Effect of a half dose of tamoxifen on proliferative activity in normal breast tissue

• Published in: International journal of gynecology and obstetrics 1999-10, Vol.67 (1), p.33-38
• Main Authors: Bernardes, J.R.M, Nonogaki, S, Seixas, M.T, Rodrigues de Lima, G, Baracat, E.C, Gebrim, L.H
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Antineoplastic Agents, Hormonal - administration & dosage; Antineoplastic Agents, Hormonal - pharmacology; Antineoplastic Agents, Hormonal - therapeutic use; Biological and medical sciences; Breast; Breast - cytology; Breast - drug effects; Breast Neoplasms - blood; Breast Neoplasms - drug therapy; Breast Neoplasms - prevention & control; Cell Division - drug effects; Double-Blind Method; Epithelium - drug effects; Female; Fibroadenoma - blood; Fibroadenoma - drug therapy; Fibroadenoma - prevention & control; Gonadal Steroid Hormones - blood; Hormones. Endocrine system; Humans; Medical sciences; PCNA; Pharmacology. Drug treatments; Premenopause; Proliferating Cell Nuclear Antigen - metabolism; Sex hormones; Tamoxifen; Tamoxifen - administration & dosage; Tamoxifen - pharmacology; Tamoxifen - therapeutic use
• ISSN: 0020-7292; 1879-3479
• DOI: 10.1016/S0020-7292(99)00092-2

Objectives: To investigate the proliferative activity of the mammary gland epithelium and plasma levels of progesterone, estradiol, prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and sex hormone-binding globulin (SHBG) in premenopausal women treated with 10 and 20 mg of tamoxifen (TAM) for 22 days. Patients and methods: A randomized double-blind study was performed with 43 premenopausal women with a diagnosis of fibroadenoma of the breast. The patients were divided into three groups: A ( n=15, placebo); B ( n=15, TAM 10 mg/day) and C ( n=13, TAM 20 mg/day). They started taking an oral dose of TAM or placebo on the very first day of the menstrual cycle. Lumpectomy was performed on the 22nd day of therapy. Normal breast tissue samples were collected during surgery, immediately immersed in 10% buffered formalin, processed for routine histology and immunohistochemistry for proliferating cell nuclear antigen (PCNA) detection. Two peripheral blood samples were collected, both on the 22nd day of the menstrual cycle, in order to evaluate the hormone levels. PCNA expressing epithelial cells were quantified by using a digital program Kontron Image System KS-300 in 1000 cells (400×). Results: The percentage of cells expressing PCNA was significantly higher in the group receiving placebo (group A, 50.3%) when compared to groups receiving TAM 10 or 20 mg/day (group B, 24.1%; and group C, 23.2%, respectively) ( P