No evidence of chromosome damage in children and adolescents with differentiated thyroid carcinoma after receiving 131I radiometabolic therapy, as evaluated by micronucleus assay and microarray analysis.
OBJECTIVE
As (131)I therapy, used to achieve ablation of thyroid gland remnant, can cause chromosome damage in cultured peripheral lymphocytes especially, we investigated whether administration of radioiodine may induce early genome damage in peripheral T lymphocytes of adolescents with differentiated thyroid carcinoma (DTC).


METHODS
We studied 11 patients, aged 14.8 +/- 3.1 years, who assumed (131)I (range: 1.11-4.44 GBq) to ablate thyroid remnant. A blood sample for micronucleus assay and for evaluating expression of some genes involved in the DNA repair or the apoptosis pathways was obtained from each patient 1 h before (T(0)) and 24 (T(1)) and 48 h (T(2)) post-radioiodine administration.


RESULTS
Compared to T(0), we did not find any difference in the number of micronucleated cells at both T(1) and T(2) in any subject. Nine out of 11 patients had altered expression levels in a majority of the DNA repair and apoptosis genes at T(1), which decreased at T(2).


CONCLUSIONS
We demonstrated for the first time that peripheral cells of DTC children and adolescents who received (131)I at a mean dosage of 3.50 +/- 0.37 GBq did not show chromosome damage within 48 h from the end of radiometabolic therapy. This may be due to a prompt activation of the cell machinery that maintains the integrity of the genome to prevent harmful double-strand breaks from progressing to chromosome mutations, either by repairing the lesions or by eliminating the most seriously damaged cells via apoptosis.
Federico
Giovanni
G
Department of Pediatrics, Unit of Pediatric Endocrinology and Diabetes, Azienda Ospedaliero-Universitaria Pisana, Ospedali Riuniti S. Chiara, Via Roma 67, 56126, Pisa, Italy. g.federico@med.unipi.it
Boni
Giuseppe
G
Fabiani
Barbara
B
Fiore
Lisa
L
Lazzeri
Patrizia
P
Massart
Francesco
F
Traino
Claudio
C
Verola
Carmela
C
Saggese
Giuseppe
G
Mariani
Giuliano
G
Scarpato
Roberto
R
D000293:Adolescent; D017209:Apoptosis; D002467:Cell Nucleus; D002648:Child; D002875:Chromosomes / Q000235:genetics* / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D005260:Female; D020869:Gene Expression Profiling; D016678:Genome; D006207:Half-Life; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use; D008297:Male; D015162:Micronucleus Tests; D020411:Oligonucleotide Array Sequence Analysis; D013601:T-Lymphocytes / Q000473:pathology; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy
D007457:Iodine Radioisotopes