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A recently published paper by DeLellis Henderson and colleagues [1] evaluated the risk of colon cancer associated with the duration and recency of specific menopausal hormone therapy formulations: unopposed estrogen versus estrogen combined with progestin among 56,864 peri- and postmenopausal women who were participating in the California Teachers Study, a prospective study during 1995–2006 (mean age at recruitment around 62 years; 76% reported ever using hormone therapy (HT), 61% were current users). Altogether, 442 incident invasive colon cancer cases were diagnosed. The paper confirmed a number of observations that have been previously reported in the literature. First, a 36% reduced risk was documented among baseline (recent) hormone users compared with baseline never-users (hazard ratio (HR) 0.64, 95% confidence interval (CI) 0.51–0.80). Results did not differ by formulation of HT. Sub-analyses showed the following: 


1. The highest reduction in risk was seen in women reporting on 5–15 years of recent HT use at baseline (HR 0.49, 95% CI 0.35–0.68).When hormonal treatment was used for more than 15 years, attenuation of protection against developing colon cancer was stronger in the recent-user groups of combined estrogen + progestin than in the recent users of estrogen-only therapy.

2. Women with a family history of colon cancer gain a greater protection against the disease compared to women who do not have such family history.

3. Estrogen-only therapy confers more protection than estrogen combined with a progestin.


  • Farook Al-Azzawi
    Menopause Research Unit, University Hospitals of Leicester, Leicester, UK


  1. Delellis Henderson K, Duan L, Sullivan-Halley J, et al. Menopausal hormone therapy use and risk of invasive colon cancer: the California Teachers Study. Am J Epidemiol 2010;171:415-25. Published February 15, 2010.
  2. Slattery ML, Samowitz WS, Holden JA. Estrogen and progesterone receptors in colon tumors. Am J Clin Pathol 2000;113:364-8
  3. Castiglione F, Taddei A, DeglInnocenti DR, et al. Expression of estrogen receptor beta in colon cancer progression. Diagn Mol Pathol 2008;17:231-6.
  4. Foley EF, Jazaeri AA, Shupnik MA, et al. Selective loss of estrogen receptor beta in malignant human colon. Cancer Res 2000;60:245-8.
  5. English MA, Hughes SV, Kane KF, et al. Oestrogen inactivation in the colon: analysis of the expression and regulation of 17beta-hydroxysteroid dehydrogenase isozymes in normal colon and colonic cancer. Br J Cancer 2000;83:550-8.
  6. English MA, Kane KF, Cruickshank N, et al. Loss of estrogen inactivation in colonic cancer. J Clin Endocrinol Metab 1999;84:2080-5.
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