title: A pilot study of the effects of short-term tamoxifen therapy on Ki-67 labelling index in women with primary breast cancer.
abstract: In this study we demonstrate the change in estrogen receptor (ER) level and cell proliferation in human breast cancer after a short-term tamoxifen therapy. Ten pre- and post-treatment breast tumor samples were examined immunohistochemically using ER and Ki-67 antibodies. Before tamoxifen treatment, six (60%) of ten patients were positive for ER. Tamoxifen increased the ER level in one patient and decreased the level in 4 patients. There was no significant change in ER level by tamoxifen therapy. On the other hand, Ki-67 labelling index (LI) significantly decreased after tamoxifen treatment. When Ki-67 LI was analyzed according to ER level, there was no difference between pre- and post-tamoxifen treatment in ER-negative patients, however, a significant decrease of Ki-67 LI by tamoxifen treatment was seen in ER-positive patients. Patients who showed down-regulation of ER expression tended to show a decrease of Ki-67 LI after tamoxifen therapy. In conclusion, short-term tamoxifen therapy decreased the proliferation of breast cancer, in ER-positive breast tumor samples.
authors.affiliation: Department of Gynecology, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil.
authors.forename: R D
authors.initials: RD
authors.lastname: Dardes
authors.forename: J
authors.initials: J
authors.lastname: Horiguchi
authors.forename: V C
authors.initials: VC
authors.lastname: Jordan
mesh_terms: D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology* / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000096:biosynthesis* / Q000187:drug effects; D008875:Middle Aged; D010865:Pilot Projects; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D019394:Ki-67 Antigen; D011960:Receptors, Estrogen; D013629:Tamoxifen