Background: The rate of unexpected thyroid cancers found at the time of thyroidectomy is thought to be similar in patients with cervical and substernal multinodular goiters (MNGs).
Methods: The objective of this study was to compare the prevalence of undiagnosed cancer found in patients undergoing a thyroidectomy for a cervical or substernal MNG. We conducted a review of patients with a preoperative diagnosis of an MNG (both cervical and substernal) at a tertiary referral center between 2005 and 2012.
Results: We identified 538 patients who underwent thyroidectomy for an MNG (144 with substernal MNGs and 394 with cervical MNGs). Patients with substernal MNGs were older (59.6 vs. 52.3; p < 0.001), more likely to be men (34 vs. 11.1 %; p < 0.001), and less likely to have a history of radiation exposure to the neck (2.1 vs. 12.4 %; p < 0.001). Thyroid cancer (>1 cm) was found in 13.7 % of substernal MNG specimens and in 6.3 % of cervical MNG specimens (p = 0.003). On multivariate analysis, substernal location [odds ratio (OR) = 2.360; confidence interval (CI), 1.201-4.638] was the only variable independently associated with an unexpected thyroid cancer on surgical pathology.
Conclusion: The rate of postoperatively discovered thyroid cancer is significant in patients with substernal MNGs and is increased when compared to patients with cervical MNGs. Surgeons should counsel their patients regarding the possibility of this unexpected result.