Spokane-area doctors say they think a commonly prescribed osteoporosis medication approved by the U.S. Food & Drug Administration last fall for use in preventing breast cancer is a welcome addition to the drug arsenal and could help boost awareness about prevention options.


The drug, raloxifene, sold under the brand name Evista, now is being marketed for that purpose, in addition to its osteoporosis-related benefits, and study results are encouraging.


Though a similar drug aimed at preventing breast cancer has been in use for years, cancer specialists here say general practitioners might be more comfortable prescribing Evista because they already are familiar with it.


Results from studies involving about 37,000 participants helped qualify the long-time osteoporosis treatment for use in breast-cancer prevention. Those studies indicate that treatment with Evista or another drug, tamoxifen, can reduce the risk of getting breast cancer by up to 50 percent for postmenopausal women who are considered at high-risk to develop the disease, says Fred Viren, a retired internist here who gives seminars on the drug. Viren says the benefit to patients with osteoporosis is even greatera 70 percent breast cancer risk reduction.


The most recent study, funded primarily by the National Cancer Institute, was called the Study of Tamoxifen and Raloxifene (STAR) and compared the relative results and side effects of the two drugs over a five-year period, using data from about 19,000 participants across the U.S.


Tamoxifen and raloxifene are similar drugs in the family called selective estrogen receptor modulators (SERMs). Tamoxifen has been used for years to treat invasive breast cancer and to prevent recurrences.


The STAR study included women who were considered at high risk for developing breast cancer, based on an assessment system called the Gail model.


The Gail model computes a score based on various risk factors such as early menstrual cycles, late childbearing, and family history of breast cancer, Viren says. A Gail model score of 1.66 or higher is considered high risk, and more than half of all women over age 60 have a Gail score of more than 2.0, he says.


The majority of breast cancers are of the estrogen receptor type, which means they are fed by estrogen, Viren says. Raloxifene, which has been used for years to treat osteoporosis in postmenopausal women, is shown to prevent that type of cancer by blocking the estrogen receptors that bind to estrogen, which can fuel the growth of abnormal breast cells, he says.


Though raloxifene and tamoxifen had similar results in the STAR study, there were some differences noted in the study results. Tamoxifen can be used in premenopausal women, while raloxifene hasnt been tested for use by premenopausal women. Both drugs caused an increased incidence of hot flashes and blood clots.


Patients who used tamoxifen sometimes experienced more uterine bleeding and cramping, and patients who used raloxifene sometimes experienced more joint pain.


Jeanne Robison, the clinical director of cancer services for Rockwood Clinics cancer centers here, where she has been operating a high-risk breast cancer center for eight years, says there was little difference between raloxifene and tamoxifen in the study results. In fact, she says, raloxifene appeared to be less effective than tamoxifen for preventing so-called ductal or lobular carcinoma in situ, which are, respectively, cancerous and precancerous conditions that both signal an increased risk of a woman developing invasive breast cancer.


Robison says the results the drugs produced during the five-year study otherwise were similar, and though a slightly lower rate of uterine cancer has been cited in patients who took raloxifene, the difference was too small to be deemed significant. Although the drugs have similar side effects, some of the side effects that have given women pause about taking tamoxifen, such as uterine bleeding and cramping, might be reduced slightly with raloxifene, she says.


Joni Nichols, a medical oncologist at Cancer Care Northwest PS, of Spokane, says one thing raloxifene may have going for it in raising awareness that breast cancer can be prevented is that its perceived differently than tamoxifen. Nichols says doctors sometimes will refer women they consider at high risk for breast cancer to Cancer Care Northwest for evaluation and prescription of tamoxifen, because they arent as comfortable prescribing what they consider a cancer drug themselves, though tamoxifen also has been shown to be useful in preventing fractures.


She says one of the main advantages that Evista could have is that physicians already are familiar with it and prescribe it for osteoporosis patients. She says those doctors might consider it more readily for high-risk breast cancer patients who also have bone-density issues.


Primary-care providers have to buy into that, she says, in order for its use to become more widespread.


Viren says women with osteoporosis are at an increased risk for breast cancer, making use of either of the SERMs a good choice for many.


Lee Lang, a spokesperson for drug manufacturer Eli Lilly & Co., the large Indianapolis-based pharmaceutical company that produces Evista, says the company is developing next-generation SERMs now, including a drug with a working name of arzoxifene, although how those drugs might differ from raloxifene or tamoxifen isnt clear yet.


Nichols says that although Evista is similar to tamoxifen, its good to have multiple drugs available for specified uses.


She says it helps to be able to compare side effects caused by different medications to find the best possible fit for a woman, given her medical history and factors such as whether she has hot flashes that might be worsened by the drugs.


Thats a quality-of-life discussion, Nichols says.


She says another class of breast-cancer prevention drugs that also are in use, called aromatase inhibitors, work by blocking estrogen production altogether, and add another set of chemoprevention options depending on a womans medical history and possible side effects.


Viren, who says education is a key missing component so far in increasing the use of such breast cancer prevention therapies, has contracted with Eli Lilly to give seminars on Evista to physicians.


Lang says the company is considering launching a direct patient marketing program for Evista, much like other pharmaceutical companies have done for their products, though plans have not been finalized.


Viren believes theres a pervasive lack of emphasis on prevention of breast cancer, and says that also is a shortcoming throughout the health-care industry for a host of preventable diseases, such as diabetes.


Nichols says she thinks increasing the options for women at increased risk for breast cancer is a positive step.


We have more choices, Nichols says. Anything we can do to reduce the risk of breast cancer is worthwhile.


Contact Jeanne Gustafson at (509) 344-1264 or via e-mail at jeanneg@spokanejournal.com.