Vascular invasion is an independent prognostic factor for distant recurrence-free survival in papillary thyroid carcinoma: a matched-case comparative study.

OBJECTIVE: It is still unclear whether the clinicopathological and outcome characteristics of vascular invasion (VI) (+) papillary thyroid carcinoma (PTC) differ from VI (-) PTC. This study aims to establish distinguishing features of patients with VI (+) and VI (-) PTC and to investigate the biological and clinical aggressiveness of the disease in these patient groups. DESIGN: A matched-case comparative study. METHODS: 412 patients (VI (+) PTC study group n=103, and VI (-) PTC control group n=309). These two patient groups were matched 1:3 for variables of age, gender, histological variants, tumour/node/metastasis (TNM) staging and approximate duration of follow-up. Clinicopathological factors and prognosis were compared across the two patient groups. RESULTS: The median age at the time of diagnosis was 42.0 years, and 68.9% were females. Across the patient groups, the incidence of tumour multifocality in patients with VI (+) PTC was slightly higher than in those with VI (-) PTC (p=0.049). In addition, when undergoing more aggressive therapy regimens patients with VI (+) PTC showed decreased distant recurrence-free survival (DRFS), but not regional recurrence-free survival (RRFS) and disease-specific survival (DSS) compared with patients who were VI (-). VI was found to be an independent predictor of DRFS, combined with tumour size >3 cm and total thyroidectomy. CONCLUSIONS: VI was an independent risk factor for DRFS, necessitating the need for appropriate postoperative treatment and careful follow-up.