Apoptosis is a process by which cell death occurs after progressive fragmentation of DNA and that seems to be important in normal and neoplastic tissues. Little is known about the role of apoptosis in the thyroid disease. The aim of this study is to investigate a possible role of apoptosis in growth of well-differentiated carcinoma of thyroid using an in situ nucleotidyl transferase assay (ISNTA), which detects DNA fragmentation, to determine the frequency of apoptosis in nodular goiter (NG), follicular adenoma (FA), follicular carcinoma (FC) and papillary carcinoma (PC). Surgical resection specimens were obtained from 12 patients including NG (n=3), FA (n=2), FC (n=4) and PC (n=3). Positive apoptotic cells (PAC) within the thyroid follicle and neoplastic tissue were counted per section of 1cm². Unpaired t test was utilized to test for statistical significance. The number of PACs were significantly greater (p<0.0001) in NG and FA (24.4±8,2 PAC/cm²) than in FC and PC (1.33±0.82 PAC/cm²). No significant difference was found in the number of PACs between NG and FA and between FC and PC. Apoptosis may play an important role in progression of well-differentiated carcinoma of thyroid gland. This study showed that inhibition of the apoptosis might be implicated in development of the carcinomas of thyroid, considering that the apoptotic index was low in these tumors. Apoptosis, differently from the necrosis, is an active process that could be inhibited or induced, which might have interesting implications for therapy.
Apoptosis; Thyroid; Hyperplasia; Neoplasia; Thyroid disease
