Does microscopically involved margin increase disease recurrence after curative surgery in papillary thyroid carcinoma?

Background The prognostic significance of microscopically involved margin in papillary thyroid carcinoma (PTC) following curative surgery remains unclear. We aimed to evaluate the impact of an involved margin and its location (anterior vs. posterior) on disease recurrence. Methods Of the 638 eligible patients, 538 (85.9%) did not have an involved margin (group I) while 100 (14.1%) did (group II). The latter group was further classified according to its location relative to the surface of the thyroid gland (anterior or posterior). A multivariate analysis was conducted to identify independent factors for recurrence risk. Results After a mean of 130.1 ± 93.5 months, 22 patients had disease recurrence. The 10‐year disease‐free survival (DFS) was significantly worse in group II (95.0% vs. 97.0%, P = 0.011). After adjusting other significant factors, involved margin was not an independent risk factor for disease recurrence ( P = 0.358). Compared to a negative margin, an anterior involved margin did not pose increased recurrence risk (HR = 1.21, 95%CI = 0.93–500.00, P = 0.368), whereas a posterior involved margin had almost 23 times higher recurrence risk (HR = 22.95; 95%CI = 4.33–121.70, P < 0.001). Conclusions Overall, a microscopically involved margin was not an independent factor for DFS. However, although an anterior involved margin itself did not increase disease recurrence, a posterior involved margin did. J. Surg. Oncol. 2016;113:635–639 . © 2016 Wiley Periodicals, Inc.