS: Median follow-up duration was 31 months. At the end of study, 33 patients (42.3%) developed HT and the cumulative incidence of HT was 24.6%, 36.5% and 42.3% at one, two and three years, respectively. V30 of 42.1% (P = 0.005) was defined as dose-volumetric threshold of radiation-induced HT in HNSCCpatients. Our analysis showed that V30 separates patients into low- and high-risk groups; the incidence of radiation-induced HT in the group with V30 < 42.1% and V30 ≥ 42.1% was 29.4% and 71.4%, respectively (P = 0.002). CONCLUSIONS: The V30 may predict risk of developing HT after RT for HNSCCpatients. V30 of 42.1%, defined as dose-volumetric threshold of radiation-induced HT, can be useful in treatment planning of HNSCCpatients.
Authors: James C H Chow; Ka-Man Cheung; Gavin T C Cheung; Anthony H P Tam; Jeffrey C F Lui; Francis K H Lee; Kwok-Hung Au; Wai-Tong Ng; Anne W M Lee; Harry H Y Yiu Journal: Clin Transl Radiat Oncol Date: 2022-01-24