L. N. Pontius1, L. M. Youngwirth1, S. M. Thomas1, R. P. Scheri1, S. A. Roman1, J. A. Sosa1 1Duke University Medical Center,Durham, NC, USA
Introduction: Data regarding the association between lymphovascular invasion for survival for papillary thyroid cancer (PTC) are limited. This study sought to examine lymphovascular invasion as an independent prognostic factor for patients with PTC undergoing total thyroidectomy.
Methods: The National Cancer Data Base (2010-2011) was queried for all patients with a diagnosis of PTC undergoing total thyroidectomy. Patients were classified into two groups based on the presence/absence of lymphovascular invasion. Demographic, clinical, and pathologic features at the time of diagnosis were evaluated for all patients. A Cox proportional hazards model was developed to identify factors associated with survival.
Results: In total, 40,324 patients met inclusion criteria; 12.5% had lymphovascular invasion. Patients with lymphovascular invasion were more likely to have larger tumors (2.8 cm vs 1.6 cm, p<0.01), metastatic lymph nodes (75.1% vs 34.1%, p<0.01), and distant metastases (3.1% vs 0.5%, p<0.01). They also were more likely to receive radioactive iodine when compared to patients without lymphovascular invasion (70.2% vs 48.7%, p<0.01). Unadjusted overall survival was reduced for patients with lymphovascular invasion compared to patients without it (log-rank p<0.01), with 5-year survival rates of 86.1% and 94.2%, respectively. After adjustment, increasing patient age (HR=1.06, p<0.01), male gender (HR=1.63, p<0.01), presence of metastatic lymph nodes (HR=1.73, p<0.01), presence of distant metastases (HR=4.90, p<0.01), and presence of lymphovascular invasion (HR=1.99, p<0.01) all were associated with compromised survival. Treatment with radioactive iodine was protective in both patients with lymphovascular invasion (HR=0.42, p<0.01) and patients without lymphovascular invasion (HR=0.48, p<0.01).
Conclusion: The presence of lymphovascular invasion among patients undergoing total thyroidectomy for PTC is independently associated with compromised survival. Patients with PTC and lymphovascular invasion should be considered higher risk, and providers should consider aggressive surgical and adjuvant treatment measures to maximize patient outcomes.