Incidental Thyroid Cancer in Patients With Graves' Disease: Not as Rare as We Previously Believed

The incidence of thyroid cancer in Graves' disease (GD) patients remains unclear due to the limitations of previous studies which mostly include small, single-institution cohorts. We used the large, multi-institutional National Surgical Quality Improvement Program's Procedure Targeted Thyroidectomy dataset to explore the rate of incidental thyroid cancer in Graves' patients undergoing total thyroidectomy.

We identified patients who underwent total thyroidectomy for GD in the National Surgical Quality Improvement Program's Procedure Targeted Thyroidectomy between 2013 and 2021. Surgical pathology reports were reviewed for coexisting thyroid cancer, excluding occult or microconfined cases. Demographic and postoperative outcomes were compared for patients with and without incidental cancer.

Of 3193 GD patients treated surgically, 406 (12.7%) had incidental thyroid cancer on final pathology. Among those with cancer, 387 (95.3%) had papillary thyroid carcinoma, 14 (3.4%) had follicular cancer, and 1.3% had Hürthle cell cancer or metastasis from other primaries. On pathology, 343 (84.5%) had T1 disease, 23 (5.7%) T2, and 16 (3.9%) T3, while 26 patients (6.4%) had N1 disease. Most cancers were solitary and unilateral (61.6%), however, 12.6% had multifocal unilateral disease, and 19.2% had multifocal bilateral disease. Graves' patients with cancer were older (median age 47.0 versus 42.0, P < 0.01) and had a higher body mass index (median body mass index 28.9 versus 27.8, P < 0.01) at the time of surgery, with no difference in postoperative outcomes.

Thyroid cancer was incidentally found in 12.7% of patients undergoing thyroidectomy for GD. This risk should be considered when counseling patients on definitive management of GD.