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Higher dose radioactive iodine improved response to therapy in older PTC patients
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Radioactive iodine as an adjuvant therapy for patients with papillary thyroid cancer and lateral neck lymph node metastases helped some patients when given in larger doses, according to research published in Thyroid.
The smallest dose was unlikely to improve the initial response to therapy, particularly for younger patients still in stage I, but larger doses could reduce structural persistent response in older patients in Stage IVa with a high risk for poor outcomes.
Mona M. Sabra, MD, along with colleagues at the Memorial Sloan-Kettering Cancer Center and Weill-Cornell College of Medicine in New York, conducted a retrospective review of data for 181 patients with papillary thyroid cancer with N1b disease. They had undergone total thyroidectomy, neck dissection and radioactive iodine (RAI) remnant ablation.
Mona M. Sabra
The investigators determined dose–response relationships between administered activity of iodine — low administered activity (100 mCi), intermediate administered activity (150 mCi) and high administered activity (>200 mCi) — and best response to initial therapy.
No clinical evidence of disease status (NED) was achieved by 39% of patients following the initial therapy. Younger patients showed a trend toward higher rates of NED with increasing dose (34% low activity; 36% intermediate activity; 46% high activity) that was not statistically significant; doses did not appear to affect structural persistent response to initial therapy or biochemical evidence of disease.
“Administering more than 100 mCi of RAI as adjuvant therapy in N1b disease is unlikely to improve the initial response to therapy in younger patients with papillary thyroid cancer presenting with lateral node involvement,” the researchers wrote.
The trend in dose–response relationships for older patients was statistically significant, with increasing administered activities associated with reduced rates of structural persistent response (46% low activity; 23% intermediate activity; 17% high activity). The lower rate of structural persistent slightly increased the likelihood for NED; it was associated with more biochemical persistent disease classification at 12 to 18 months.
“The potential benefit from higher RAI activities should be balanced against potential adverse effects in that subgroup of patients,” the researchers wrote.
Disclosure: The researchers reported no relevant financial disclosures.
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