Prognostic factors in patients dying of well-differentiated thyroid cancer.

While some well-differentiated cancers of the thyroid gland are unusually aggressive, most have a more benign clinical behavior, making it difficult to evaluate factors possibly influencing patient survival such as initial surgical treatment. By studying 135 patients who received their initial surgical therapy at our institution, we have defined the prognostically significant factors. Sixteen patients (11.9%) died of disease during a ten- to 20-year follow-up period. Significant factors associated with death from disease were aged 40 years or older, primary lesion size of 2.5 cm or greater, presence of invasive characteristics, and presence of distant metastases. We recommend total thyroidectomy and postoperative sodium iodide I 131 therapy in patients 40 years of age or older, while suggesting a less aggressive approach may be appropriate in the younger patients.