Menopausal Hormone Therapy Tied to Less Colorectal Cancer
Sequential estrogen plus progestin in menopausal women linked to largest risk reduction
THURSDAY, Jan. 8 (HealthDay News) -- Hormone therapy during menopause was associated with a lower risk of colorectal cancer, particularly estrogen plus progestin use, according to research published in the January issue of Cancer Epidemiology Biomarkers & Prevention.
Jill R. Johnson, of the University of Minnesota in Minneapolis, and colleagues analyzed data from 56,733 postmenopausal women in the Breast Cancer Detection Demonstration Project follow-up study. The researchers assessed subjects' hormone therapy use from 1979 to 1998. Of this group, 960 women developed colorectal cancer.
The investigators found that ever users of unopposed estrogen therapy had a statistically significant lower risk of colorectal cancer compared to never users (RR, 0.83). Among these women, current users and users with at least 10 years' duration had the largest risk reduction. Sequential users of estrogen plus progestin (women taking progestin less than 15 days a month) had a significant reduction in risk (RR, 0.64), the researchers report. The strongest inverse association in women taking estrogen and progestin was seen in those with past use of at least five years ago (RR, 0.55).
"Despite the recent decrease in use of all menopausal hormones, these results suggest an important protective effect of all hormone formulations, especially estrogen plus progestin, for the many women who continue to need and use menopausal hormone therapy," the authors write. "Several biological mechanisms, via secondary bile acids, insulin-like growth factors, and estrogen and progesterone receptors, have been postulated for the protective effect of menopausal hormone therapy on risk of colorectal cancer."