Review of thyroid cancer cases among patients with previous benign thyroid disorders

A previous register linkage study showed an increased risk of thyroid cancer among patients previously discharged from a hospital with a diagnosis of a benign thyroid disorder. In this study, we have reviewed all available medical records, first to validate the earlier result and second to describe the symptomatology of patients with a history of benign thyroid disorder prior to the cancer diagnosis. The previous study identified 189 patients with a benign and subsequent malignant thyroid disorder. Medical records were obtainable for 156 of these patients and were reviewed. For 104 patients, benign and malignant thyroid diseases were metachronous (a clearly separated disease history of the benign and malignant diseases), and for 48 patients synchronous. In 4 cases, thyroid cancer could not be confirmed. Among patients with metachronous thyroid disorders, all major benign thyroid disorders were represented including hot nodules, diffuse and multinodular toxic and nontoxic goiter. Symptoms preceding diagnosis of thyroid cancer included growth of goiter/nodules, globulus, stridor, hoarseness, and metastasis. No major differences were found among patients with metachronous and synchronous benign and malignant thyroid disorder, apart from the fact that all metastases were found among metachronous cases. This study confirmed the conclusion that patients with a previous history of goiter or nodules have an increased risk of thyroid cancer. However, thyroid cancer still occurs too infrequently to warrant screening in all patients with a previous history of goiter or nodules.