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Tamoxifen and Raloxifene to Reduce Breast Cancer Risk
Several clinical studies have shown that in women known to be at increased risk for breast cancer, tamoxifen, and possibly raloxifene, may reduce this risk. However, tamoxifen and raloxifene are not without possible side effects, and they may not be right for all women who are at increased risk for breast cancer.

The following information is intended to help you understand what is known - and what is not known - about tamoxifen and raloxifene and their ability to reduce breast cancer risk, as well as their possible side effects. You and your doctor can use this information to help you decide whether or not one of these medicines may be right for you.

What Is Tamoxifen?

Tamoxifen is a drug, taken daily as a pill. It has been used for more than 25 years to treat patients with breast cancer. Tamoxifen works against breast cancer, in part, by interfering with the activity of estrogen, a female hormone that can promote the growth of breast cancer cells. For this reason, tamoxifen is often called an "anti-estrogen."

As a treatment for breast cancer, the drug slows or stops the growth of cancer cells that are already present in the body. Tamoxifen also helps to prevent new cancers from developing in women who have been treated for breast cancer. Several studies have now looked at tamoxifen’s ability to reduce the chance of developing breast cancer in women known to be at increased risk for the disease.

How Effective Is Tamoxifen in Reducing the Risk of Developing Breast Cancer?

The largest study to look at tamoxifen for preventing breast cancer, the Breast Cancer Prevention Trial (BCPT), was sponsored by the National Cancer Institute (NCI). In the study, more than 13,000 women at higher than average risk of breast cancer were assigned to take a pill each day for almost 5 years. The pill contained either tamoxifen or a placebo (inactive ingredient), but the women didn't know which pill they were taking. The study found that compared to the women on placebo, those who took tamoxifen had:

  • About half the risk of invasive breast cancer. There were 89 cases in the tamoxifen group vs. 175 cases in the placebo group.

  • About half the risk of noninvasive breast cancer, such as ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS). There were 35 cases in the tamoxifen group vs. 69 cases in the placebo group.

For those who developed breast cancer, there was no difference in survival after about 5 years between the group that took tamoxifen and the group that did not.

Some smaller studies, however, have not found such a strong protective benefit for tamoxifen. Two studies (conducted in Italy and in England) that looked at women of slightly different ages and with different risk factors from the NCI study did not find that tamoxifen significantly reduced the risk of breast cancer.

The most recent study to look at tamoxifen for breast cancer risk reduction, the IBIS-I study, was an international clinical trial that involved more than 7,000 women at increased risk. The study was similar in design to the BCPT study. After an average of about 4 years, the group taking tamoxifen had about one-third (32%) fewer cases of breast cancer compared to those taking a placebo. These results are still early, however, as about half of the women have not yet taken the pills for 5 years.

Are There Other Benefits of Taking Tamoxifen?

Tamoxifen may slightly reduce the risk of bone fractures of the hip, wrist, and spine in women who are past menopause. It did not protect against heart attacks in the BCPT study.

Are There Risks with Taking Tamoxifen?

Tamoxifen is a complex chemical. In addition to its properties as an "anti-estrogen," it appears to have some weak estrogen-like properties as well. Because of this, tamoxifen increases a woman's chance of some rare but serious health problems:

  • endometrial cancer (cancer of the lining of the uterus)
  • uterine sarcoma (cancer of the connective tissue of the uterus)
  • pulmonary embolism (a blood clot in the lung)
  • deep vein thrombosis (a blood clot in a major vein).

Endometrial cancer and uterine sarcoma: Estrogens and agents that act like estrogens are known to increase the risk of endometrial cancer. According to the BCPT study, tamoxifen increases a woman's chance of developing endometrial cancer (based on 53 cases in the tamoxifen group vs. 17 cases in the placebo group of the study). It also appears to increase the risk of developing a rare but serious form of cancer known as uterine sarcoma (based on 4 cases in the tamoxifen group vs. 0 cases in the placebo group).

