Does a Restrictive Diagnostic Work-up for Thyroid Nodules Lead to a Different Papillary Thyroid Cancer Patient Population? A Comparison Between Dutch and U.S. T1-T3 Patient Population.

Introduction: The 2015 American Thyroid Association guidelines recommend de-escalating surgical treatment for papillary thyroid cancer (PTC). We hypothesize that the Dutch PTC population might differ due to a restrictive diagnostic policy that mainly selects symptomatic and palpable thyroid nodules for further diagnostics, potentially selecting relatively more aggressive tumors. We aimed to describe the Dutch PTC population because differences in populations can have consequences for the adoption of foreign guidelines.

Methods: From the Dutch national cancer registry, patients diagnosed with pT1-T3 PTC between 2005 and 2015 were included. Baseline characteristics, disease-free interval, and overall survival were compared between low-risk and non-low risk PTC. Furthermore, the TNM stage of the Dutch and U.S. cohorts were compared via literature search.

Results: Of the 3368 pT1-T3 patients included, 1813 (53.8%) had a low-risk PTC, and 1555 (46.2%) had a non-low-risk PTC. In the Dutch PTC population, pT1 tumors occurred in 45.8%, pT2 and pT3 tumors occurred in 34.9% and 19.3% of the patients, respectively. Of all patients, 10.2% had central lymph node metastases and 16.6% had lateral lymph node metastasis. Distant metastasis only occurred in 18 (0.5%) of the patients. The 10-year overall survival was 89.6%, with rates of 91.6% for low-risk and 87.3% for non-low-risk patients (p = < 0.001). During the follow-up period, 257 patients (7.6%) had a recurrence.

Discussion: The higher frequency of advanced tumors among the Dutch PTC population in contrast to the U.S. emphasizes the need for careful national data analyses before the adoption of surgical intervention de-escalation protocols from other countries.