Hypothyroidism is common following radiotherapy in patients with head & neck tumors. The association between radiotherapy and hypothyroidism in breast cancer patients has been investigated in only few studies. On the other hand, radiation exposure to parts of the thyroid gland seems unavoidable in breast cancer patients receiving radiotherapy to the ipsilateral supraclavicular fossa. Studies reveal that hypothyroidism is related to volume of thyroid gland and dose received. This study is taken up to find such correlation between volume of thyroid and thyroid function test.
A total of 83 patients treated with adjuvant radiation therapy in carcinoma breast were included. All patients were treated with 3DCRT. V20, V30, V40 and V50 calculated for all patients using standard DVH. Base line thyroid function test and clinical assessment was done before radiation therapy. All patients were treated with 50Gy in 25 fractions (Conventional arm) or 40Gy in 15 fractions (Hypo fractionated arm) to chest wall and SCF. After therapy, TFT and clinical evaluation were done at every 3 months interval for a year.
Mean thyroid volume was found to be 10.3cc. Mean dose received by thyroid gland was 47.5Gy in Conventional arm and 38Gy in Hypo fractionated arm. The V20, V30, V40 and V50 of thyroid gland in the Conventional arm were 60.6, 56.5, 53.3 and 35.2%. Mean TSH change between baseline and 1 year was 40.9% in Conventional arm and 35.2% in Hypo fractionated arm.Table: 60P
|n = 83||Subclinical hypothyroidism||Clinical hypothyroidism||Total|
|Baseline (0 month)||0||1||1|
|Conventional arm (n = 43)||5||3||8|
|Hypofractionated arm (n = 40)||1||3||4|
|Conventional arm (n = 43)||4||5||9|
|hypofractionated Arm (n = 40)||2||4||6|
No significant correlation was observed with radiation dose to thyroid gland and thyroid function test. A significant correlation was noted with TSH level and thyroid volume in the 50Gy arm. Thyroid volume
In our study we did not find any significant correlation between thyroid radiation doses with the changes in TFT parameter. Patients who received conventional fractionation and with thyroid volume
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All authors have declared no conflicts of interest.