Sperm DNA fragmentation after radioiodine treatment for differentiated thyroid cancer

BACKGROUND: Treatment of differentiated thyroid cancer usually consists of a total thyroidectomy followed by one or several courses of radioiodine ((131)I). (131)I is known to have deleterious effects on radiation sensitive tissues and irradiation to the testes has been shown after its administration. We investigated effects of such treatment on sperm DNA in a patient with differentiated thyroid carcinoma. METHODS: The patient, a 32-year-old male with differentiated thyroid carcinoma treated by total thyroidectomy and radioiodine therapy, performed 6 semen samples in total, 3 for sperm banking and 3 for semen exploration, that were analysed for classic semen parameters. DNA integrity was analysed by flow cytometry: sperm DNA fragmentation index (DFI) and high DNA stainability (HDS) were analyzed by sperm chromatin structure assay, DNA fragmentation was analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. RESULTS: Moderate oligozoospermia was observed as early as 3 months after a first dose of (131)I and became severe at 5 months. Total sperm count was reduced up to 12 months after the second dose of (131)I. Sperm DFI was increased 3.25 months after the first dose of (131)I. All parameters returned to normal values 28 months after the second (131)I dose. CONCLUSIONS: Treatment with (131)I induces alterations in sperm chromatin as well as in sperm parameters a short time (3 months) after a first dose of (131)I with persistence of sperm alterations until 12 months after a second dose. Sperm banking should be recommended before treatment.