Regional lymph node metastasis plays a pivotal role in predicting recurrence for patients with differentiated thyroid cancer (DTC). Recent studies have highlighted the prognostic potential of the lymph node ratio (LNR), defined as the ratio of positive nodes to harvested nodes. This research aims to discern and compare LNR values in patients who underwent neck dissection specifically for micropapillary DTC and those with non-micropapillary DTC.

A retrospective evaluation was conducted on patients (n=365) who underwent central neck dissection due to DTC in three different tertiary center in Istanbul, between 2013 and 2022. We evaluated the total lymph nodes and metastatic lymph nodes extracted and calculated and compared LNR ratios between the micropapillary and non-micropapillary groups.

The mean age of the patients was 44±13.1years and F/M ratio 290/75. The mean dominant nodule size measured 15.5±12.1 mm. Neck dissection procedures encompassed unilateral central neck dissection in %62 (n=226) and bilateral central neck dissection in %38 (n=139). Postoperative histopathological examination disclosed non-micropapillary carcinoma in 220 patients (60%), while 145 patients (40%) exhibited papillary microcarcinoma. The mean LNR ratio was 1.4±0.2 in patients with micropapillary DTC and 1.7 ±0.2 non-micro papillary DTC (p=0.286).

This study demonstrates that when regional lymph node metastases develop in patients with micropapillary DTC, the LNR ratio can be as high as in patients with non-micropapillary DTC. These findings emphasize that, in clinical assessments for differentiated thyroid cancer, the LNR is independent of the main tumor size.