Abstract
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 (all P > 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.
Highlights
Post-operative use of radioactive iodine (RAI) continues to be conservative in differentiated thyroid cancer (DTC) patients with low to intermediate recurrence risk
Because Iodinated contrast media (ICM) contains several 100fold the recommended daily allowance of iodine and may cause a retention of iodine in the body for years [5, 6], there has long been a concern among nuclear medicine physicians that it could interfere with thyroid RAI uptake
We evaluated whether the excellent response (ER) rates were influenced by preoperative use of ICM in the setting of a lowdose RAI protocol
Summary
Post-operative use of radioactive iodine (RAI) continues to be conservative in differentiated thyroid cancer (DTC) patients with low to intermediate recurrence risk. While high dose is considered to be associated with dysfunctions in nonthyroidal organs such as salivary and lachrymal and long-term effects such as second primary cancer, plenty of studies have demonstrated that low dose is as effective as high dose in achieving ablation success and controlling disease recurrence in this patient population [1,2,3]. Iodinated contrast media (ICM) is often used in DTC patients with locally aggressive disease or clinically apparent cervical lymph node to optimize preoperative planning and the completeness of surgery [4]. When a low-dose RAI protocol is applied, the interference of preoperative use of ICM may become significantly pronounced. It is possible that the patients’ clinical outcome and management strategy will be altered in this scenario
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