It is especially important for doctors to discuss this information with women who have taken or are taking tamoxifen and strongly encourage these women to report any unexpected vaginal bleeding or spotting, which could be symptoms of these cancers. Doctors should also tell women taking tamoxifen about the potential benefits, risks, and limitations of testing for early endometrial cancer detection.

Endometrial cancer usually can be found at an early stage, when treatment is very effective. Women who have had a hysterectomy (surgery to remove the uterus) are not at any known risk for endometrial cancer. The 2 main methods currently available for detecting endometrial cancer are the endometrial biopsy and transvaginal ultrasound. For an endometrial biopsy, a small sample of endometrial tissue is obtained by applying suction to a very thin flexible tube inserted into the uterus through the cervix. A transvaginal ultrasound (sonogram) uses sound waves to create images of the uterus. A probe inserted into the vagina releases sound waves that echo off tissue of the pelvic organs. A computer translates these echo patterns into an image of the uterus.

Although the American Cancer Society recommends that women taking tamoxifen learn about their options for endometrial cancer screening so that they can make informed decisions, ACS makes no recommendation for routine screening for these women because studies have not found such screening to help find endometrial cancer at a more curable stage. And, many studies have found that routine screening for endometrial cancer causes unnecessary surgery to evaluate "false positive" test results.

Blood clots: According to the BCPT study, women taking tamoxifen have 3 times the chance of developing a pulmonary embolism, or blood clot in the lung (based on 18 cases in the tamoxifen group vs. 6 cases in the placebo group of the study). Women in the tamoxifen group were also more likely to have deep vein thrombosis (a blood clot in a major vein) than women on placebo (35 cases vs. 22 cases).

The IBIS-I study also found an increased risk of blood clots (about 2.5 times higher) in the women who took tamoxifen, especially among those who had recently had major surgery. Women on tamoxifen who will be undergoing surgery may want to speak with their doctors about this.

In general, blood clots occur more often in people with high blood pressure (hypertension) or diabetes, smokers, and in those who are obese.

Are There Any Other Side Effects of Tamoxifen?

Like most medications, whether over-the-counter medications, prescription drugs, or drugs in research studies, tamoxifen causes side effects in some women. The effects experienced most often by women in the BCPT study were hot flashes and vaginal discharge.

Other side effects were also reported, but these were no more common in the women who took tamoxifen than in the women who took placebo:

  • vaginal dryness, itching, or bleeding
  • menstrual irregularities
  • depression
  • loss of appetite
  • nausea and/or vomiting
  • dizziness
  • headaches
  • weight gain
  • fatigue

Treatments that could reduce or eliminate most of these side effects are available.

Some research has shown that women who took tamoxifen were at a slightly increased risk for developing cataracts (a clouding of the lens inside the eye). Over the course of the BCPT study, 574 women in the tamoxifen group and 507 women in the placebo group developed cataracts; 114 and 73 women, respectively, had cataract surgery. The IBIS-I study, however, did not find an increased risk of cataracts. As women age, they are more likely to develop cataracts whether they take tamoxifen or not.

As in the BCPT study, women on tamoxifen in the IBIS-I study were also more likely to experience vaginal discharge and hot flashes. New findings in the IBIS-I study included an increased risk of vaginal yeast infections and an increased risk of having brittle nails.

Does Tamoxifen Cause a Woman to Begin Menopause?

Tamoxifen does not cause a woman to begin menopause, although it can cause some symptoms (such as hot flashes, night sweats, mood swings, and vaginal dryness) that are similar to those that may occur during menopause. In most premenopausal women taking tamoxifen, the ovaries continue to act normally and produce female hormones (estrogens) in the same or slightly increased amounts.

How Long Should Women Take Tamoxifen?

When used to treat breast cancer, tamoxifen should be taken for 5 years. In one study, women with early stage breast cancer who took tamoxifen for 10 years had no greater benefit from the longer duration of tamoxifen and showed a trend toward more adverse effects.

In the BCPT study, women took tamoxifen for 4 to 5 years. The ideal length of time women should take tamoxifen to reduce their risk of breast cancer is not known. Based on the best information available at this time, women should take the drug for 5 years.

