Influence of surgical and postoperative treatment on survival in differentiated thyroid cancer

Abstract

Background: The extent of thyroidectomy in patients with differentiated thyroid cancer (DTC) remains controversial. The aim of this study was to identify how surgical technique and postoperative treatments influence survival and locoregional recurrence in DTC. Methods: A nested case-control study was conducted in a cohort of 5123 patients diagnosed with DTC in Sweden between 1958 and 1987. One matched control subject was selected randomly for each patient who died from DTC. Details regarding surgery and postoperative treatments were obtained from medical records. The effect of treatment on survival was estimated by conditional logistic regression. Results: Patients not treated surgically had a poorer prognosis, but the risk of death from DTC was not affected by the choice of surgical technique. The extent of surgery influenced survival only in patients with TNM stage III disease. Locoregional recurrence resulted in a fivefold increased risk of death. Postoperative treatment was not associated with improved survival. Conclusion: In operated patients, the most important prognostic factor was complete removal of the tumour. The extent of removal of remaining thyroid tissue was of prognostic importance in stage III disease only. Adjuvant postoperative treatment did not influence the prognosis favourably.