Birth Control Pill Raises Breast Cancer Risk for Some

Study finds younger women with a gene face higher odds of disease 

Women who have one of the breast cancer genes and take oral contraceptives for five or more years increase their risk of developing early-onset breast cancer, a new study finds. 

Researchers looked at the history of birth control pill use in 2,600 women who had mutations in either the BRCA1 or BRCA2 gene, the so-called cancer susceptibility genes. Half of them had developed breast cancer and half had not.

Increased Breast Cancer Risk Found Among BRCA1 Carriers Taking Oral Contraceptives

Women with BRCA1 mutations—but not BRCA 2—who used oral contraceptives for five or more years had a 33 percent increase in breast cancer risk compared with BRCA1 carriers who had never used the pill, says study author Dr. Steven A. Narod, a professor and chairman of breast cancer research at the University of Toronto. The research appears in a recent issue of the Journal of the National Cancer Institute.

Narod's team also found an elevated risk in those BRCA1 carriers who used the pill before age 30 and who first used oral contraceptives before 1975, when typical doses were higher than in more recent formulations. The longer they used the pill, the higher the risk.

The average age of diagnosis for the women with BRCA1 gene mutations who developed breast cancer was 38.6.

Narod puts the elevated risk in perspective this way: In the general population, women have a 9 percent lifetime risk of breast cancer. "Women who are BRCA1 carriers and do not take the pill ever have about a 60 percent lifetime chance of breast cancer," he says. "Women who are BRCA1 carriers and do take the pill for five years have an 80 percent chance. That's my interpretation of our findings."

To incur the increased risk, he adds, they had to begin taking it before age 25.

Facing Tough Decisions About Oral Contraceptive Use

Women who carry the genes face tough decisions about oral contraceptive use. Research suggests long-term use of the pill is associated with a modest increase in the risk of early-onset breast cancer even in the general population, but oral contraceptives are also found to be protective against ovarian cancer risk, which has also been found to be elevated among those with the breast cancer mutation genes.

Other experts praise the study and say it will give them something solid to point to when they are asked about the best course of action for BRCA1 and BRCA2 carriers.

"It's a very large study, and that makes the information more applicable," says Monica Alvarado, a certified genetic counselor at the University of Southern California/Norris Comprehensive Cancer Center in Los Angeles. The women were recruited from 52 genetic testing centers in 11 countries. "Prior to this, we were able to tell women [with the gene mutation] that taking the birth control pill reduces ovarian cancer risk but we didn't know what it meant for breast cancer risk. All we could say was there was a suspicion [that it increased risk]."

"We always have to be careful [about making recommendations] based on one study," Alvarado says. "But it's the first time we have any real data from a large study to present to our patients."

Leslie Bernstein, an epidemiologist and professor of preventive medicine at the University of Southern California Keck School of Medicine, calls the study a critical paper. "It's what we would have predicted based on other [smaller] studies, including one we did," she says.

"It's a very well-done study," adds Bernstein, who has studied the association between physical activity and cancer reduction risk for several years. Like Alvarado, she is reluctant to make recommendations based on one study. But she says the new research should provide useful information to women who have the BRCA1 mutation in making contraceptive and other life choices.

Always consult your physician for more information.

HRT Raises Risk of Lobular Breast Cancer

Study ID's type of tumor tied to combined therapy

The National Institutes of Health (NIH) pulled the plug on a massive study earlier this year after women taking combined hormone therapy were found to have an increased incidence of breast cancer.

Now a new study has identified which type of breast cancer may be associated with the combined hormone replacement therapy, or that which includes estrogen and progestin.

Research appearing in the Dec. 15 issue of the journal Cancer finds that women on combined hormone therapy are at an increased risk for lobular breast cancer.

Lobular and ductal breast cancer are two of the more common forms of breast cancer. Although lobular carcinoma is less aggressive than ductal, it has been on the rise since the 1980s. The use of combined hormone replacement therapy increased during the same time period, leading some to speculate that it might be responsible for the increase.

"It's kind of a bad news/good news thing," says Janet Daling, lead author of the study and a professor of epidemiology at Fred Hutchinson Cancer Research Center in Seattle. "[Lobular carcinoma] is a little more difficult to diagnose because you don't pick it up as often on mammograms, but it has a good prognosis. It appears to be highly related to the continuous combined hormone therapy."

Hormone replacement therapy (HRT) is taken by women to relieve symptoms of menopause. While the hormone estrogen is actually responsible for reducing hot flashes and vaginal dryness, it also increases the risk of cancer of the uterine lining. Adding progestin to the mix effectively eliminates that risk.

This study, called the Women's Contraceptive and Reproductive Experiences (CARE) Study, looked at approximately 4,500 postmenopausal women aged 35 to 64 who had been diagnosed with their first incidence of breast cancer. They were compared to a control group of postmenopausal women who had no history of breast cancer.

In interviews, all of the women were asked to recall information on various aspects of their medical history, including type of hormone therapy used, pattern of use, dose, and total duration.

Women who used combined hormone replacement therapy for six months to five years were 1.6 times more likely to get lobular carcinoma. Women who used it for more than five years were twice as likely to be diagnosed with the cancer, compared with women who never used it.

The risk was also greater with continuous hormone therapy, or that which is delivered daily for 25 or more days each month. Women on this type of hormone replacement therapy for five years or more had a 2.5 times greater risk of lobular breast cancer. After adjusting for the age at which menopause began, the increase rose to 3.2 times.

Sequential combined hormone replacement therapy was associated with a 1.5 times greater risk for lobular cancer. "There was very little risk with sequential HRT," Daling says.

A Word of Caution

Dr. Clifford Hudis, chief of the breast cancer medicine service at Memorial Sloan-Kettering Cancer Center in New York City, cautions against giving too much weight to the findings. This latest research was a case-control study in which women were asked to remember details of their history, and there was no actual control over the dispensing of the medication. The gold standard in medical research remains the prospective randomized trial. "This is the highest standard because presumably bias doesn't influence who takes or doesn't take the medicine," Hudis says.

The results of this study apply only to women under the age of 65. Daling has just finished another study looking at women aged 65 to 79 and, in this group, sequential HRT seemed to play a larger role.

Estrogen alone did not appear to affect the risk of breast cancer.

Always consult your physician for more information.