The Hormone Therapy - Breast Cancer Connection

Hormone Therapy and Breast Cancer Risk

The newest study doesn't provide any information on this -- it simply counted up all women who got breast cancer in 2003, then tried to explain what could account for the big drop from the year earlier. Researchers don't know how many of these women had ever taken hormones.

Some of the best information we have about breast cancer risk and hormone use comes from the Women's Health Initiative (based on 27,000 women), and it seems to depend on which hormones you're using, at what point in menopause you commenced HT, and whether you've had a hysterectomy. Women who have undergone hysterectomy can take estrogen by itself, not in combination with progestin, which seems to be safer for the breasts (estrogen treats menopause symptoms; progestin blunts the harmful effects of estrogen on the uterus).

Women who use the estrogen/progestin combination had a 24 percent higher risk of getting breast cancer if they took this drug combination for five to six years, according to the WHI. But many women in the study were significantly past the age of menopause and had used HT in the past. When researchers looked at those whose breasts had never been exposed to menopause hormones before the study, they found the group had only a 9 percent higher risk of being diagnosed with breast cancer than non-hormone users. Consider that a typical 50-year-old woman has a 2.1 percent risk of breast cancer over the next 10 years. A 9 percent increase would raise her overall risk to just 2.3 percent.

Discuss your level of breast cancer risk with your doctor before taking menopause hormones. Since you can get breast cancer without a family history of the disease, there are no guarantees. "A woman must choose," says Elizabeth Barrett- Connor, MD, chief of the Division of Epidemiology, Department of Family & Preventive Medicine, at the University of California, San Diego, School of Medicine. "Only the risk can be quantified, not the benefit."

If you have a strong family history of breast cancer or have the disease yourself, the doctor will probably veto HT. But not always: "We used to think no women who'd ever had breast cancer should be on estrogen," says Dr. Pisano. "But we have patients to whom we recommend taking estrogens because their menopause symptoms are so terrible."

If you're taking both estrogen and progestin, breast cancer risk doesn't appear to increase until the fourth year of use, according to the WHI. Because of this, most experts suggest that women try to limit their use of the combination hormones to just two to four years. It appears women who use estrogen only have more time. Another major study, the Nurses' Health Study (which has followed more than 120,000 nurses since 1976), found that a woman's risk for breast cancer doesn't increase until after 15 years of use -- far longer than most women would ever need to use hormones.

How long do symptoms last? One study found the average duration of hot flash symptoms among women was four years. Another reported that two-thirds of menopausal women experienced hot flashes for one to five years. The bottom line is that nobody knows if your flashes will last six months, two years, or 10 years, but only a small percentage of women suffer into their 70s.

"The new study should encourage women and their physicians to build in a plan for stopping hormone therapy after one or two years, to see if symptoms persist or have diminished," says Rowan Chlebowski, MD, PhD, a medical oncologist for the Los Angeles Biomedical Research Institute at Harbor UCLA Medical Center and a researcher on both the WHI and new breast cancer incidence studies.

The best advice for women using hormones is to be vigilant about breast self-exams and regular mammograms. Taking menopause hormones may result in an increase in breast density, making a standard mammogram less reliable. If you choose to take menopause hormones, talk to your doctor about having a breast ultrasound in addition to a mammogram, since it does a better job of finding trouble spots in dense breasts.