Dose-volume derived nomogram as a reliable predictor of radiotherapy-induced hypothyroidism in head and neck cancer patients

Abstract

BackgroundThe aim of this study was to determine the possible predictive value of various dosimetric parameters on the development of hypothyroidism (HT) in patients with head and neck squamous cell carcinoma (HNSCC) treated with (chemo)radiotherapy.Patients and methodsThis study included 156 patients with HNSCC who were treated with (chemo)radiotherapy in a primary or postoperative setting between August 2012 and September 2017. Dose-volume parameters as well as V10 toV70, D02 to D98, and the VS10 to VS70 were evaluated. The patients’ hormone status was regularly assessed during follow-up. A nomogram (score) was constructed, and the Kaplan-Maier curves and Log-Rank test were used to demonstrate the difference in incidence of HT between cut-off values of specific variables.ResultsAfter a median follow-up of 23.0 (12.0–38.5) months, 70 (44.9%) patients developed HT. In univariate analysis, VS65, Dmin, V50, and total thyroid volume (TTV) had the highest accuracy in predicting HT. In a multivariate model, HT was associated with lower TTV (OR 0.31, 95% CI 0.11–0.87, P = 0.026) and Dmin (OR 9.83, 95% CI 1.89–108.08, P = 0.042). Hypothyroidism risk score (HRS) was constructed as a regression equation and comprised TTV and Dmin. HRS had an AUC of 0.709 (95% CI 0.627–0.791). HT occurred in 13 (20.0%) patients with a score < 7.1 and in 57 (62.6%) patients with a score > 7.1.ConclusionsThe dose volume parameters VS65, Dmin, V50, and TTV had the highest accuracy in predicting HT. The HRS may be a useful tool in detecting patients with high risk for radiation-induced hypothyroidism.

Research progress of radiation-induced hypothyroidism in head and neck cancer

“…Prpic et al 40 analyzed retrospectively 156 patients with head and neck cancer treated with IMRT and showed that thyroid dose parameters VS65, minimum dose (Dmin), and V50 were related to the incidence of hypothyroidism. Sachdev et al 41 suggested that thyroid V50 < 60% should be set as the optimal dose parameter.…”

Thyroid V50 is a risk factor for hypothyroidism in patients with nasopharyngeal carcinoma treated with intensity-modulated radiation therapy: a retrospective study

“…This difference may be related to the follow-up time, sample size, and treatment planning systems. Thyroid V 50 is an important prognostic variable for radiation-induced HT in patients with NPC [23]. For example, Ling et al [24] retrospectively analyzed 102 patients and recommended thyroid V 50 < 50% as the optimal dose-volume limiting threshold for HT after radiotherapy.…”

Dose-volumetric Predictors for Thyroid Dysfunction after 3D Conformal Radiotherapy: An Observational, Prospective Study

“…Also, the retrospective nature of some studies contributed to this variation. Using 3DCRT alone like our study and El-Sherbiney et al study [16] may contribute to different outcomes than using IMRT in other studies [2,14,15,28].…”

“…Our results have shown that the incidence of RIHT after maximum follow up of 24 months was 26%. The range of reported incidence from similar studies ranged from 17-47% [2,5,15,16,18,19]. Our follow up period is relatively short and the incidence is expected to increase with longer follow up periods.…”

“…Various authors have conducted similar studies on patients who have the same cancer type like nasopharyngeal carcinoma [13], laryngeal carcinoma [14] or oropharyngeal carcinoma [2]. Other authors have studied the same topic on cohorts with variable malignancies [3,15].…”