Low-Activity Radioactive Iodine Therapy for Thyroid Carcinomas Exhibiting Nodal Metastases and Extrathyroidal Extension May Lead to Early Disease Recurrence.

Related Articles

Low-Activity Radioactive Iodine Therapy for Thyroid Carcinomas Exhibiting Nodal Metastases and Extrathyroidal Extension May Lead to Early Disease Recurrence.

Thyroid. 2018 May 10;:

Authors: Chu KP, Baker SP, Zenke JK, Morad A, Ghosh S, Morrish D, McEwan S, Williams DC, Severin D, McMullen TPW

Abstract
BACKGROUND: The application of radioactive iodine in differentiated thyroid carcinomas has become more selective in an attempt to decrease morbidity. While ablative success has been documented, it is less clear how changes in radioactive iodine treatment strategies will influence long-term recurrence rates for patients with larger tumours and adverse pathological features including extrathyroidal extension and nodal metastases.
METHODS: Patients diagnosed between 1995-2008 with differentiated thyroid carcinoma treated with thyroidectomy followed by radioactive iodine treatment were eligible. All patients were followed for a minimum of 5 years using a standardized follow-up protocol requiring both biochemical and imaging assessments for recurrent disease (n=219). Patients were stratified by initial radioactive iodine activity and disease free survival was calculated using the Kaplan-Meier method with significant differences defined by the log-rank test.
RESULTS: In this cohort 46% of patients had clinical metastases and 74% had primary tumours >1.5 cm. Patients that recurred were more likely to present with extrathyroidal extension (p=0.002) and lymph node metastases at diagnosis (p<0.001). Patients presenting with both extrathyroidal extension and lymph node metastases had a significantly worse time to progression if treated with <1850 MBq radioactive iodine compared to those patients treated with > 1850 MBq (25 months vs. 121 months; p=0.004). The use of lower activity radioactive iodine ablative therapy led to more early recurrences (p=0.003). Age less or greater than 45 did not impact the time to recurrence nor did the use of level 6 dissection. On multivariate analysis, lymph node metastases at diagnosis and multiple applications of radioactive iodine were linked to increased risk of recurrence. Patients with neither, or only one, adverse pathologic feature had excellent outcomes regardless of initial ablative activity with less than 10% of patients recurring over a 10-year timespan.
CONCLUSIONS: Recurrent disease in differentiated thyroid carcinoma is associated with low activity radioactive iodine use in patients with lymph node metastases and extrathyroidal extension. These recurrences typically occur within four years of initial treatment. Patients lacking both of these risk factors treated with low radioactive iodine activity (<1850 MBq) have excellent outcomes even after 10 years.

PMID: 29742993 [PubMed - as supplied by publisher]

https://ift.tt/2KeJeIO