The role of intraoperative frozen section of central neck lymph nodes in the management of patients preoperatively diagnosed with low- risk differentiated cancer.

INTRODUCTION: Histological examination during surgery (FS) has a place in the surgical management of differentiated thyroid carcinoma (DTC). Extending the indication for limited surgery to 4 cm tumor size (ATA guidelines 2015) cytologically verified DTCs, increases the emphasis on accurate patient selection. In our work, we reflected on the effectiveness of FS and its relationship to optimal patient management. METHODS: In a single-center retrospective study, we evaluated the documentation of patients indicated for primary surgery for DTC from January 1, 2016 to December 31, 2020 - there was 489 patients collectively, 121 were men, median age was 50 years (1681), 73 patients (female, age 1845 years) with preoperatively identified low-risk DTC (size 1140mm) were indicated for lobectomy. RESULTS: 34 patients (46.6%) did not meet the criteria for limited surgery 15 patients were identified from FS of the lymph nodes of the central compartment (LNCK) (15 of 25 patients) - 1 patient with false negative result and 6 patients with FS of the thyroid gland (SH) (6 / 41) - 11 patients with false negative findings. Two-step OP surgery was performed on 13 patients (17.8%). FS of LNCK identified high-risk cancer and reduced the risk of two-step surgery compared to the group of patients in whom FS was not performed or was performed from thyroid gland. The difference was statistically significant (OR 1.93, p=0.026). CONCLUSION: Approximately ½ of the patients from preoperatively identified low-risk cancers in our cohort met the criteria for limited surgery. About 30% of them eventually needed a two-step operation. Perioperative examination of LNCK helps to perform radical surgery at one time.

A different prognostic value of BRAFV600E mutation positivity in various age groups of patients with papillary thyroid cancer.

The aim of the retrospective single-center study was to assess the prognostic value of BRAFV600E mutation positivity (BRAFV600E+) on disease persistence/recurrence in patients with papillary thyroid cancer (PTC). A total of 199 patients having had initial surgery with neck dissection in our hospital between 6/2009-6/2012 were included in the cohort. Excluded were patients with unifocal microcarcinoma ≤1cm. BRAFV600E mutation was tested from formalin-fixed paraffin-embedded surgicaly removed tumors. All included patients were postoperatively treated with radioiodine. The median duration of follow-up was 43 months, quartiles range 30 - 58 months. Variables included in the final model: BRAFV600E+, categorised age, sex, and high-risk status, or alternatively lymph node status. Based on differences in persistence/recurrence rates, patients were divided into three age categories (<35, 35-60, ≥60). Multiple regression analysis showed a significant interaction between BRAFV600E+ and age, modifying the effect of BRAFV600E+ on persistence/recurrence. BRAFV600E+ in low-risk patients of any age and in high-risk middle-aged patients did not confer additional hazard compared with BRAFV600E mutation negative (BRAFV600E-) low-risk and BRAFV600E- high-risk patients, respectively. However, younger (<35 years) and older (≥60 years) high-risk BRAFV600E+ patients had 17.28 and 33.49-fold increased hazard of persistence/recurrence, respectively, compared with low-risk BRAFV600E- patients. The alternative model including lymph node status yielded similar results for the prognostic significance of BRAFV600E+ in younger and older patients. In conclusion, the prognostic value of BRAFV600E+ depends on high-risk status and likely on age-associated factors. Such additional knowledge could change clinical decision-making in treatment modality.