Dosimetric Predictors of Hypothyroidism After Radical Intensity-modulated Radiation Therapy for Non-metastatic Nasopharyngeal Carcinoma

Lee, V.; Chan, Sum‐Yin; Choi, Cheuk-Wai; Kwong, Dora Lai Wan; Lam, Ka‐On; Tong, Chi-Chung; Sze, Ckh; Ng, S C; Leung, TW; Lee, A.

doi:10.1016/j.clon.2016.05.004

Cited by 40 publications

(74 citation statements)

References 32 publications

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“…This finding is consistent with previous studies reporting that RHT primarily occurred in the first 2-3 years after RT. 24,37 The latency of RHT is shorter when the thyroid gland receives higher doses. 41 Therefore, regular follow-up for thyroid function in the first two years post-RT is particularly important for NPC survivors.…”

Section: Discussionmentioning

confidence: 99%

“…These results are similar to those in patients with NPC from other reports. 16,24,32,38 The median latency of HT was 10.5 months after RT, and 89.5% of patients developed HT within 18 months. This finding is consistent with previous studies reporting that RHT primarily occurred in the first 2-3 years after RT.…”

Section: Discussionmentioning

confidence: 99%

“…10,15 Threedimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) enable the analysis of dose-volume factors. The minimum dose (D min ) and mean dose (D mean ), the percentage of thyroid volume receiving .30, 45 or 50 Gy, the absolute thyroid volume spared from 45 Gy or less and volume spared from 60 Gy or less 13,14,[16][17][18][19][20][21][22][23][24] were found to be dosimetric predictors for RHT. However, predictors and dose constraints varied according to the study.…”

Section: Introductionmentioning

confidence: 99%

“…However, predictors and dose constraints varied according to the study. 13,14,[16][17][18][19][20][21][22][23][24][25] Nasopharyngeal carcinoma (NPC) is a prevalent cancer in southern China. Irradiation to the bilateral neck is a regular practice because of a high incidence 26 of neck node involvement.…”

Section: Introductionmentioning

confidence: 99%

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Nomogram for radiation-induced hypothyroidism prediction in nasopharyngeal carcinoma after treatment

Luo

et al. 2017

The British Journal of Radiology

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The authors Ren Luo and Mei Li contributed equally to this work.Objective: The aim of this study was to develop a nomogram for radiation-induced hypothyroidism (RHT) prediction. Methods: We collected data from 164 patients with nasopharyngeal carcinoma (NPC) in our previous prospective study. Biochemical hypothyroidism was defined as a serum thyroid-stimulating hormone level greater than the normal value. We collected both clinical and dose-volume factors. A univariate Cox regression analysis was performed to identify RHT risk factors. Optimal predictors were selected according to the least absolute shrinkage and selection operator (LASSO). We then selected the Cox regression models that best balanced the prediction performance and practicability to build a nomogram for RHT prediction. Results: There were 38 (23.2%) patients who developed RHT, and the median follow-up was 24 months. The univariate Cox regression analysis indicated that gender, minimum dose, mean dose (D mean ) and V 25 -V 60 [V x (%), the percentage of thyroid volume receiving .x Gy] of the thyroid were significantly associated with RHT. The variables of gender, receiving chemotherapy or not (chemo), D mean and V 50 were selected using the LASSO analysis. A nomogram based on a three-variable (gender, chemo and V 50 ) Cox regression model was constructed, and its concordance index was 0.72. Good accordance between prediction and observation was showed by calibration curves in the probability of RHT at 18, 24 and 30 months. Conclusion: This study built a nomogram for RHT in NPC survivors by analyzing both clinical and dose-volume parameters using LASSO. Thus, the individual dose constraint could be achieved in a visual format. Advances in knowledge: This study used LASSO to more accurately address the multicollinear problem between variables. The resulting nomogram will help physicians predict RHT. INTRODUCTIONRadiation-induced hypothyroidism (RHT) is a common late complication after irradiation to the neck area. The majority of early RHT cases are silent because subclinical hypothyroidism (HT) can be detected only by thyroid hormone tests [elevated serum thyroid-stimulating hormone (TSH) and normal serum free thyroxine (fT4) and/ or serum free triiodothyronine (fT3)]. However, other cases show overt disease [overt hypothyroidism (overt HT)] that presents with elevated TSH and decreased fT4 and/or fT3. The incidence of subclinical HT is 24-50%, and overt HT develops in 6-20% of patients with head and neck cancer who receive radiotherapy (RT).1 HT has been demonstrated to be correlated with the development of cardiovascular and pulmonary disorders in addition to diabetes mellitus, 2-7 which increases the adverse effects of RHT on patient quality of life.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nomogram for radiation-induced hypothyroidism prediction in nasopharyngeal carcinoma after treatment

