The relationship between initial ¹³¹I uptake by lung metastases from differentiated thyroid cancer and treatment outcomes

Objective: To investigate the potential relationship between initial ¹³¹I uptake by lung metastases from differentiated thyroid cancer (DTC) and treatment outcomes. Methods: From 1997 to 2009, 41 patients with DTC lung metastases were treated in the authors' department. ¹³¹I whole body scan (WBS), serum Tg levels and other imaging results were analyzed to evaluate the therapeutic effects. Complete response (CR) or partial response (PR) was considered to be effective. The χ² test and correlation analysis were performed using SPSS 11.5 software package. Results ¹³¹I treatment was effective in 63% (26/41) patients with DTC lung metastases, CR in 8 patients and PR in 18 patients. In other 37% (15/41) patients, ¹³¹I treatment was ineffective, including one case died of distant metastases. Patients with initial presence of ¹³¹I lung uptake had higher effective rate than those with ¹³¹I lung uptake during the second or later ¹³¹I treatment (76% (22/29) vs 33% (4/12), χ²=4.911, P=0.027). Also, significantly higher effective rate was found in patients with lung metastases alone than those with extra-pulmonary metastases (75% (24/32) vs 22% (2/9), χ²=6.312, P=0.012). However, the effective rate in patients with diffuse metastases was not significantly different from that in patients with focal metastases (67% (12/18)vs 61% (14/23), χ²=0.146, P=0.702). The positive rate of initial ¹³¹I uptake by lung metastases was higher in patients with total thyroidectomy than those with partial thyroidectomy (83% (24/29) vs 42% (5/12)). Those positive rates in patients with papillary DTC and patients with follicular DTC were 72% (23/32) and 6/9, respectively. The surgical mode was correlated with the initial ¹³¹I uptake by lung metastases (r= 0.411, P<0.05), but no correlation was found between the histological type and the initial ¹³¹I uptake by lung metastases (r=0.047, P>0.05). Conclusion: Initial uptake of ¹³¹I by lung metastases alone is a favorable prognostic factor for DTC patients treated by¹³¹I, and total thyroidectomy may be beneficial for initial ¹³¹I uptake by lung metastases. (authors)