Optimal detection of hypothyroidism in early stage laryngeal cancer treated with radiotherapy

Abstract

BackgroundHypothyroidism following radiation therapy (RT) for treatment of Head and Neck Cancer (HNC) is a common occurrence. Rates of hypothyroidism following RT for Early Stage Laryngeal Squamous Cell Carcinoma (ES-LSCC) are among the highest. Although routine screening for hypothyroidism is recommended; its optimal schedule has not yet been established. We aim to determine the prevalence and optimal timing of testing for hypothyroidism in ES-LSCC treated with RT.MethodWe conducted a population-based cohort study. Data was extracted from a prospective provincial head and neck cancer database. Demographic, survival data, and pre- and post-treatment thyroid stimulating hormone (TSH) levels were obtained for patients diagnosed with ES-LSCC from 2008–2012. Inclusion criteria consisted of patients diagnosed clinically with ES-LSCC (T1 or 2, N0, M0) treated with curative intent. Patients were excluded if there was a history of hypothyroidism before the treatment or any previous history of head and neck cancers.ResultsNinety-five patients were included in this study. Mean age was 66.1 years (range: 44.0–88.0 years) and 82.3 % of patients were male. Glottis was the most common subsite at 77.9 % and the average follow-up was 40 months (Range: 12–56 months). Five-year overall survival generated using the Kaplan-Meier method was 79 %. Incidence of hypothyroidism after RT was found to be 46.9 %. The greatest frequency of developing hypothyroidism was at 12 months.ConclusionsWe found a high prevalence of hypothyroidism for ES-LSCC treated with RT, with the highest rate at 12 months. Consequently, we recommend possible routine screening for hypothyroidism using TSH level starting at 12 months. To our knowledge, this is the first study to suggest the optimal timing for the detection of hypothyroidism.

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

“…Thus, a significant proportion of patients receiving IMRT develops thyroid dysfunction, with HT being the most common complication. We observed a high rate of HT (44% of patients) after a 2-year-follow-up period, which is consistent with previous reports 4, 5, 14…”

“…The thyroid gland, as an OAR, is frequently involved in the treatment field due to its midline neck position, and the dose it receives often exceeds 50 Gy 2. Thus, one of the potential consequences of neck irradiation is development of various thyroid disorders, mainly hypothyroidism (HT), which occurs in up to 50% of patients treated with radiotherapy for HNSCC 3, 4, 5. HT is a subacute or chronic side effect of radiotherapy, with the time to development usually between 6 and 24 months after treatment.…”

Vocal-cord Only vs. Complete Laryngeal radiation (VOCAL): a randomized multicentric Bayesian phase II trial

“…Doses to the carotids between 35 and 50 Gy have been associated with carotid vessels wall thickening [ 43 ]. In addition, rates of radiation-induced hypothyroidism vary between 13 and 47% [ 35 , 44 ], with highest frequency at 1 year after treatment. Other severe toxicities of larynx RT include less than 1% risk of permanent tracheostomy due persistent laryngeal oedema and loss of functional larynx [ 35 , 45 ] and less than 1% risk of persistent mild or moderate dysphagia [ 46 ].…”

Radiation-Induced Hypothyroidism in Patients with Oropharyngeal Cancer Treated with IMRT: Independent and External Validation of Five Normal Tissue Complication Probability Models

“…The median interval between RT and hypothyroidism is approximately 1.5 years, however later toxicities are also observed [ 1 ]. In a long follow-up (>10 years), more than 50% of patients experience RIHT [ 2 , 3 , 4 ].…”