NEW YORK (Reuters Health), Sep 23 - Thyroid nodules are not rare in children after radiation for cancer, Italian researchers report in the September European Journal of Cancer. However, close surveillance and early therapy appear to limit these sequelae.
"Postradiation thyroid alterations both related to functions -- mainly iatrogenic hypothyroidism -- and to parenchymal damages -- nodules, secondary tumors," lead investigator Dr. Maura Massimino told Reuters Health, "may represent a never-ending concern for cured patients."
To investigate possible grounds for such concern, Massimino and colleagues at Fondazione IRCCS Istituto Nazionale Tumori in Milan studied two separate cohorts, one retrospective and the other prospective.
In the retrospective phase, the researchers analyzed 468 patients diagnosed with childhood cancers between 1975 and 1997 whose treatment had involved partial or total thyroid parenchyma irradiation. In this cohort, 128 patients (27%) developed nodules, and 22 of 58 biopsied patients were found to have differentiated carcinoma. Transient or persistent hypothyroidism was documented in 57% of the patients who developed nodules.
In the prospective phase, the authors followed 144 children with nonthyroid primary cancers that were diagnosed from 1998 through 2004 and treated with radiation fields involving the thyroid. All were euthyroid and nodule-free at diagnosis. Any iatrogenic hypothyroidism was promptly addressed.
Over a median of 81 months, 19 (13%) patients developed nodules, all of which were solitary and less than 1 cm in diameter.
"As soon as we started the retrospective evaluation, we also launched a prospective assessment of newly accrued patients," the researchers said. "Early evaluation disclosed a median time to discovery of nodules of 54 months -- far less than the 14 years found in the retrospective series."
In the prospective cohort, the authors point out, there were fewer nodules, and when nodules did occur they were smaller. "It seems likely" that these findings will eventually translate into "fewer cases of adenocarcinoma in the longer term," they add.
"In this report," the researchers conclude, "we have ... shown that careful surveillance of irradiated patients ... is useful in monitoring any onset of nodules. After a longer follow-up, we shall see if this is true of malignant transformation as well."
By David Douglas
Eur J Cancer 2009;45:2546-2551.
Last Updated: 2009-09-22 13:26:52 -0400 (Reuters Health)
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