Tamoxifen-induced fluorescence as a marker of human breast tumor cell responsiveness to hormonal manipulations: correlation with progesterone receptor content and ultrastructural alterations.

The fluorescent binding of tamoxifen to eosin is used on Papanicolaou-stained smears as a marker of cell responsiveness to the antiestrogen molecule. Forty-two cases of human breast carcinomas were submitted to tamoxifen treatment between first diagnosis and surgery (4 to 30 days). Tamoxifen-induced fluorescence is observed in 17 of 42 cases (40%). There is a highly significant correlation between progesterone receptor content of the tumor and cellular fluorescence (0.01 greater than p greater than 0.001). Ultrastructural changes of such tumors (820 cells observed in 28 treated patients and 840 cells in 32 untreated controls) are observed in 42% of treated cells versus 10% of untreated cells. These ultrastructural alterations can be significantly correlated with cellular fluorescence induced by tamoxifen treatment and with progesterone receptor content of human breast cancers. These data suggest that a short pretreatment with tamoxifen before surgery can give useful additional information at the biochemical, cytochemical, and ultrastructural levels regarding cell responsiveness to hormonal manipulation.