The impact of the number of harvested central lymph nodes on the lymph node ratio.

OBJECTIVE

The purpose of this study was to analyze the impact of lymph node harvest on the lymph node ratio (LNR).

METHODS

We retrospectively reviewed 106 patients diagnosed preoperatively with PTMC (papillary thyroid microcarcinoma), no evidence of central or lateral neck nodal metastasis, and who underwent a total thyroidectomy and bilateral central lymph node neck dissection (CND).

RESULTS

The median number of retrieved lymph nodes in the central compartments was 7±6.59 (range: 1-42). The mean number of metastatic lymph nodes in the central compartments on pathology was 1.1±1.79 (range: 0-7). The high node volume group (>7) had a significantly higher rate of central lymph node (CLN) metastasis than the low node volume group (≤7) in the final pathologic report (p<0.001). With the linear regression method, the number of CLN metastasis increased as the number of retrieved lymph nodes increased (correlation coefficient=0.286, p=0.003). The multivariate analysis confirmed the number of retrieved lymph nodes in the central compartments was a risk factor for high LNR (p=0.008, odds ratio 3.737). The rates of vocal fold palsy and hypoparathyroidism did not differ according to the number of retrieved lymph nodes.

CONCLUSION

The lymph node ratio in the final pathologic report is larger when a greater number of lymph nodes are retrieved during the central compartment neck dissection.