Clinical Outcome and Quality of Life in Differentiated Thyroid Cancer Patients Treated With Different Doses of Radioactive Iodine.

Differentiated thyroid cancer represents more than 90% of cancer thyroid [1]. Total thyroidectomy is considered the mainstay of curative therapy, with radioactive iodine (RAI) in order to ablate or treat remnant thyroid tissue in the surgical bed and/or elsewhere [2]. The two main objectives for treatment of differentiated cancer thyroid are reducing the probability of cancer recurrence and facilitating serological surveillance via thyroglobulin (TG). The 2015 American Thyroid Association (ATA) guidelines as well as European Consensus Conference described three main risk stratification for thyroid cancer including: low, intermediate and high risk [3] [4]. According to the 2015 ATA guidelines, low- dose (1110 MBq) 131I ablation is recommended for low-to- intermediate-risk patients, while high-dose (3700 MBq or more) 131I ablation may be required for high-risk patients to remove microscopic residual disease(4). The optimal RAI activity needed to achieve the best objective RAI response and to minimize RAI specific adverse effects is not known since there are many factors that should be considered while determining the dose including age of the patient and many pathological factors [5, 6]. Therefore, dose adjustment might be needed for patients with same risk classification. Just following the guidelines might not be optimal for treatment of individual differentiated thyroid cancer [5]. Accordingly, in our centre the administrated activities are varied among our clinicians. In this study, we aim to retrospective analyse patients with differentiated thyroid cancer received variable (single and multiple) doses of RAI in each risk group and to assess their clinical outcome. As thyroid cancer has a very good prognosis, there a debate that quality of life may be affected in patients with high risk compared to low and intermediate risks. Additionally, we intend to evaluate the impact of thyroid cancer on quality of life by questionnaire filled by patients with different risk groups.