[Incidence and importance of nuclear estradiol receptors in human breast cancer].

A literature study about the incidence of estradiol receptors in nuclear fractions of human mammary carcinomas and the importance of these receptors for the endocrine therapy were done. Because it is very difficult to isolate purified nuclei from human mammary tumor tissue most of the authors use a crude nuclear fraction (repeated washed 800 g pellet) for the receptor studies. A contamination of the nuclear receptor by receptor proteins of other fractions of the target cell is possible. Occupied (ERn+) and unoccupied (Rn+) nuclear estradiol receptors are demonstrable in more than 50% of tumor tissues with positive cytoplasmic estradiol receptors (ERc+). Both nuclear receptors were often found side by side. Mammary tumor tissues without cytoplasmic estradiol receptor have got seldom nuclear receptors. The response of endocrine therapy, the prognosis and the survival are more favourable in patients with ERc+, Rn+ than in patients with ERc+, Rn-. Regressions after hormone therapy are to expect in about 70% of the patients with ERc+, Rn+. Patients with positive cytoplasmic estradiol- and progesterone receptors have also a response rate of about 70%. An assay of ERc, PgR and Rn appear to reinforce the precision of prediction about prognosis and the kind of therapy in some cases. The use of the DNA-binding of the ERc as marker for the ability of ERc to translocate into the nucleus should be examined further.