Adults with differentiated thyroid cancer who underwent thyroidectomy and started radioiodine therapy 3 or more months after surgery may have an incomplete treatment response compared with those initiating therapy earlier, according to researchers in China.
Yan-Song Lin, MD, PhD, of the department of nuclear medicine at Peking Union Medical College Hospital in Beijing, and colleagues evaluated data on 235 adults with low- to intermediate-risk differentiated thyroid cancer (DTC; median age at diagnosis, 42 years) to determine the effect of radioiodine (RAI) initiating time on response to initial therapy. Participants were divided into two groups based on RAI therapy initiation time: less than 3 months after thyroidectomy (n = 187) and at least 3 months after thyroidectomy (n = 48). Median follow-up was 780 days.
“RAI therapy plays an important role in the management of DTC and has been used worldwide for decades, but the relationships between RAI initiating time and clinical outcome remains unknown,” the researchers wrote.
No differences were observed between the two groups for age, sex, histopathologic type, status of tumors and nodes, dose of RAI, values of thyroid-stimulating hormone and stimulated thyroglobulin, or follow-up time.
The later initiation group compared with the earlier initiation group had a higher incomplete response rate (18.8% vs. 4.3%; P = .001) and lower excellent rate proportion (62.5% vs. 78.1%; P = .027). Significant risk factors for incomplete response were status of tumors and nodes, stimulated thyroglobulin and timing to initiation (P < .05 for all).
The risk for incomplete response was 3.77 times higher in participants who initiated RAI 3 or more months after thyroidectomy compared with those who began therapy earlier. – by Amber Cox
Disclosures: The authors report no relevant financial disclosures.