Thyroid-stimulating immunoglobulin is not associated with aggressive clinicopathologic features in concomitant Graves' disease and papillary thyroid cancer.

[BACKGROUND] Graves' disease has been associated with increased tumor aggressiveness in differentiated thyroid carcinoma, however, its correlation with thyroid stimulating immunoglobulin (TSI) remains unclear.

[METHODS] A tri-institutional retrospective review of 96 thyroidectomy patients with Graves' disease and papillary thyroid carcinoma (PTC) was performed (2002-2020). Clinicopathologic features and recurrence were compared based on TSI level.

[RESULTS] ATA risk stratification distribution was low (72.9 ​%), intermediate (14.6 ​%), and high (12.5 ​%). Recurrence rate was 11.5 ​% with median follow-up of 3.2 years. TSI was not associated with high-risk clinicopathologic features at its 50 ​% and 75 ​% quartiles. There was no difference in median TSI between patients with recurrence versus no recurrence [212 (IQR 98-361) vs. 327 (IQR 152-461), p ​= ​0.148]. TSI was not associated with recurrence on univariable Cox regression, even when excluding microcarcinomas.

[CONCLUSIONS] In this majority low-risk PTC cohort with concomitant Graves' disease, TSI level is not associated with aggressive clinicopathologic features or recurrence.