Does Tamoxifen Have the Same Risks as Hormone Replacement Therapy?

Hormone replacement therapy (HRT) is used by some women to reduce hot flashes and other problems after menopause that can affect quality of life. It may also help women maintain bone density, reducing the risk of fractures, and may reduce the risk of colon cancer.

But studies have suggested that combined hormone replacement therapy (estrogen plus progesterone)increases a woman's chances of developing heart problems, blood clots, breast cancer, and other serious health problems. Women considering using HRT after menopause should be aware of these potential effects and should discuss this thoroughly with their doctor before deciding on a course of action. Those who decide to use HRT should do so at the lowest effective dose and for the shortest possible time.

Tamoxifen, on the other hand, does not reduce menopausal symptoms and may actually make them worse. Like hormone replacement therapy, it appears to increase the risk of blood clots. It does, however, reduce breast cancer risk and may help slow or reduce bone loss.

Who Should Consider Taking Tamoxifen to Reduce Their Breast Cancer Risk?

The BCPT study looked only at women who were at increased risk for developing breast cancer. These included:

  • Women 60 years of age and older, and
  • Women between the ages of 35 and 59 with risk factors that increased their chances of developing breast cancer within the next 5 years to the same level or higher than that of a 60-year-old woman

This risk is about 1.7%, meaning that at age 60, about 17 of every 1,000 women are expected to develop breast cancer within 5 years.

Many diseases, including breast cancer, heart disease, and osteoporosis, occur more often in older women. The risk of developing breast cancer increases with age, so breast cancer occurs more commonly in women over 60 years old compared to women in their 40s and 50s. A woman younger than age 60 could have similar risk to a 60 year-old woman (or even higher) if one or a combination of the following factors is present:

  • Having a BRCA1 or BRCA2 gene alteration
  • Previous history of breast cancer
  • Breast biopsy that shows either a condition called atypical ductal hyperplasia (ADH) or lobular carcinoma in situ (LCIS), a condition that is not cancer but indicates an increased chance of developing invasive breast cancer
  • Family history of breast cancer (i.e. several close relatives -- mother, sister(s), daughter(s) -- particularly if they were diagnosed before menopause)
  • Not having any children, or having a first child later in life
  • Starting menstrual periods before age 12 or going through menopause after age 55

To learn more about your own breast cancer risk and whether you might want to consider taking tamoxifen, see the "Breast Cancer Risk Assessment: Should I Consider Taking Tamoxifen?" below.

Should Certain Women NOT Take Tamoxifen for Risk Reduction?

Tamoxifen should not be used to reduce breast cancer risk in women who:

  • Have ever had blood clots or who develop blood clots that require medical treatment.
  • Are taking medicines to thin their blood.
  • Have a history of high blood pressure, smoking, obesity, or diabetes. Tamoxifen increases the risk of blood clots in these women.
  • Are planning to become pregnant or are pregnant.
  • Are breast-feeding.
  • Are less than 35 years old, or are less than 60 years old who are not at increased risk.
  • Have not had any type of assessment of their risk of developing breast cancer.
  • Are currently taking hormone replacement therapy or raloxifene.

There may be other reasons that a woman should not take tamoxifen, such as atypical hyperplasia of the uterus or cataracts. Women should talk with their doctor about their specific situation.

This drug may cause birth defects if taken at the time of conception or during pregnancy and may affect fertility. People taking this drug need to use a barrier or nonhormone method of birth control. Therefore, if you are pregnant, breast-feeding, or planning to have children in the future, tell your doctor before your treatment starts. Do not use oral contraceptives (birth control pills) or other contraceptives with hormones while taking this drug before checking with your doctor.

Should Women Who Are at Increased Risk of Breast Cancer Take Tamoxifen?

Women who are at increased risk of breast cancer now have the option to consider taking tamoxifen to reduce their chances of developing breast cancer. As with any medical procedure or treatment, the decision to take tamoxifen is an individual one in which the benefits and risks of the therapy must be considered.

