Purpose: To compare the results, in terms of 10-year actuarial survival, between I-131-therapy and I-131-therapy + external beam radiotherapy (RT) in patients operated on for differentiated thyroid carcinoma.
Patients and methods: Over a period of 13 years (1982-1995) 408 patients underwent thyroidectomy with or without linphoadenectomy for pT0/T4 Nx or pN0, pN1a, pN1b thyroid carcinoma. In all cases, thyroidectomy was radical. Patients were divided into two groups, which were comparable according to several prognostic factors: group A composed of 165 patients (surgery + I-131) and group B, 243 patients (surgery + I-131 + RT).
Results: The percentage of deaths related to relapsed or metastatic thyroid carcinoma was 6.25%. In the group treated with adjuvant radiotherapy, 14.8% of the patients experienced acute tracheal or esophageal side effects. Late toxicity (mouth dryness, skin and/or muscle fibrosis) was recorded only in a small percentage of the patients (2.4%).
Conclusions: Adjuvant RT resulted in a statistically significant improvement (p < 0.01) in survival of patients with extracapsular diffusion of the cancer, especially those with pT4 N1b tumors or tumors involving the trachea.