Changes in TNM stage, reoperation and 131‐I ablation rate during the use of newer methods for the preoperative diagnosis of differentiated thyroid carcinoma

Summary Objective  To define and discuss the changes of important risk factors and TNM staging over the last 40 years in patients operated on for differentiated thyroid carcinoma (DTC), resulting from the introduction of newer sensitive diagnostic procedures in the preoperative evaluation of thyroid nodules. Patients  We reviewed the medical records of 1251 patients with postoperative diagnosis of DTC who had undergone initial diagnosis, before surgery, at our unit, between 1971 and 2010. According to the period of diagnosis, the patients were divided into four groups (I, II, III, IV) corresponding to the four decades. Results  The mean age at diagnosis was unchanged over time for both papillary (PTC) and follicular thyroid cancer (FTC). A decrease in the proportion of FTC (group I vs group IV P < 0·01) and a concomitant increase in PTC/FTC ratio was observed particularly in group IV. The significant decrease in the proportion of tumour size of PTC (group I vs group IV, P < 0·01), the increase in the proportion of microcarcinomas, from 22·4% in group I to 53·0% in group IV, P < 0·001, and the decrease in the number of cases with features of aggressiveness have changed the TNM stage towards stages I and II. The overall frequency of patients at high risk was significantly decreased, from 8·0% in group I to 1·8% in group IV. The number of patients who underwent reoperation for the completion of tumour resection and/or radioiodine therapy significantly decreased over time. Conclusions  The evaluation of thyroid nodules using the newer diagnostic methods was useful in identifying DTC early. Consequently, the reoperation and thyroid remnant ablation rates were reduced.