Prognostic significance of patient age in minimally and widely invasive follicular thyroid carcinoma: investigation of three age groups.

Follicular thyroid carcinoma (FTC) is the second most common malignancy arising from follicular cells. It is classified into two categories based on the degree of invasion: widely and minimally invasive FTC. Here we focused on the prognostic value of patient age in FTC. We enrolled 292 minimally invasive and 79 widely invasive FTC patients who underwent initial surgery between 1983 and 2007. We classified these patients into three groups based on patient age: < 20 years (children and adolescents), 20-44 years (young adults) and ≥ 45 years (middle-aged or older), and compared their prognoses disease-free survival (DFS) and cause-specific survival (CSS). Among the minimally invasive FTC patients, those aged ≥ 45 years showed a poorer DFS and CSS than those < 45 years. In the subset of patients < 45 years, the DFS of patients < 20 years tended to be poorer than those aged 20-44 years, but none of the patients < 20 years died of FTC. Among the patients with widely invasive FTC, only three were younger than 20 years old. Two patients showed carcinoma recurrence, but neither died of FTC. In minimally invasive FTC, the DFS showed a biphasic pattern, but the CSS became poorer with increasing age. In widely invasive FTC, similar to minimally invasive FTC, patients < 20 years might be likely to show recurrence but are unlikely to die of FTC, although studies using larger number of patients are necessary before drawing any conclusions.