214 US PATTERS AS A PROGNOSTIC FACTOR IN THYROID PAPILLARY MICROCARCINOMA: IS Mete STILL USEFUL FOR DECISION MAKING FOR FNAC AND SURGICAL STRATEGY?

Abstract Background The 2015 ATA guidelines recommend FNAC only for nodules > 1 cm, but report studies justifying FNAC also for nodules < 1 cm but with suspicious ultrasound features. The 8th edition of the AJCC TNM eliminated capsular infiltration (CI) as a negative prognostic factor. These features leave wide margins of discretion in T1a and T1b patients. Methods According to guidelines, we treated T1a and T1b patients with ultrasound signs of suspicion for extrathyroidal extension (mETE), with a total or unilateral thyroidectomy, ipsilateral central-compartment neck dissection, and extemporaneous histological verification for possible extended surgery (completing lymphectomy and thyroidectomy). We enrolled 132 patients with the following characteristics: US positive for contact of nodule with the capsule and suspect of ETE according with TIRADS classification. Patients were divided into 3 groups according to the probability of having mETE according to the ultrasound examination. Results We calculated the correlation between the presence of mETE and N1a+, specificity and Sensitivity of US in predicting CI in the two groups. In pT1a patients 68% had CI and 55% of these were N1a+. In pT1b patients 61% had CI and 52% of these were N1a+. The sensitivity of the US was 77% and the specificity 55%. Conclusions Our results demonstrate a correlation between CI and metastasis in the central compartment in both T1a and T1b patients. Furthermore, ultrasound appears to be very sensitive and low specific in predicting CI. These data question the current trend of a decreased focus on microcarcinomas on the basis of a size cut-off alone.