Disease-related death in patients who were considered free of macroscopic disease after initial treatment of well-differentiated thyroid carcinoma

Background: Death from well-differentiated thyroid cancer (WDTC) is rare, and over the past century there has been a trend away from local recurrence as the primary cause of death. The objective of our study was to report the cause of death from thyroid cancer in patients with WDTC treated with curative intent with surgery ± adjuvant radioactive iodine. Methods: An institutional database of 1811 patients with WDTC treated surgically for WDTC between 1986 and 2005 was analyzed and identified 165 (9.4%) who had died. Case records were studied to determine the cause of death in each patient. Results: Of the 165 deaths, 17 (10%) patients were confirmed to have died of thyroid cancer and 6 (4%) died of an unknown cause but had thyroid cancer present at the time of last follow-up. The remaining 142 (86%) died from other causes and were considered free of thyroid cancer at their last follow-up. We therefore identified only 23 cause-specific deaths from the entire cohort (1.3%). Of the 17 patients known to have died of thyroid cancer, all had distant recurrence. Ninety-four percent had pulmonary metastases. Of these, 47% also had bony metastasis at the time of death. Two patients had recurrent disease in the neck at the time of death, but both also had distant disease. Of the six patients (4%) who died of unknown causes but had thyroid cancer at last follow-up, four (67%) had distant disease alone, one (17%) had local and regional recurrence, and one had local and distant recurrence at last follow-up. Conclusion: After successful resection of WDTC, we report a low disease-specific death rate (1.3%). In contrast to earlier reports, death caused by central compartment disease in this recent series is very rare, with metastatic disease accounting for almost all fatalities.