Cellular DNA pattern, S-phase frequency and survival in papillary thyroid cancer.

A series of 150 patients with papillary thyroid cancer diagnosed in Iceland during the 30-year period from 1955 through 1984 was retrospectively analyzed. Flow cytometric analysis of archival paraffin-embedded material was used to study the prognostic significance of cellular DNA content and s-phase frequency. DNA-aneuploidy was found in 12% of the tumors. It was significantly more common in the elderly, in moderately and poorly differentiated carcinomas, in males and in tumors with a high proportion of s-phase cells. Multivariate analysis using stepwise Cox's model showed aneuploidy, age at diagnosis, lymph node metastasis and tumor extension beyond the thyroid capsule as independent prognostic factors. The frequency of cells in s-phase was generally low (mean 2.7%). Patients with high s-phase frequency (greater than 2.5%) had less favorable prognosis than patients with low values (less than or equal to 2.5%).