Risk Estimates Identified for Occult Nodal Disease in Thyroid Cancer After Surgery

Researchers have identified estimates for risk of occult nodal disease of patients with papillary thyroid cancer who have undergone surgery, in a study published in the Journal of Clinical Oncology.¹

Timothy Robinson, MD, and colleagues at Duke University in Durham, NC, evaluated data from 78,724 patients identified through the National Cancer Database who were diagnosed with localized ≥ 1 cm papillary thyroid cancer and had undergone thyroidectomy with 1 or more lymph nodes examined.

They estimated for the probability of occult nodal disease as a function of total number of lymph nodes examined and pathologic tumor stage through β-binomial distribution. In total, 38,653 patients had node-positive disease.

It was estimated that the probability of falsely identifying a patient as node negative was 53% for those patients with a single node examined, decreasing to less than 10% when more than 6 lymph nodes were examined.

To rule out risk of occult nodal disease with 90% confidence, they determined that 6 nodes would need to be examined for patients with T1b disease, 9 nodes for those with T2 disease, and 18 nodes for those with T3 disease.

Upon undergoing sensitivity analyses for those patients who were found to likely undergo prophylactic central neck dissection, they found that 3, 4 and 8 nodes would be needed to provide comparable adequacy of lymph node evaluation.

Reference

1. Robinson TJ, Thomas S, Dinan MA, et al. How many lymph nodes are enough? Assessing the adequacy of lymph node yield for papillary thyroid cancer. J Clin Oncol. 2016 Aug 15. doi: 10.1200/JCO.2016.67.6437 [Epub ahead of print]