Differentiated thyroid cancer: prognostic factors and influence of treatment on the outcome in 441 patients

Differentiated thyroid cancer (DTC) is a rare tumor entity with excellent prognosis. Thus, assessment of the efficacy of different treatment modalities requires follow-up for such a long period that the validity of the conclusion may be limited because diagnostic and therapeutic standards have changed substantially. Accordingly, the indication for external radiotherapy is still controversial. The aim of the present retrospective study is to evaluate prognostic factors and the influence of treatment on outcome of differentiated thyroid cancer from a large data base. Patients and Methods: Records of 441 patients (317 females, 124 males; mean age 46 years) with 270 follicular and 171 papillary thyroid carcinomas (pT1–4, pNO-3) were reviewed. Treatment was surgery in 440, radioiodine therapy in 338, postoperative external radiotherapy (50–60 Gy) in 223 patients. In 182 cases the three modalities were combined. Results: The 5-year actuarial survival rate of the whole study population was 95%, 10-year survival 92%. 10-year survival was significantly influenced by: tumor stage (pT1: 100%, pT2: 94%, pT3: 94%, pT4: 79%; p = 0.0005), age ( 60 years: 79%; p = 0.0001) and the presence of lymph node metastases in the follicular subtype (pNO: 96%, pNO1–3: 81%; p = 0.02). No significant differences in survival were found according to gender or histological subtype. External radiotherapy yielded a non-significant (p = 0.06) increase in the 10-year survival rate (87% vs 46%; p = 0.06) in patients with pT4 tumors (n = 60). Conclusion: Prognostic factors predominantly confirmed those reported in the literature. Further clinical studies should clarify, if the trend towards better survival in irradiated patients with pT4 tumors can be confirmed in larger patient groups.