Prognostic factors of follicular thyroid carcinoma

Abstract

Introduction: Most prognostic studies in differentiated carcinoma have included a high number of papillary carcinomas and few follicular carcinomas, and not all of their conclusions therefore apply to the latter.

Objective: To analyze the prognostic factors of follicular thyroid carcinoma.

Selection criteria: Patients with histological diagnosis of follicular carcinoma who had undergone potentially curative surgery, had no disseminated disease at diagnosis, and had been followed up for at least 5 years.

Study variables: Tumor recurrence was defined as: 1) tumor lesions with cytological analysis suggesting malignancy and/or 2) patients with total thyroidectomy with thyroglobulin levels >2 ng/mL. Clinical, therapeutic, and histological parameters were analyzed to assess prognostic factors.

Results: Recurrence was found in 25 (38%) of the 66 study patients during a follow-up period of 99 ± 38 months. Most patients with recurrence (n=20) had increased Tg levels without anatomical location, and were initially treated with radioactive I131. In the remaining 5 cases, surgical excision of the lesion was performed, and three patients required surgery during the follow-up period. Two patients died due to the disease (3%), and two other patients (3%) currently have distant metastases. Mean disease-free interval was 154 ± 14 months, and rates of disease-free patients at 5, 10, 15, and 20 years were 71, 58, 58, and 58% respectively. Clinical factors influencing recurrence included 1) age (p=0.0035); 2) sex (p=0.0114); and 3) cervical pain (p=0.0026). Histological/surgical factors associated with recurrence included 1) infiltration into neighboring structures (p=0.0000); 2) type of carcinoma (p=0.0000); 3) size (p=0.0162); 4) vascular invasion (p=0.0085); and 5) adenopathies (p=0.046). In the multivariate study, cervical pain (p=0.018) and extrathyroid invasion (p=0.045) continued to be significant factors.

Conclusions: In follicular carcinoma, rates of disease-free patients are 71% at 5 years and 58% at 10 years, and the main predictive factors are presence of local clinical symptoms and infiltration into neighboring structures.

Keywords: Ampliamente invasivo; Carcinoma folicular; Diferenciación; Differentiation; Factores pronósticos; Follicular carcinoma; Invasion; Invasive; Invasión; Minimally invasive; Mínimamente invasivo; Prognostic factors; Thyroid gland; Tiroides.