[Tamoxifen fluorescence as a marker of hormone-dependence: physicochemical aspects].

In acid solutions, Tamoxifen is protonized and forms with eosin a fluorescent ionic association (lambda exc 480 nm, lambda em 565 nm). This reaction is quantitatively linked to the concentration of Tamoxifen. Thus the Tamoxifen induced fluorescence observed in hormone-dependent malignant breast tumor cells after Papanicolaou staining procedure, appears as a consequence of the binding of Tamoxifen to eosin.