Prognostic implications of microscopic involvement of surgical resection margin in patients with differentiated papillary thyroid cancer after high-dose radioactive iodine ablation.

OBJECTIVE: To evaluate the relationship between microscopic cancerous involvement of surgical margin and recurrence in patients with differentiated papillary thyroid cancer (PTC) who underwent total thyroidectomy followed by high-dose radioactive iodine ablation (HDRIA).
METHODS: Consecutive 197 PTC patients (184 women; mean age 44.9 years) who underwent total thyroidectomy without gross residual tumor followed by HDRIA were retrospectively reviewed. Resection margin involvement was evaluated and recurrence of the disease was assessed with clinicopathologically. Recurrence detected within 12 months after HDRIA were defined as early recurrence, detected after 12 months were defined as late recurrence.
RESULTS: The mean follow-up was 85.9 ± 16.6 months. Twelve patients (6.1%) had microscopic cancerous involvement of surgical margin [margin (+) group], and 185 patients had negative surgical resection margins [margin (-) group]. Three patients (25.0%) in the margin (+) group and 11 patients (5.9%) in the margin (-) group had early recurrence. Margin (+) group showed higher incidence of early recurrence and lower incidence of disease free compared to margin (-) group (25.0 vs. 5.9%, p < 0.01; 66.7 vs. 81.1%, p < 0.01, respectively); however, there was no difference in incidence of late recurrence between the two groups (p = 1.00). There were no significant differences in the disease-free survival between the margin (+) and margin (-) groups after exclusion of early recurrence (p = 0.78).
CONCLUSIONS: After high-dose radioactive iodine ablation, PTC patients with microscopic cancerous surgical margin involvement had a higher incidence of early recurrence and no different late recurrence rate compared to patients without microscopic cancerous surgical margin involvement.