Preoperative Use Of Intravenous Contrast Media Is Associated With Decreased Excellent Response Rates In Intermediate-Risk Dtc Patients Who Subsequently Receive Total Thyroidectomy And Low-Dose Rai Therapy

Purpose:To evaluate the impact of preoperative use of intravenous contrast media (ICM) on the excellent response (ER) rates in a cohort of intermediate-risk differentiated thyroid cancer (DTC) patients who received total thyroidectomy (TT) and low-dose radioactive iodine (RAI) therapy. Methods:A total of 683 consecutive patients were retrospectively reviewed in a single center between August 2016 and August 2018. Patients were divided into ICM group (n= 532) and non-ICM group (n= 151). Intravenous contrast media patients were 1:1 propensity matched to non-ICM patients based on T stage, N stage, and urinary iodine. Risk-adjusted logistic regression models were constructed to assess the association between the use of ICM and ER rates. Results:Intravenous contrast media patients had significantly higher T stage (P< 0.001), N stage (P< 0.001), urinary iodine (P< 0.001), and ps-Tg (P= 0.042) than non-ICM patients. Preoperative use of ICM was found to be significantly associated with decreased ER rates in both the primary cohort [odds ratio (OR) = 0.47, 95% confidence interval (CI) = 0.32-0.71;P< 0.001] and the matched cohort (OR = 0.48, 95% CI = 0.25-0.94;P= 0.031). Subgroup analysis on RAI delay time in the primary cohort revealed that ER rates in ICM patients were significantly lower than that of non-ICM patients for 1-2 months (P= 0.0245) and >2-3 months (P= 0.0221) subgroups, but not for >3-4 months, >4-5 months, and >5-6 months subgroups (allP> 0.05). A delay time of >3-4 months exhibited the highest ER rate (63.08%) within the ICM group. Conclusions:Preoperative use of ICM is associated with decreased ER rates in intermediate-risk DTC patients who subsequently receive TT and low-dose RAI therapy. For such patients, if ICM has already been received, an RAI delay time of >3-4 months would seem to be more appropriate to achieve better ER rates.