Supplementary Material for: Thyroid incidentalomas; incidence and oncological implication in patients with esophageal cancer

Thyroid incidentalomas are often encountered during imaging performed for the workup of esophageal cancer. Their oncological significance is unknown. This study aimed to establish incidence and etiology of thyroid incidentalomas found during the diagnostic workup of esophageal cancer. All esophageal cancer patients referred to or diagnosed in the Amsterdam UMC between January 2012 and December 2016 were included. Radiology and multidisciplinary team meeting reports were reviewed for presence of thyroid incidentalomas. When present, the 18FDG-PET/CT or CT was reassessed by a radiologist. Primary outcome was the incidence and etiology of thyroid incidentalomas. In total, 1,110 esophageal cancer patients were included. Median age was 66 years, most were male (77.2%) and had an adenocarcinoma (69.4%). For 115 patients (10.4%) a thyroid incidentaloma was reported. Two thyroidal lesions proved malignant. One esophageal cancer metastasis (0.9%) and one was a primary thyroid carcinoma (0.9%). Only the primary thyroid carcinoma resulted in treatment alteration. The other malignant thyroid incidentaloma was in the context of disseminated esophageal disease and ineligible for curative treatment. In this study, thyroid incidentalomas were only very rarely oncologically significant. Further etiological examination should only be considered in accordance with the according to the TI-RADS classification system and when clinical consequences are to be expected.