Study Finds More Nodes Should Be Examined to Rule Out Node-Negative Disease in Papillary Thyroid Cancer
The proportion of patients with papillary thyroid cancer identified as having node-negative disease decreased substantially with an increased number of lymph nodes examined, according to an analysis of data from the National Cancer Database. Robinson and colleagues, of Duke University, reported these findings in the Journal of Clinical Oncology.
The study involved assessment of data from 1998 to 2012, including 78,724 patients with localized ≥ 1-cm papillary thyroid cancer who had undergone thyroidectomy with ≥ 1 lymph node examined. Of them, 38,653 were diagnosed with node-positive disease.
Effect of Number of Nodes Examined
The probability of false identification of a patient as having node-negative disease was estimated at 53% for patients with a single node examined and decreased to < 10% with examination of > 6 nodes. Among all patients, ruling out occult nodal disease with 90% confidence required examination of 6, 9, and 18 nodes for patients with T1b, T2, and T3 disease, respectively. A sensitivity analysis including only patients likely to undergo prophylactic central neck dissection showed that ruling out occult nodal disease required examination of three, four, and eight nodes in T1b, T2, and T3 disease, respectively.
The investigators concluded: “To our knowledge, our study provides the first empirically based estimates of occult nodal disease risk in patients after surgery for papillary thyroid cancer as a function of primary tumor stage and number of [lymph nodes] examined. Our estimates provide an objective guideline for evaluating adequacy of [lymph node] yield for surgeons and pathologists in the treatment of papillary thyroid cancer, and especially intermediate-risk disease, for which use of adjuvant radioactive iodine and surveillance intensity are not currently standardized.”
The study was supported by departmental funds and a P30 Cancer Center support grant.
Terry Hyslop, PhD, of Duke University, is the corresponding author of the Journal of Clinical Oncology article.
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