23. Principles of radioiodine treatment ( I) for patients with differentiated thyroid carcinomas

Abstract

The aims of radioiodine (¹³¹ I) therapy for patients with differentiated thyroid carcinomas:

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  Destruction of thyroid tissue remaining after thyroidectomy

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  Destruction of microcarcinoma focus in site of thyroid

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  Destruction of metastases in lymph nodes

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  Destruction of distant metastases

Therapeutic indications for radioiodine (¹³¹ I) treatment in differentiated thyroid carcinomas

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  Complementary treatment

This treatment is recommended in all patients with follicular or papillary carcinomas in stage pT_1b-4 N_0-1 M₀ after total thyroidectomy. In some cases it could be as the complementary treatment after incomplete thyroidectomy.

The recommended radioiodine activity for the complementary therapy is from 1.75 to 3.5 GBq (60–150 mCi)

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  Radical treatment

This kind of treatment is recommended for patients with differentiated thyroid carcinomas and remote metastases. If the lesions concentrate ¹³¹ I in quantities sufficient for radical treatment – the patient can be treated with the isotope.

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  Palliative treatment

Palliative treatment is recommended for patients with inoperable thyroid carcinoma or with local recurrence, or with remote metastases concentrating radioiodine in quantities non sufficient for radical treatment.

Contraindications for radioiodine (¹³¹ I) treatment

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  Pregnancy

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  Breast-feeding

The contraception for women is necessary during 12 months after radioiodine treatment. For men the 4 – 6 months contraception is recommended.

Method of radioiodine (¹³¹I) administration

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  Patient serum TSH concentration should be above 30 ulU/ml

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  Isotope administration is possible 4 – 6 weeks after total thyroidectomy or 4 –6 weeks after L-thyroxin treatment withdrawal

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  radioiodine therapy should be followed by body radioiodine scan performed at 72 hours after the therapeutic dose – to asses focuses concentrating radioiodine

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  After administration of therapeutic radioiodine dose the patient for 14 days should avoid to be in contact with other persons, especially with children and pregnant women

Complications after radioiodine (¹³¹ I) treatment

The complications are very rare and usually without clinical manifestations.

Follow-up after radioiodine (¹³¹I) treatment

Follow-up at intervals 6 – 12 months after radioiodine treatment should include careful physical examination, neck ultrasonography, needle biopsy examination is indicated if a lump is noted. Serum thyroglobulin and TSH concentration should be measured. Radioiodine body scan should be performed 6 months after treatment – after 4 – 6 weeks of L-thyroxin treatment withdrawal