Abstract
To evaluate treatment outcomes following radioactive iodine (RAI) treatment with a
cumulative dose of ≥≥600 mCi in differentiated thyroid carcinoma (DTC) patients, a
retrospective review of medical records was done in 176 DTC patients with a cumulative
dose of ≥600 mCi from January 1993 to December 2013. All patients were followed up
for at least 2 years after receiving 600 mCi of I-131 treatment. Remission criteria
were no clinical and imaging evidence of disease and low serum thyroglobulin levels
during thyroid-stimulating hormone suppression of <0.2 ng/ml or of <1 ng/ml after
stimulation in the absence of interfering antibodies. A total of 176 patients were
included in the study: 137 – papillary thyroid cancer, 29 – follicular thyroid cancer,
9 – mixed papillary and follicular thyroid cancer, and 1 – Hurthle cell carcinoma.
Most of the patients (118, 67%) had locoregional metastasis, whereas 48 patients (27%)
had distant metastases at presentation. The median cumulative dose was 900 mCi (range:
600–2200 mCi). The mean follow-up period was 82.84 ± 42.41 months. Only 16 patients
(9.1%) met remission criteria at the end of treatment. The rest of patients (160,
90.9%) were not remitted: stable disease in 94 (53.4%), at least 1 metastasis without
I-131 uptake in 34 (19.3%), progressive disease in 21 (11.9%), and death during the
whole follow-up period in 11 (6.3%). Two patients (1.1%) developed second primary
malignancy. Eighteen cases were suspected of bone marrow suppression (14 cases [7.9%]
had anemia and 5 cases [2.8%] had neutropenia). Seven patients (3.9%) developed permanent
salivary gland dysfunction. Although the complications after receiving RAI treatment
with a cumulative dose of ≥≥600 mCi were low and not severe, the patients with remission
were in <10%. Our study suggests that the decision to administer further treatments
should be made on an individual basis because beneficial effects may be controversial.
Keywords
600 mCi - cumulative dose - differentiated thyroid cancer - radioiodine therapy
