Crescent incidence of papillary thyroid microcarcinoma: 2000--09
Juan A Hernández Bayo1, Mónica Belinchón Sz.-Somoza2, Jose M Hernández Bayo3, Luis Acosta Criado4 & Manuel García Viera5
Objective: Papillary thyroid microcarcinoma (PTM) is a malignant thyroid tumour with potential multifocality and diameter ≤1 cm. Usually is found like incidentaloma, and the epidemiology is not clearly established. We have analysed their epidemiologic in La Palma Island at last 10 years.
Patients and methods: We collected all cases of PTM diagnosed in 345 consecutive thyroid surgeries performed for whichever benign thyroid disease (thyrogloss duct cyst TDC included), at the last 10 years (from 2000 to 2009). Prevalence and incidence were expressed as % and % per year, respectively; and the mean values like mean±S.D. To compare variables, Students t and χ2-tests were used.
Results: Thyroidectomy was performed in 297 females and 48 males with mean age 49.6±15.3 years (485). We found 53 cases of PTM (8 M, 45 F) with mean age 50.9±11.9 years (2578). Just one was diagnosed before thyroidectomy (PTM in a TDC). The PTM prevalence was higher in euthyroid multinodular goitre MNG (20.1%) followed by thyroid solitary nodule (18.2%), toxic adenoma and hypofunctioning MNG (14.3%), Graves disease (10%), toxic MNG (9%) and TDC (3.8%). The mean tumour size was 3.4±2.9 mm. Multifocality was observed in 13.2%. TNM and staging classification according 2006 European Thyroid Cancer Consensus was T1aN0M0 and stage I, respectively, in all subjects. Total prevalence was 15.4% without differences respect to sex (16.7% in M, 15.2% in F). The annual incidence oscilated between 3.3 and 20.8%, showing a striking and progressive increase at the last years (9.8% in 20002004 vs 18% in 20052009, P=0.048).
Conclusions: PTM is more frequent in nodular thyroid disease. The prognosis is excellent in relation to the TNM and staging classification. The prevalence is high, as well as its multifocality, increasing at the last years. It depends on the extended indications for total thyroidectomy for benign diseases, on progress in the field of diagnostic procedures, and on the pathology examination.