UCSF

Background

Incomplete surgical resection with gross positive tumor margin increases the risk of recurrence in patients with well-differentiated thyroid cancer (WDTC); however, it is not clear whether a microscopic positive margin found only on final pathology has similar implications on patient outcomes.

Methods

We conducted a single-institution retrospective review of all patients undergoing total thyroidectomy for T1-T2 WDTC (January 2000-January 2010). Factors that may influence the risk of locoregional recurrence or distant metastasis were evaluated by univariate and multivariate analysis.

Results

Of 1000 consecutive patients undergoing surgical resection for WDTC, 684 T1-T2 cancers were included. Mean age was 46 years and 81 % were women. Of this total cohort, 78 (11 %) patients had microscopic positive margins. Radioactive iodine (RAI) was administered in 47/78 (60 %) patients with positive margins versus 312/606 (51 %) patients without positive margins. After a mean follow-up of 46 months, 53 (8 %) patients developed recurrent disease (1 local and 52 nodal). On multivariate analysis, nodal metastases (N1, odds ratio [OR] 7.7) and contralateral multifocality (OR 3.7) were independent risk factors for recurrent disease. A microscopic positive margin was not a risk factor for recurrence.

Conclusions

A microscopic positive margin found only on final pathological analysis does not increase the risk of recurrence in T1-T2 WDTC. Clinicians should interpret such pathology findings accordingly when considering further surveillance and treatment decisions such as the use of RAI ablation.