Comparison of Secondary and Primary Thyroid Cancers: Patient Characteristics and Postoperative Outcomes A Cross-Sectional Analysis of Patients with Primary and Secondary Thyroid Cancers

Background. Secondary thyroid cancer is believed to lead to a more aggressive clinical course than primary thyroid cancer. We aim to examine the difference between primary and secondary thyroid cancer in terms of patient characteristics and perioperative outcomes at the national level. Methods. A cross-sectional study utilizing the Nationwide Inpatient Sample database for 2003-2010 was merged with County Health Rankings Data. International Classification of Diseases, Ninth Revision (ICD-9) codes were used to identify adult patients with thyroid cancer. Results. A total of 21,581 discharge records were included. Overall, 16,625 (77.0 %) patients had primary cancer, while the rest (23.0 %) had secondary cancer. Younger (<45 years) and older ([65 years) patients, males, and those of White or Hispanic background were more likely to have secondary cancers (p < 0.05 each). The prevalence of secondary cancer was higher in communities of low health risk (24.0 % vs. 21.1 %; p < 0.024). Secondary cancer was more likely to be managed by total thyroidectomy (odds ratio [OR] 2.40, 95 % CI 2.12-2.73) and to require additional radical neck dissection (OR 12.51, 95 % CI 10.9814.25). Patients with secondary thyroid cancers were at higher risk of postoperative complications (p < 0.01 each). The cost of secondary cancer management was significantly higher than primary cancer (US$12,449.00 +/- 302.07 vs. US$7848.12 +/- 149.05; p < 0.001). However, compared with intermediate-volume surgeons, the complication risk was lower for high-volume (OR 0.47, 95 % CI 0.24-0.92; p = 0.026). Conclusions. Secondary thyroid cancer is associated with a higher risk of perioperative complications and higher cost and distinct demographic profile. Patients managed by higher-volume surgeons were less likely to experience disadvantageous outcomes.