Flow cytometric analysis of pituitary tumors. Correlation of nuclear antigen p105 and DNA content with clinical behavior.

Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 and DNA content was performed on nuclear suspensions from 12 paraffin-embedded pituitary macroadenomas and one pituitary carcinoma and correlated with clinical outcome. Median follow-up was 41 months (range, 33 to 48 months). Three of the 13 tumors (23%) had an identifiable aneuploid peak. Of the four tumors that recurred or metastasized, only one was aneuploid. Nuclear antigen analysis of all diploid tumors showed enhanced p105 expression in G2M phase cells compared to G0G1 cells. The G2M/G0G1 fluorescence ratio for p105 was consistently higher (P less than 0.05) for the three diploid tumors that recurred (median, 1.32 arbitrary fluorescence units; range, 1.27 to 1.80) than for the seven nonrecurrent diploid tumors (median, 1.20 arbitrary fluorescent units; range 1.14 to 1.22). These findings indicate a low incidence of DNA aneuploidy among pituitary tumors and suggest that for diploid adenomas, measurement of p105 may provide information useful in predicting prognosis and directing postoperative adjuvant therapy.