Determinants of physicians' risk-benefit perceptions of adjuvant radioactive iodine for differentiated thyroid cancer.

PURPOSE: Selective use of radioactive iodine is advocated in recent guidelines. We aimed to characterize clinical practice and factors associated with its prescription in low- or intermediate-risk differentiated thyroid cancer patients among Spanish physicians. METHODS: A cross-sectional survey was conducted in 2022 among Spanish physicians. The survey assessed preferences for radioactive iodine administration in different differentiated thyroid cancer clinical scenarios with excellent response to surgery. RESULTS: Ninety-six responses were received. In low-risk differentiated thyroid cancer, radioactive iodine was most often used to facilitate follow-up (40%), or to reduce the risk of recurrence (23%). Activity of radioactive iodine was selected according to treatment intention by 96% of respondents; but more than 50% of low-risk differentiated thyroid cancer patients received radioactive iodine treatment in the clinical setting of 2/3 of the respondents; and 13% routinely recommend adjuvant activities in this setting. In intermediate-risk differentiated thyroid cancer, the main objective of radioactive iodine administration was to reduce the risk of recurrence (81-83%). Adjuvant radioactive iodine was perceived to be well or very well tolerated (96% of respondents); with a positive risk-benefit balance in patients with low-risk (50%) or intermediate-risk (90%) differentiated thyroid cancer. Factors influencing physicians' likelihood to recommend radioactive iodine included an overestimation of its benefits; and underestimation of its risks; and perceived increased risk with increasing tumor size, nodal involvement, BRAF V600E mutation, and follicular/oncocytic histology. CONCLUSIONS: This survey shows discrepancy between reported clinical practice and current consensus guidelines as well as variation in practice patterns in Spain regarding [131I]NaI treatment.