BACKGROUND AND PURPOSE: To develop a normal tissue complication probability (NTCP) model of radiation-induced biochemical hypothyroidism (HT) after primary radiotherapy for head and neck squamous cell carcinoma (HNSCC) with adjustment for latency and clinical risk factors. PATIENTS AND METHODS: Patients with HNSCC receiving definitive radiotherapy with 66-68Gy without surgery were followed up with serial post-treatment thyrotropin (TSH) assessment. HT was defined as TSH >4.0mU/l. Data were analyzed with both a logistic and a mixture model (correcting for latency) to determine risk factors for HT and develop an NTCP model based on mean thyroid dose (MTD) and thyroid volume. RESULTS: 203 patients were included. Median follow-up: 25.1months. Five-year estimated risk of HT was 25.6%. In the mixture model, the only independent risk factors for HT were thyroid volume (cm(3)) (OR=0.75 [95% CI: 0.64-0.85], p<0.001) and MTD (Gy) (OR=1.12 [95% CI: 1.07-1.20], p<0.001). From the mixture NTCP-model individual dose constraints for a 25% risk of HT were 26, 38, 48 and 61Gy for thyroid volumes of 10, 15, 20 and 25cm(3), respectively. CONCLUSIONS: Comparing the logistic and mixture models demonstrates the importance of latent-time correction in NTCP-modeling. Thyroid dose constraints in treatment planning should be individualized based on thyroid volume.
BACKGROUND AND PURPOSE: To develop a normal tissue complication probability (NTCP) model of radiation-induced biochemical hypothyroidism (HT) after primary radiotherapy for head and neck squamous cell carcinoma (HNSCC) with adjustment for latency and clinical risk factors. PATIENTS AND METHODS: Patients with HNSCC receiving definitive radiotherapy with 66-68Gy without surgery were followed up with serial post-treatment thyrotropin (TSH) assessment. HT was defined as TSH >4.0mU/l. Data were analyzed with both a logistic and a mixture model (correcting for latency) to determine risk factors for HT and develop an NTCP model based on mean thyroid dose (MTD) and thyroid volume. RESULTS: 203 patients were included. Median follow-up: 25.1months. Five-year estimated risk of HT was 25.6%. In the mixture model, the only independent risk factors for HT were thyroid volume (cm(3)) (OR=0.75 [95% CI: 0.64-0.85], p<0.001) and MTD (Gy) (OR=1.12 [95% CI: 1.07-1.20], p<0.001). From the mixture NTCP-model individual dose constraints for a 25% risk of HT were 26, 38, 48 and 61Gy for thyroid volumes of 10, 15, 20 and 25cm(3), respectively. CONCLUSIONS: Comparing the logistic and mixture models demonstrates the importance of latent-time correction in NTCP-modeling. Thyroid dose constraints in treatment planning should be individualized based on thyroid volume.
Authors: Arthur Chyan; Josephine Chen; Erin Shugard; Louise Lambert; Jeanne M Quivey; Sue S Yom Journal: Radiat Oncol Date: 2014-12-05 Impact factor: 3.481
Authors: Irene Hazell; Karl Bzdusek; Prashant Kumar; Christian R Hansen; Anders Bertelsen; Jesper G Eriksen; Jørgen Johansen; Carsten Brink Journal: J Appl Clin Med Phys Date: 2016-01-08 Impact factor: 2.102
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