Differentiated thyroid carcinoma

Abstract

The optimum treatment for differentiated thyroid carcinoma (DTC) is still debated. Results obtained using a selective treatment strategy for papillary (PTC) and follicular (FTC) thyroid carcinoma over 25 years in one institution are reported. 149 patients (mean age 46 yrs) had PTC in TNM stages I-IV in 58%, 26%, 15% and 1% respectively. Total thyroidectomy and remnant 131I ablation (43%) were carried out in TNM high-risk patients (stages III and IV) and in low-risk patients (I and II) at risk for a (curable) recurrence (stages pN1 and/or pT4). Hemi- or total thyroidectomy, without radioiodine, was used in 76% of pT1-3 N0 tumours (68%). Central and/or lateral lymphadenectomy was performed in 42% of patients (electively in the last 4 years). The mean follow-up was 7 years. Results: 6 patients died of PTC and 8/143 patients treated for cure had a recurrence (6 nodal, 1 contralateral, 1 local). In low-risk patients - Including 68% of patients aged ≥45 yrs - The cause specific 25-year survival rate was 100%, vs. 62% (at 15 years) (p <0.0001) in high-risk patients. In stage I and stage II the recurrence-free survival rates at 25 years were 95% and 100% respectively. Risk factors for recurrence were macroscopic (p<0.0001) but not microscopic local invasion (pT4); stage pN1 (p = 0.0004). Only 1/107 patients initially judged node-negative had a nodal recurrence. FTC (n = 115; mean age 56 yrs; mean follow-up 8 yrs): Cause-related death (n = 8) or serious recurrence (n = 3) occurred in 10/53 grossly invasive FTC, in 1/45 minimally invasive FTC with vascular invasion, and in none of 17 FTC with capsular invasion (CI) alone, under radical treatment (131I) in 75%, 33%, and 12% respectively. 20-year disease-free survival in grossly and in minimally invasive FTC was 78% and 95.5% respectively (p = 0.0007). Patients aged <45 yrs and patients with minimally invasive FTC with CI alone (all ages) had 100% 20-year disease-free survival vs. 80% (p = 0.013) in the remainder. There was no curable recurrence in FTC. The ratio of grossly invasive FTC decreased (p <0.0001) during the study period. Conclusions: - Risk-0 groups may be defined and selected for a reduced extent of treatment (PTC pT1-3 N0; FTC <45 yrs, or CI alone). - Older (≥45 yrs) patients with PTC in stages I and II have an excellent prognosis (risk 0). - With selective (therapeutic) lymphadenectomy the risk of nodal recurrence may be very low in node negative tumours, without use of radioiodine. Meticulous lymphadenectomy is indicated in pN1 tumours with nodal recurrences despite 131I (5/36 patients). - The technique of capsular dissection for extra-capsular total uni- or bilateral thyroidectomy provides excellent oncological and surgical results. - A decrease in the incidence of FTC parallels a decrease in endemic goitre in Switzerland.