Does microscopic positive tumor margin in papillary thyroid cancer really matter?

Abstract

Background: The clinical impact of microscopically positive tumor margin in papillary thyroid cancer is not well studied. The aim of this study is to evaluate the clinical importance of a microscopically positive margin for recurrence in papillary thyroid cancer patients and to examine whether recurrence and recurrence-free survival were affected by the location of the positive margin-anterior or posterior.

Methods: We conducted a retrospective cohort study at a single institution. From January 1997 to June 2015,6,293 papillary thyroid cancer patients who underwent total thyroidectomy with or without neck dissection (central and/or lateral) at the Thyroid Cancer Center of Samsung Medical Center (Seoul, South Korea) were included in the analyses.

Results: Of the 6,293 papillary thyroid cancer patients, an operative margin was microscopically involved in 313 (5.0%) on final pathologic report. The mean follow-up time was 77.5 months, and locoregional recurrence was observed in 244 (3.9%) patients. The presence of a microscopically positive margin did not increase the risk of locoregional recurrence (adjusted hazard ratio = 1.079, P = .140) after adjustment for other statistically significant factors in the Cox proportional hazard model. In addition, posterior positive margin was not a risk factor for locoregional recurrence as well (adjusted hazard ratio = 1.24, P = .672). In a propensity score-matching analysis, a microscopically positive margin did not increase the risk of locoregional recurrence.

Conclusion: Microscopic involvement of the operative margin in papillary thyroid cancer patients, whether anteriorly or posteriorly, does not appear be an independent prognostic factor in recurrence-free survival rates.