The value of DNA content in predicting the prognosis of thyroid carcinoma in an endemic iodine deficiency region.

DNA content of tumour was found to correlate with various prognostic factors and survival, especially in well differentiated thyroid carcinoma. The aim of this investigation was to evaluate the correlation between the DNA ploidy and the prognosis as well as the survival in thyroid carcinoma in our country, being an endemic iodine deficiency region. DNA flowcytometry was performed on paraffin embedded archival tissue blocs of 74 patients with thyroid carcinoma (70 well differentiated, 3 anaplastic and Hurthle cell carcinoma) and 12 patients with multinodular goitre. DNA ploidy was defined as diploidy or aneuploidy. Aneuploidy was detected in 5 (6.8%) patients with thyroid carcinoma (3 anaplastic, 1 papillary and 1 Hurthle cell carcinoma). Aneuploidy was significantly more frequent in patients with anaplastic carcinoma (n: 3/3, 100%) compared to well differentiated thyroid carcinoma (n: 1/70, 1.4%) (p < 0.0001). Aneuploid DNA content significantly correlated with advanced age (p < 0.01), large tumour size (p < 0.001), and low survival (p < 0.01). Mean survival period of patients with anaplastic carcinoma in whom aneuploidy was frequently encountered, was shorter compared to patients with diploid well differentiated tumours (p < 0.01). In conclusion, although anaplastic and follicular carcinoma are more frequently diagnosed in endemic areas, the rate on aneuploidy was found to be lower in thyroid carcinoma in our country compared to data reported to nonendemic areas. As the prognostic predictive value of DNA ploidy is reliable in well differentiated thyroid carcinoma, DNA measurement of FNA biopsy may influence the extent of surgery. Thyroid carcinoma, other than well differentiated types, require radical operations independent of the DNA content. However, adjunctive treatment methods may be used earlier postoperatively according to quantitative DNA measurement.