MICROSCOPIC POSITIVE SURGICAL MARGINS PREDICT RECURRENCE ONLY IN NODE-NEGATIVE PAPILLARY THYROID CARCINOMA lovekkung@gmail.com

492-04

MICROSCOPIC POSITIVE SURGICAL MARGINS PREDICT RECURRENCE ONLY IN NODE-NEGATIVE PAPILLARY THYROID CARCINOMA

3

Korea (Republic of)

Oral or Poster

Microscopic positive surgical margins (mPSMs) increased the risk of recurrence in papillary thyroid carcinoma (PTC), although recurrences rates vary widely (0.5% to 13.6%) depending on additional high-risk factors such as concurrent lymph node (LN) metastasis. This study investigated the impact of mPSM according to LN metastasis status in patients with PTC.

Between 2009 and 2023, 2,584 patients who underwent thyroid surgery for PTC were enrolled. Patients were stratified into three groups based on nodal status: N0, N1a, and N1b groups. Primary outcome measure was 5-year recurrence-free survival (RFS).

The mPSMs were found in 54(3.1%) in N0, 31(4.7%) in N1a, 17(9.3%) patients in N1b groups. After a mean follow-up of 7.7 years, 59(2.3%) patients experienced disease recurrence: 21(1.2%) in N0, 24(3.6%) in N1a, and 14(7.7%) in N1b. In the N0 group, patients with mPSM had significantly worse 5-year RFS compared to those with clear margin (88.9% vs. 99.1%; p<0.001). In contrast, no significant differences in 5-year RFS were observed between mPSM and clear margin groups in N1a (96.0% vs. 96.3%, p=0.808) or N1b (92.9% vs. 92.1%, p=0.362). mPSM was associated with a higher recurrence rates in the N0 group (HR 5.7, 95%CI 1.5-21.7), but not in N1a (HR 1.4, 95%CI 0.2-10.4) or N1b (HR 1.5, 95%CI 0.3-8.7).

Our findings demonstrate that the prognostic impact of mPSM in PTC is context-dependent, being significant only in node-negative disease. This highlights the need for tailored risk assessment and follow-up strategies based on both margin and nodal status.