Clinical significance of extrathyroidal extension to major vessels in papillary thyroid carcinoma

Purpose: Gross extrathyroidal extension (gETE) into major vessel is considered the most advanced stage of the locally advanced papillary thyroid cancer (PTC). Surgical intervention may not benefit some patients at this disease stage or even result in intraoperative death due to massive hemorrhage; however, it is still considered an effective strategy for most cases. The lack of description for this challenging invasion in PTC warrants detailed characterization of its pattern, risk factors, optimal surgical method, and prognostic value.

Methods: In total, 3127 patients diagnosed as having PTC were enrolled and categorized into two the following groups, namely the major vessel invasion (MVI) group (n = 30) and the control group (n = 3097). Data regarding clinicopathological and demographic characteristics, vascular invasion sites, postoperative complications, locoregional recurrence, distant metastasis, and surgical strategies were collected. Predictive disease-free survival (DFS) was also compared between the two groups.

Results: MVI was independently associated with invasion of the esophageal extension, age < 55 years, tumor size > 1 cm, lateral lymph node metastasis, and distant metastasis (P = 0.00; P = 0.01; 0.05; P = 0.00; P = 0.00, respectively). The difference in the predictive DFS between the two groups was significant (P = 0.00), and the difference remained significant even in patients with ETE when compared with patients without ETE (P = 0.00). Additionally, predictive DFS did not differ significantly between patients who received vessel repairment and those who received vessel resection (P = 0.28).

Conclusions: This study first characterized the gross MVI pattern exhibited by PTC and the risk factors for MVI. Additionally, it demonstrated the DFS of patients with PTC. Extensive gross MVI significantly worsened the biological characteristics of PTC. Regardless of the high risk and difficulty of the operation, patients still benefited from the surgical intervention, and vessel repairment may be the optimal surgical strategy.