(HealthDay)—Women at high risk of breast cancer should discuss with their doctors the use of so-called chemopreventive drugs to reduce that risk, according to a new practice guideline issued by the American Society of Clinical Oncology (ASCO).
The new guideline updates the previous one, issued in 2009, said Dr. Kala Visvanathan, director of the clinical cancer genetics and prevention service at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, who co-chaired the guidelines panel.
"It's a stronger recommendation for discussion of these agents," she said, explaining that the previous guideline suggested the discussion. The new guideline also adds an additional drug option for breast cancer risk reduction.
The guideline was published online July 8 in the Journal of Clinical Oncology.
The key points include a recommendation to discuss the use of tamoxifen (Nolvadex, Tamofen, others) with premenopausal women at high risk, and tamoxifen and raloxifene (Evista) with postmenopausal women. The guideline adds another alternative, exemestane (Aromasin), for postmenopausal women.
Visvanathan and other panel members looked at 19 published articles to assess the risks and benefits of using the drugs to reduce breast cancer risk.
The panel recommended various doses of the drugs, taken daily for five years, to reduce risk. Tamoxifen and raloxifene target estrogen receptors and work to reduce the risk of estrogen receptor-positive, or ER-positive, cancers, which need estrogen to grow.
Exemestane lowers the amount of estrogen in the body. It is not yet approved by the U.S. Food and Drug Administration for breast cancer prevention, but a study has found it can reduce risk by up to 70 percent over three years.
The guideline is meant for women who are cancer-free but at high risk for breast cancer, Visvanathan explained. "We aren't talking about breast cancer survivors and we aren't talking about all women," she said. The guideline only recommends discussing the drugs with a doctor, not that women at high risk should absolutely take them, she added.
Women should talk about the risks and benefits of the drugs to reduce their breast cancer risk and then decide, she said.
Who might fit this profile of high risk? A woman in her 40s who has a condition called atypical hyperplasia, an abnormality in breast cells that has been linked with higher risk of breast cancer, should discuss the use of the drugs, Visvanathan said. So should a woman in her 50s with a family history of breast cancer and who has never given birth.
Women with the BRCA1 and BRCA2 gene mutations, known to boost breast cancer risk, should also discuss the drugs with their doctor, she said, ''although they have other preventive options as well."
More than 2 million U.S. women could benefit from these drugs, according to the researchers. However, few women take the medications.
According to one study published in 2010, only about 1 percent of women, or about 20,000, took tamoxifen as a preventive drug. About four times that number took raloxifene.
For some women, taking the drugs may reduce their risk up to 50 percent, Visvanathan noted.
Side effects, or fear of them, are one reason women decline the drugs, Visvanathan explained. Among the side effects are hot flashes, vaginal dryness and decreased sex drive.
The new, stronger guideline is a good idea, said Dr. Otis Brawley, chief medical officer for the American Cancer Society, who reviewed the guideline but was not involved in writing it.
"We're very supportive of [the recommendations]," he said.
Following the news about actress Angelina Jolie's decision to have a preventive double mastectomy to reduce her higher risk of breast cancer due to a BRCA mutation, Brawley said the new guideline will bring some needed focus to other risk-reduction options.
While Brawley said he supports Jolie's decision, ''there is a group of women at increased risk for whom one of these preventive drugs would be much more appropriate for them and much better for their lifestyle," he explained.
"For some women at increased risk, taking these drugs and closer surveillance could be a better option than bilateral mastectomy," he added.
The drugs, Brawley said, make mammography more effective. "There are studies to show these drugs decrease breast density and therefore increase the ability of mammography [to detect cancer]."
"Ultimately a woman needs to make a decision," he said.
Some members of the panel report consultant work, honoraria, stock ownership or research funding from Novartis, Pfizer, Bayer, Champions Biotechnology or AstraZeneca.
Explore further: UK doctors urged to use preventative breast cancer drugs
To learn more about breast cancer risk, visit the American Cancer Society.