The Incidence and Risk Factors of Radiotherapy Induced Hypothyroidism in Head and Neck Cancer With Long Term Follow up

Study Overview
=================
Brief Summary
-----------------
This is a retrospective study with long term follow up to evaluate the incidence, timing and risk factors of radiotherapy induced hypothyroidism in non-thyroid head and neck cancer patients who were treated with RT alone or in combination with surgery and/or chemotherapy.

Detailed Description
-----------------
For any patient, fixation was done by a thermoplastic mask. CT scan was done at 3mm thickness for the head and neck region. CT images were transferred to the planning system. Three-dimensional conformal RT, intensity-modulated radiotherapy (IMRT) or Volumetric modulated arc therapy (VMAT) was created. All patients were irradiated with once-daily fractionation at 1.8-2.0 Gy/d with 6-MV photon beams for five days a week. The gross target volume (GTV) was treated with a dose of 70Gy and the lymphatic site (CTV) and areas of high risk microscopic disease (CTV) including lymph nose levels received a radiation dose ranging from 54-66 Gy according to its risk. PTV is a circumferential margin of 5mm around CTV. Thyroid function parameters: The patient's serum T4, T3 and TSH levels, were measured during follow up. Clinical hypothyroidism is defined as the increase in TSH above 5.0mIu/ml with a decrease in free thyroxine levels (free T4) in the serum while elevated TSH with normal free T4 levels was labeled as subclinical hypothyroidism .As per institutional values, the normal values intervals of T4 level (7- 25 PMOL/L), T3( 1.5-7 PMOL/L),TSH (0.2-5 mIu/L). The median time to onset of hypothyroidism was defined as the time interval between completion of radiotherapy and first abnormal recorded T3/T4/TSH value. For all treated patients, thyroid gland was delineated and by reviewing the DVH, the V45, V50, V55, V60, V65 and V70 which means the volume of the thyroid gland receiving 45 Gy, 50 Gy, 55Gy, 60 Gy and 70 Gy respectively.

Official Title
-----------------
The Incidence and Risk Factors of Radiotherapy Induced Hypothyroidism in Head and Neck Cancer

Conditions
-----------------
Head and Neck Cancer

Intervention / Treatment
-----------------
* Diagnostic Test: TSH, T3, T4 and thyroid gland DVH


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Non-thyroid head and neck cancer patients who were treated with RT alone or in combination with surgery and/or chemotherapy Exclusion Criteria: Patients with thyroid gland disease or abnormal thyroid hormone levels before radiotherapy

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: TSH, T3, T4 and thyroid gland DVH|measuring thyroid functions and DVH parameters of thyroid gland|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The the incidence of hypothyroidism | Measuring the thyroid function tests | 8 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The risk factors of hypothyroidism | Defining the risk factors of hypothyroidism | 8 months | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
hypothyroidism, radiotherapy, head and neck cancer