Luo

et al. 2017

The British Journal of Radiology

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“…Sommat et al reported that thyroid V 40Gy ≤ 85% was a useful dose constraint during IMRT plans without compromising tumor coverage . Lee et al revealed that VS 60Gy (the absolute thyroid volume spared from ≤60 Gy) ≥10 cm 3 and VS 45Gy ≥ 5 cm 3 could lower the risk of HT without compromising target coverage . These dose‐volume thresholds helped clinicians design more appropriate treatment plans.…”

Section: Introductionmentioning

confidence: 99%

Thyroid dose‐volume thresholds for the risk of radiation‐related hypothyroidism in nasopharyngeal carcinoma treated with intensity‐modulated radiotherapy—A single‐institution study

Huang

Tan²,

Guo

et al. 2019

Cancer Medicine

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BackgroundTo identify thyroid dose‐volume thresholds for radiotherapy (RT)‐related hypothyroidism (HT) in patients with nasopharyngeal carcinoma (NPC) treated with intensity‐modulated RT (IMRT). In this way, we desired to guide the design of treatment plans and, finally, lower HT prevalence.MethodsIn total, 345 NPC patients treated with IMRT were evaluated retrospectively during a median follow‐up of 45.2 (range, 11.3‐64.9) months. Serum‐based assessments of thyroid function before and after IMRT were monitored periodically. Thyroid dose‐volume parameters were analyzed for their association with HT risk.ResultsIn total, 44.1% of patients (152/345) developed primary HT. Analyses of thyroid dose‐volume parameters identified a stringent dose‐volume histogram (DVH) threshold defined by V 25Gy (the percentage thyroid volume that receives >25 Gy, not the absolute volume) ≤60%, V 35Gy ≤ 55%, and V 45Gy ≤ 45%. Patients whose thyroid DVHs satisfied these constraints had a lower prevalence of 2‐year HT compared with the overall prevalence (13.2% vs 25.8%, P < .001). Another DVH was defined by V 25Gy > 95%, V 35Gy > 90%, and V 45Gy > 75%, and patients whose thyroid DVHs satisfied with these constraints had a higher prevalence of 2‐year HT than the overall incidence (36.0% vs 25.8%, P < .001).ConclusionWe recommend V 25Gy ≤ 60%, V 35Gy ≤ 55%, and V 45Gy ≤ 45% as the “stringent” DVH line, and V 25Gy > 95%, V 35Gy > 90%, and V 45Gy > 75% as the “inhibition” DVH line, under the precondition of not compromising the target coverage. These findings could help in the design of individual treatment plans and, eventually, to lowering of HT prevalence.

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Risk factors of early thyroid dysfunction after definitive radiotherapy in nasopharyngeal carcinoma patients

et al. 2023

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BackgroundTo explore the patterns and risk factors of early thyroid dysfunction in nasopharyngeal carcinoma (NPC) patients within 1 year after intensity‐modulated radiation therapy (IMRT).MethodsPatients with NPC who received definitive IMRT between April 2016 and April 2020 were included. All patients had normal thyroid function before definitive IMRT. The chi‐square test, Student's T‐test, Mann–Whitney U test, Kaplan–Meier method, receiver operating characteristics curve, and Cox proportional hazard analysis were used for statistical analysis.ResultsA total of 132 NPC patients were identified. Of these patients, 56 (42.4%) had hypothyroidism and 17 (12.9%) had hyperthyroidism. The median time to hypothyroidism and hyperthyroidism was 9 months (range, 1–12 months) and 1 month (range, 1–6 months) after definitive IMRT, respectively. In patients with hypothyroidism, 41 (73.2%) had subclinical hypothyroidism and 15 (26.8%) had clinical hypothyroidism. In those with hyperthyroidism, 12 patients (70.6%) had subclinical hyperthyroidism, and five patients (29.4%) had clinical hyperthyroidism. Age, clinical stage, thyroid volume, and V45 were independent risk factors for early radiation‐induced hypothyroidism within 1 year after IMRT. Patients aged <47 years, stage III/IV disease, or pre‐irradiation thyroid volume < 14 cm3 had higher risks of developing hypothyroidism.ConclusionPrimary subclinical hypothyroidism was the most common subtype of early thyroid dysfunction in NPC patients within 1 year after IMRT. Age, clinical stage, thyroid volume, and V45 were independent risk factors for early radiation‐induced hypothyroidism in NPC patients.

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Dosimetric Predictors of Hypothyroidism After Radical Intensity-modulated Radiation Therapy for Non-metastatic Nasopharyngeal Carcinoma

Cited by 40 publications

References 32 publications

Nomogram for radiation-induced hypothyroidism prediction in nasopharyngeal carcinoma after treatment

Nomogram for radiation-induced hypothyroidism prediction in nasopharyngeal carcinoma after treatment

Thyroid dose‐volume thresholds for the risk of radiation‐related hypothyroidism in nasopharyngeal carcinoma treated with intensity‐modulated radiotherapy—A single‐institution study

Risk factors of early thyroid dysfunction after definitive radiotherapy in nasopharyngeal carcinoma patients

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