DNA ploidy and stromal bone formation as prognostic indicators of thyroid papillary carcinoma in aged patients: a retrospective study.

The prognostic value of flow cytometry for thyroid papillary carcinoma in aged patients was studied and compared with that of tumor histology. Seventy-five surgically removed primary papillary thyroid carcinomas larger than 30 mm in diameter were obtained from patients over 60 years of age. A subtotal thyroidectomy with modified radical neck dissection was performed in all patients. Sixteen female patients died of the carcinoma (non-survivors) and 18 survived longer than 12 years without recurrence (survivors). Histologically, papillary carcinoma was subclassified into poorly and well differentiated types, and the presence of stromal bone formation was noted. Flow cytometry was performed using paraffin-embedded materials. The incidence of the poorly differentiated type was 2/18 among the tumors of survivors and 6/16 among the tumors of non-survivors (P = 0.08). Stromal bone formation was only found in the tumors of the survivors (6/18 and 0/16; P = 0.014). In flow cytometry, tumors of the survivors showed a DNA diploid pattern (14/14), whereas half of the tumors of non-survivors (6/12) showed an aneuploid pattern (P = 0.004). Moreover, in the remaining six tumors of the non-survivors, two showed a third peak at 6C and one showed a higher S fraction. Therefore, only three showed a DNA diploid pattern that was indistinguishable from that of the survivors. These results suggest that flow cytometry is useful for estimating the prognosis of thyroid papillary carcinoma.