Macroscopic extranodal invasion is a risk factor for tumor recurrence in papillary thyroid cancer.

Papillary thyroid cancer patients, upon whom curative operation was performed, were investigated to clarify whether or not macroscopic extranodal invasion is a risk factor for recurrence. They were divided into three groups: group A, patients whose primary tumor showed extrathyroidal invasion (n=31); group B, those whose metastatic lymph nodes showed extranodal invasion (n=6); group C, those who showed both extrathyroidal and extranodal invasion (n=9). Recurrence was significantly higher in groups B and C than in group A (P<0.05). It was concluded that macroscopic extranodal invasion to the adjacent structures was a risk factor for recurrence in patients with papillary thyroid cancer.