Flow cytometric monitoring of R 3327 rat prostate carcinoma.

The R 3327 G tumor responds to estrogen in early stages, but relapses when estrogen therapy is continued beyond 50 days postimplantation. Measurement of DNA content per cell by flow cytometric analysis revealed two populations of cells in the tumors with ploidies of 2 c and 3.2 c. The proportion of aneuploid cells (3.2 c), determined from the flow cytometric DNA distributions, correlated well with tumor weight and age in control and estrogen treated animals. The simple parameter of per cent aneuploid cells thus adequately reflected the responsive and unresponsive states of tumors under hormonal therapy.