KI-67 IMMUNOSTAINING OF ENDOMETRIAL BIOPSIES WITH SPECIAL REFERENCE TO HORMONE REPLACEMENT THERAPY

Background. The purpose of this investigation was to evaluate the Ki-6 7 immunostaining method on formalin-fixed, paraffin-embedded endometri um and to use the method on endometrial biopsies from 30 postmenopausa l women treated with 2 mg estradiol and different doses of natural mic ronized progesterone (50, 100 or 200 mg). Methods. Two technicians pre pared the immunostaining of slides from each of 12 endometrial specime ns and 3 different observers estimated the Ki-67 immunostaining. One o bserver estimated all the slides 3 times on different occasions. The p ercentage of immunopositive nuclei in glandular epithelium was evaluat ed. Results. The dominating component of variation for this method was between observers, with a median standard deviation of 20%. A total m edian variation including all components rendered a standard deviation of 23%. No significant effects of different technicians, preparations , or from the same observer on different occasions were found. In the major part of the biopsies from women on hormone replacement therapy ( HRT), only 0-10% of the glandular epithelium was Ki-67 stained. Conclu sion. Ki-67 immunostaining is an adequate technique to use when evalua ting the effects of HRT on the endometrium. The main source of variati on is between observers and not the technique of preparing the slides.