Papillary thyroid carcinoma: the impact of histologic vascular invasion.

Background: The American Thyroid Association (ATA) recurrence risk prediction system considers vascular invasion (VI) as a relative indicator for adjuvant radioactive iodine (RAI) treatment, nevertheless VI final role in PTC management is yet to be defined. This study aims to assess the impact of histologic VI in papillary thyroid carcinoma (PTC).

Methods: A retrospective study with PTC patients admitted in our Thyroid Cancer Unit, between January 1960 and December 2016 was performed. We reviewed 905 patient records with 275 having full information about VI on their pathological reports. Demographic and clinical variables were obtained, and univariate/multivariate analysis was performed in order to obtain potential predictive prognostic factors.

Results: Fifty-one out 275 patients presented VI (18.5%; 95% CI 14.4-23.6%), these individuals had larger tumors (median 19 mm vs. 12 mm, P<0.001) with more frequent extraglandular invasion (54.0% vs. 17.1%, P<0.001), regional lymph nodes involvement (29.8% vs. 12.6%, P=0.003)and distant metastasis (10.9% vs. 1.9%, P=0.003) at diagnosis. VI was an independent predictor for regional lymph node and/or distant metastasis at diagnosis (OR 2.93 [IC 95% 1.16-7.41, P=0.008]). After a median follow-up time was 68.5 months patients with VI presented higher rates of local recurrence and lymph node metastasis recurrence.

Conclusions: In this study, the presence of VI in PTC is associated to higher rate of lymph node and distant metastasis at diagnosis. Its presence should be probably considered an adverse prognostic factor in PTC, perhaps justifying more aggressive therapeutic and follow-up approaches in such cases.