Treatment for acute lymphoblastic leukemia in children is associated with papillary carcinoma of thyroid, but not with thyroid disfunction.

AIM: The treatment of acute lymphoblastic leukemia (ALL) in children may cause sequelae, some appearing only at long-term follow-up. We investigated the thyroid gland morphology and the function of the pituitary-thyroid axis in a group of patients treated for ALL in childhood.

METHODS: A cohort study was conducted at a tertiary medical center. Thirty-three children (22 males and 11 females; age: 11.9+/-3 years; range: 6 to 18 years) were studied. The mean age at the time of chemotherapy and prophylactic cranial irradiation (12-24 Gy) was 5.5+/-2.6 years (range: 1 to 14 years). The average length of the follow-up was 6.1+/-3 years (range: 2 to 12 years). Thyroid morphology (n=33) was evaluated by palpation and ultrasonography. Thyroid function (n=30) was evaluated measuring total T3 and T4, and by the thyrotrophin-releasing hormone (TRH) test. Prolactin secretion was assessed before and after injection of TRH to evaluate the diagnostic test accuracy.

RESULTS: One out of the 33 children (3%) was found to have a papillary carcinoma of thyroid four years after ALL treatment. Thyroid function was normal in all the patients, however one case (3%) showed high TSH (9.2 microU/mL) and prolactin (37.5 ng/mL) basal levels, but normal responses to TRH (TSH = 17.8 microU/mL; prolactin = 82.3 ng/mL). These hormonal alteration were not confirmed at follow-up: TSH = 1.6 microU/mL and prolactin = 13.7 ng/mL.

CONCLUSIONS: In this cohort of patients, the treatment of ALL was associated with one case of thyroid carcinoma, but it did not produce adverse effect on the thyroid function, at least after a follow-up lasted on average 6 years.