Association of the Cumulative Dose of Radioactive Iodine Therapy With Overall Survival in Patients With Differentiated Thyroid Cancer and Pulmonary Metastases

Abstract

Purpose: The optimal cumulative dose of radioactive iodine therapy (RAIT) for patients with differentiated thyroid cancer (DTC) and pulmonary metastases (PM) is not known, therefore we evaluated the association between the cumulative dose of RAIT and overall survival (OS). Methods: A total of 202 patients with DTC and PM who underwent thyroidectomy and RAIT were analyzed in this study. The median cumulative dose of RAIT was 530 mCi. OS was compared with an age- and sex-matched general population from China to assess relative survival. Multivariable proportional hazards model smoothing by penalized spline was applied to identify independent predictors and examine the adjusted non-linear association of cumulative dose of RAIT and patient age with mortality. Results: The observed survival and relative survival at 10 years was 54.96 and 60.81%, respectively, with the standardized mortality ratio being 5.34. The cumulative dose of RAIT was associated with mortality in a dose-dependent fashion without an apparent cutoff point after adjustment of other variables. A linear but moderate association was found in the dose of 300 to 1,000 mCi. Cumulative dose of RAIT, patient age, diameter of pulmonary metastases, and extrapulmonary metastases were identified as independent predictors for OS. The increasing patient age was associated with mortality in a non-linear pattern, with the optimal threshold being 40 years. With advancing age, the risk of death increases rapidly in patients aged 40 years and younger, but slowly in patients over 40 years. Conclusions: RAIT should be assigned to RAI-avid patients until disease has been controlled or RAIT becomes refractory after consideration of the potential long-term side-effects. Patient age was associated with OS in a non-linear pattern, with a threshold at 40 years. Consideration of age as a binary variable could elucidate a more accurate prognosis in such patients.

Evaluation of recurrence risk in patients with papillary thyroid cancer through tumor-node-metastasis staging: A single-center observational study in Taiwan

“…Patients who given relatively high doses of I-131 are often in more serious disease status. Therefore, although higher accumulated doses of radioactive iodine can reduce patient's overall survival [ 38 ], due to its slow ablation effect, it might have a limited effect on the reduction of recurrence rate of some more aggressive cancer subtypes such as tall cell type or insula type. We were unable to further confirm the above inference due to incomplete clinicopathological data.…”

The association between the interval of radioiodine treatment and treatment response, and side effects in patients with lung metastases from differentiated thyroid cancer

“…Previous patient-based studies have demonstrated several variables associated with the efficacy of cumulative RAI treatment in patients with lung metastases from DTC ( 12 , 15 , 16 ). However, they hardly provide more reliable evidence for or against extending the interval between the neighboring RAI treatment, as well as predicting response to the next RAI treatment.…”

The Increased Risk of Thyroid Cancer-Specific Mortality With Tumor Size in Stage IVB Patients

“…Differentiated thyroid cancers (DTC), which consist of papillary thyroid cancer (PTC), and follicular thyroid cancer (FTC), account for ~>90% of TC ( 6 , 7 ). However, patients with initial distant metastasis still suffer a high risk of mortality ( 8 – 10 ). About 10–15% of patients with TC are at an advanced stage ( 11 ).…”