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A recently published article by Nichols and colleagues [1] provides a detailed analysis of data collected from 10,449 women with invasive breast cancer compared to 11,787 age-matched controls without breast cancer to determine whether the use of estrogen therapy following a bilateral oophorectomy prior to reaching a natural menopause had any influence on the development of breast cancer. In pooled data from the Collaborative Breast Cancer Studies population-based, case–control studies collected between 1992 and 2007, the use of estrogen prescribed for women, following total abdominal hysterectomy with bilateral salpingo-oophorectomy, was analyzed for subsequent development of breast cancer. Case participants were compared with age-matched control cohorts obtained by identifying women in a register of licensed drivers or from a list of Medicare beneficiaries.

 

A very confusing picture emerges from the results. 

1. All women who had their ovaries removed before the age of 40 years were found to have a decreased risk of developing breast cancer – a 24% reduction following estrogen use and 30% reduction when no hormone was used. 

2. Women over the age of 45 years when their ovaries were removed were found to have no reduction in the risk of breast cancer if they used estrogen therapy (but no increased risk).

3. Those women who began estrogen therapy within 5 years of bilateral oophorectomy had a 22% increased risk of breast cancer, whereas those who delayed estrogen use for 5 or more years had a 54% reduction in the risk of breast cancer.

4. Among current estrogen users, those women taking the hormone for less than 10 years had a 32% increased risk of breast cancer, whereas those using estrogen for longer than 10 years had no significant increase in breast cancer.

5. Among current users of estrogen therapy, those who were younger when beginning therapy had a decreased risk of breast cancer while there was an overall increase in breast cancer for older women on estrogen.

Author(s)

  • Barry Wren
    Gynaecological Endocrinologist, Edgecliff Centre, Edgecliff, NSW, Australia

Citations

  1. Nichols HB, Trentham-Dietz A, Newcomb PA, et al. Postoophorectomy estrogen use and breast cancer risk. Obstet Gynecol 2012;120:27-36.
    http://www.ncbi.nlm.nih.gov/pubmed/22914389
  2. Hanahan D, Weinberg R. The hallmarks of cancer. Cell 2000;100:57-70.
    http://www.ncbi.nlm.nih.gov/pubmed/10647931
  3. Sjoblom T, Jones S, Wood LD, et al. The consensus coding sequence of human breast and colorectal cancers. Science 2006;314:268-74.
    http://www.ncbi.nlm.nih.gov/pubmed/16959974
  4. Perez-Losada J, Gonzalez-Sarmiento R. Breast cancer: a stem cell disease. Curr Stem Cell Res Ther 2008;3:55-65.
    http://www.ncbi.nlm.nih.gov/pubmed/18220924
  5. Skinner M. Stem cells: insights into breast cancer heterogeneity. Nature Rev Cancer 2010;10:163-71.
  6. The Cancer Genome Atlas Network. Comprehensive molecular portraits of human breast cancer. Nature 2012; 23 September. Epub ahead of print.
  7. Nielsen M, Thomsen JL, Primdahl S, et al. Breast cancer and atypia among young and middle aged women: a study of 110 medico-legal autopsies. Br J Cancer 1987;56:814-19.
    http://www.ncbi.nlm.nih.gov/pubmed/2829956
  8. Welch HG, Black WC. Using autopsy series to estimate the disease ‘reservoir for ductal carcinoma in situ of the breast. Ann Intern Med 1997;127:1023-8.
    http://www.ncbi.nlm.nih.gov/pubmed/9412284
  9. Dew J, Eden J, Beller E, et al. A cohort study of hormone replacement therapy given to women previously treated for breast cancer. Climacteric 1998;1:137-42.
    http://www.ncbi.nlm.nih.gov/pubmed/11907916
  10. OMeara ES, Rossing MA, Daling JR, et al. Hormone replacement therapy after a diagnosis of breast cancer in relation to recurrence and mortality. J Natl Cancer Inst 2001;93:754-62.
    http://www.ncbi.nlm.nih.gov/pubmed/11353785
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