Endocrine Abstracts

Introduction: Active surveillance (AS) is proposed as an option for the treatment of papillary thyroid microcarcinoma (PTMC), considering the indolent nature of papillary thyroid cancer. However, ongoing discussions are needed regarding the selection of target patients and long-term safety.

Methods: We enrolled patients who delayed surgery for more than one year after being diagnosed with PTMC from 2014 to 2021 at a single center, and they followed until 2023. Primary end-point was delayed surgery, and the secondary end-point was the progression of disease. Based on the tumor volume doubling time of PTMC, progression was grouped as rapid-growing disease if less than 3 years, slow-growing disease if it was between 3 and 10 years, and stable disease if it was more than 10 years.

Results: A total of 75 patients were analyzed. Their mean age was 50 years, and 57 patients (76%) were female. The patients were followed up for a median time of 4.5 years, of which 21 (28%) patients underwent surgery after a median time of 3.2 years. Lymph node metastasis was identified in 7 patients (33%) of the delayed surgery group. When the primary end-point was analyzed using multivariable Cox-regression, the characteristics of patients who underwent surgery during the follow-up period were those with a baseline maximal diameter of 0.7 cm (P < 001) or more or those in the rapid-growing group (P < 001). For secondary end-points with multivariable logistic regression, we found that BRAF mutation was associated with rapid-growing disease, and sonographic feature without echogenic foci were associated with stable disease.

Conclusions: PTMC in this cohort who voluntarily chose AS reported stable disease for a considerable period of time. BRAF mutational status may help to predict rapid growing disease during AS of PTMC. [This research was supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education (RS-2023-00245534).]