Investigation of presentation characteristics and risk factors of papillary thyroid microcarcinoma for the rational selection of personalized treatment options

Objectives: Papillary thyroid microcarcinoma (PTMC) incidence has getting increased during the last two decades with increasing diagnostic test performance of high-resolution ultrasonography (USG) and fine needle aspiration biopsy (FNAB). The treatment of PTMC is controversial [1-3]. American Thyroid Association (ATA) Guidelines 2015 recommends (35C) lobectomy for PTMC patients [4]. In our institute bilateral near-total thyroidectomy (BTT) is preferred surgical procedure if the diagnosis was made before surgery. In this study, we investigated presentation characteristics and risk factors from postoperative pathology reports which provide clues for the selection of further personalized treatment and follow-up options. Methods: We retrospectively analyzed 363 consecutive thyroid papillary carcinoma (TPC) patients from our thyroid carcinoma database with at least 2 years follow up. All patients underwent bilateral total thyroidectomy and central or lateral lymph node dissections was performed some of them. Their all post-operative pathology specimens were analyzed for multifocality, bilateral involvement, capsular invasion, and lymph node metastases. In addition to their pathological findings, if they received radioactive iodine (RAI) treatment, post-therapy whole body scan findings were analyzed. Results: Post-operative pathology findings: There were 123 PTMC patients (34% of the PTC patients), the tumor was multifocal in 61 patients (49%), bilateral in 44 patients (36%). Cervical lymph node metastases (CLNMs) were detected in 34 patients (27%) patients, capsular invasion in 12 patients (9%) and extracapsular invasion in 3 patients (2%). Eighty-six patients (69%) received RAI treatment. Nineteen patients with CLNMs and Tg values 5-10 ng/mL received 3.7 GBq, 15 patients with CLNMs and Tg values more than 10 ng/mL received 5.5 GBq 131I as an adjuvant therapy dose. Seventeen patients without CLNMs and Tg values 2-5 ng/mL received 1.1 GBq and 13 patients without CLNMs and Tg values 5-10ng/mL received 1.85 GBq 131I as an ablative dose. Post-treatment whole body scan revealed additional lymph node metastases in 8 patients (7%) and distant metastases in 1 patient (0.8%) and additional therapy was planned for these patients. Twenty-two patients (17%) with a unifocal or multifocal disease without lymph node metastases and post-operative stimulated thyroglobulin (Tg) levels were less than 0.2 ng/ml didn't receive RAI treatment. All patients followed up every 6 months