(0645) Factors Related to Adequate Lymph Node Yield in Patients With Papillary Thyroid Cancer

Introduction: In papillary thyroid cancer, adequate lymph node yield (ALNY) has been defined as the number of lymph nodes examined per T stage to rule out occult nodal disease with 90% confidence. ALNY for stages T1b, T2, and T3 is 6, 9, and 18 lymph nodes, respectively. We used the NSQIP database to identify factors related to ALNY.

Methods: This retrospective database study utilized the NSQIP database from 2016 to 2020. Patients with papillary thyroid cancer of T stage 1b, 2, or 3 who underwent thyroidectomy and had at least one lymph node examined were included. Factors analyzed include patient demographics, comorbidities, TNM stage, operative time, surgical specialty, postoperative complications, and length of hospital stay. ALNY was assessed over 5 years. Categorical variables were evaluated using chi squared analysis and continuous variables with analysis of variance and t-tests.

Results: Of the 11,574 patients with papillary thyroid cancer from 2016 to 2020, 4,528 met inclusion criteria. Only 34% of the total cohort had ALNY. When grouped by T stage, ALNY decreased with more advanced stages (T1b: 38%, T2: 33.6%, T3: 28.6%; p < 0.001). Patients with ALNY had longer operation times (mean = 218 minutes vs 116 minutes, p < 0.001) and hospital stays (mean = 2.14 days vs 1.16 days, p < 0.001) compared to patients without ALNY. Those with ALNY were also more likely to have recurrent laryngeal nerve injury or dysfunction (10.6% vs 6.6%, p < 0.001). Postoperative hypocalcemia within 30 days occurred in 33.1% patients with ALNY compared to 7.5% of patients without ALNY (p < 0.001). The proportion of patients with ALNY increased from 30% to 36.4% from 2016 to 2020.

Conclusions: The majority of patients in this cohort did not have ALNY as defined by previous research. Consistent with previous studies, we find that ALNY is even lower with higher T stages. The current study also suggests that ALNY is associated with longer operations, longer hospitalization, and higher risk of recurrent laryngeal nerve injury and hypocalcemia. These results can inform surgeons about the benefits and potential complications of adequate lymph node dissection.