Effect of combined oral contraceptives on breast epithelial proliferation in young women

Effect of combined oral contraceptives on breast epithelial proliferation in young women

Author Garcia y Narvaiza, Debora Autor UNIFESP Google Scholar
Navarrete, Maria Alicia H. Autor UNIFESP Google Scholar
Falzoni, Roberto Google Scholar
Maier, Carolina M. Google Scholar
Nazario, Afonso C. P. Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Stanford Univ
APC Pathol
Abstract The mammary gland undergoes morphologic changes during the menstrual cycle. Proliferation of normal breast epithelium is most extensive during the natural luteal phase. To determine the impact of one cycle of a combined oral contraceptive (COC) on breast homeostasis, we evaluated the proliferation index (PI), determined by KI-67 expression, in normal human mammary epithelial cells and correlated it with cellular proliferation in spontaneous menstrual cycles during the same period. Normal breast tissue samples were obtained from 82 patients randomized in two groups. Forty-two women in group A received one cycle of a COC (30 mu g ethinyl estradiol and 150 mu g levonorgestrel) administrated daily for 21 days, beginning on the first day of the menstrual cycle. Group B patients (n = 40) experienced a natural menstrual cycle. Menstrual cycle phase characterization was based on the date of the last period and subsequent menses and on progesterone serum levels obtained at the time of biopsy. the PI (number of Ki-67-positive nuclei per 1,000 epithelial cells), was significantly larger in group A (5.47 +/- 3.87), than in group B (3.27 +/- 3.24), p < 0.01. A cyclical variation of PI was observed in COC cycles. the rise in PI in the first week of the COC cycles was significantly higher than in the natural cycle (COC = 7.02 +/- 4.94; non-COC = 1.10 +/- 0.67; p < 0.0011). There was no significant difference between the two groups during the other weeks. Additionally, there was an inverse correlation between proliferation and chronological age, irrespective of the stage of the cycle. the PI of COC (p = 0.175) and natural cycles (p = 0.466) were not statistically different in younger patients. COC users have increased proliferative activity at the beginning of the menstrual cycle. This alteration in the pattern of proliferative activity may relate to the increased risk of breast cancer that has been associated with COCs.
Keywords combined oral contraceptives
Ki-67
mammary gland
menstrual cycle
Language English
Sponsor Federal University of São Paulo
Date 2008-09-01
Published in Breast Journal. Oxford: Blackwell Publishing, v. 14, n. 5, p. 450-455, 2008.
ISSN 1075-122X (Sherpa/Romeo, impact factor)
Publisher Blackwell Publishing
Extent 450-455
Origin http://dx.doi.org/10.1111/j.1524-4741.2008.00621.x
Access rights Closed access
Type Article
Web of Science ID WOS:000258978800007
URI http://repositorio.unifesp.br/handle/11600/30897

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