Study Reinforces Link Between Hormone Therapy, Breast Cancer

Dorian Martin Health Guide
  • Having severe menopausal symptoms? Thinking about taking hormone therapy to deal with them? If you are, you need to be aware that yet another study has highlighted the increased risk of breast cancer that comes with taking estrogen and progestin therapy.


    This new study involved 41,449 postmenopausal women who had not experienced a hysterectomy and did not have a mammogram negative within two years of the study’s start. Of these, 25,328 were not using hormones while 16,121 used hormone therapy (estrogen and progestin). None of the women in this study participated in estrogen-only therapy, which is used by women who have had a hysterectomy.

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    The researchers checked back in with these women after an average of 11 years and found 2,236 diagnoses of breast cancer. Their analysis found that the incidence of breast cancer was higher in women who used both estrogen and progestin than in women who didn’t use hormones. Furthermore, women who started using hormone therapy close to menopause had a higher risk of breast cancer. “Women starting within months of menopause had about a threefold greater risk than women starting 10 years after menopause,” said Dr. Rowan Chelbowski, a medical oncologist at the Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles Medical Center and the study’s lead researcher.

    These findings were consistent with the Women’s Health Initiative’s randomized trial. In that study, about one-third of the study participants were in their 50s at the onset of the research. The other two-thirds were in their 60s or beyond and, thus, having completed the menopausal transition. As part of that study, those women began taking hormones several years after their last menstrual period. The participants were assigned to two treatment groups as part of the study.

    In trying to see if the link between the risk of breast cancer changed based on taking hormones at an earlier date, Dr. Chlebowksi’s team compared their findings with the WHI findings. The team found that the risk of breast cancer increased more if women were nearer to their menopausal change when they started the hormones. They hypothesized that  hormone therapy may serve hormonal trigger for women who are close to the menopausal transition because they still have some levels of hormones (estrogen and progestin) in their bodies.

    However, there are some benefits of hormone therapy. The National Cancer Institute (NCI) reported that studies have found that combined hormone therapy provides the following benefits:

    • Fewer hip and vertebral fractures. One study found that women who took this type of therapy had one-third fewer fractures of these types than women who were taking a placebo.
    • Lower risk of colorectal cancer. A study also found that women taking this type of therapy had a one-third lower risk of this type of cancer.

    However, researchers determined that these benefits stopped once the participants ended combined hormone therapy medication.

  • There are also some benefits of taking estrogen only. The NCI reported the following:

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    • Fewer hip and vertebral fractures. Again, women who took this type of therapy had one-third fewer fractures than women who took the placebo.
    • Reduced risk of breast cancer, Researchers found a 23-percent reduced risk of breast cancer among women who took this type of therapy.

    The NCI noted that when researchers followed up with study participants almost 11 years later, the risk of hip fractures was slightly higher in women who took estrogen-along therapy. However, the risk of breast cancer for these women remained lower than those women who took the placebo.

    However, there are risks beyond breast cancer for these therapies. Menopausal hormone therapy with estrogen alone increases the risk of endometrial cancer in women who have not had a hysterectomy.  And therapy that includes estrogen and progestin is associated with urinary incontinence, dementia, stroke, blood clots and heart attack.

    So what should women do? If you’re experiencing severe menopausal symptoms, talk with your doctor about what you can (and should do). If you are considering hormone therapy, most of the experts say to take the lowest dosage for the shortest period of time. Again, it’s important to talk to your own doctor to determine what’s right for you.

    Primary Sources for This Sharepost:

    Chlebowski, R. T., et al. (2013). Estrogen plus progestin and breast cancer incidence and mortality in the Women’s Health Initiative Observational Study. Journal of the National Cancer Institute.

    MedlinePlus. (2013). More evidence shows hormone therapy may increase breast cancer risk.

    National Cancer Institute. (2011). Menopausal hormone therapy and cancer.

Published On: April 03, 2013