The balance of these benefits and risks will vary depending on a woman's personal health history and how she weighs the benefits and risks. Therefore even if a woman is at increased risk of breast cancer, tamoxifen therapy may not be appropriate for her. Women who are considering tamoxifen therapy should talk with their doctor about their circumstances in order to make a decision that is best for them.

Should Women Who Are NOT at Increased Risk of Breast Cancer Take Tamoxifen?

Because tamoxifen has never been studied in healthy women at average risk for breast cancer, there's no way to know if it would decrease their breast cancer risk and if so, by how much. Only higher risk women were allowed to participate in the BCPT prevention study, in part because there are known side effects of taking tamoxifen.

Women at average risk would be exposed to the same risks of the drug, but the benefit would be less because fewer women would be expected to develop breast cancer than women at higher risk. Women who are not at increased risk should talk with their doctor about their specific situation.

Breast Cancer Risk Assessment: Should I Consider Taking Tamoxifen?

There is no easy answer to this question, and ultimately any decision you make should be made with your doctor. As is the case with almost all drugs, there are benefits and risks associated with taking tamoxifen.

For now, experts feel that a woman's breast cancer risk should be higher than the risk faced by an average woman for her to consider taking tamoxifen. A woman who is at higher than average risk needs to consider the benefit of possibly reducing her breast cancer risk with the potential for side effects and complications from taking tamoxifen.

To find out if you are at higher than average risk for breast cancer, your risk factors need to be identified. A risk factor is anything that affects a person's chance of getting a disease. For example, smoking is a risk factor for lung and several other cancers.

As you may know, age is the major risk factor for breast cancer. The risk increases as you get older. If you are 60 years old, you have a higher risk of having breast cancer than if you are 40. Another risk factor is family history. If your mother or sister has had breast cancer then you have a higher risk than if you don't have any close relatives with breast cancer. There are other risk factors for breast cancer that are less important, but that in combination can influence your risk, such as age at first menstruation and menopause and your age at the birth of your first child.

Higher risk based on a particular characteristic or risk factor simply means that you are at higher risk for breast cancer compared with someone who doesn't have that risk factor. But being at higher risk does not mean that you will develop breast cancer; in fact, most women with one or more risk factors will never develop breast cancer.

To get some idea about your risk of breast cancer (and whether tamoxifen might be an option for you), answer the following questions, which were the ones that doctors asked women who were interested in participating in the BCPT study. The questions are specific to age, personal history of breast cancer, LCIS (lobular carcinoma in situ), DCIS (ductal carcinoma in situ), ADH (atypical ductal hyperplasia), reproductive history, and family history.

QUESTION: How old are you?

If younger than 35 years of age: Tamoxifen is not approved for use in women younger than age 35.

If 35-55 years of age:Go to the next question.

If in your late 50s: When the BCPT study was set up, it was decided that all women 60 and older automatically qualified to participate. This is because breast cancer risk increases with age. The study showed that tamoxifen appeared to reduce breast cancer risk by about half for women age 60 and older.

Choosing an age cutoff of 60 was somewhat arbitrary for the purpose of the scientific study. Women in their late 50s are at similar risk to women in their early 60s--the age cutoff could have just as easily been 59 or 62. Also, some women in their 50s have a higher risk than some women in their 60s because there are other factors besides age that affect risk, such as the age at which a woman had her first child. (For more information, refer to the American Cancer Society document, "Breast Cancer".)

Tamoxifen is approved for all women over the age of 60, but we don't know how effective tamoxifen would be for women in their 50s who don't have a lot of other risk factors, as those women did not participate in the study. But because you are close to the age cutoff, it may be OK for you to consider taking tamoxifen. Please discuss this with your doctor, and discuss in particular the risks and benefits of taking tamoxifen and your personal risks for blood clots and osteoporosis, as well as breast cancer and endometrial cancer.

If 60 or older: Doctors consider an average woman's risk at age 60 to be sufficient to consider taking tamoxifen to reduce breast cancer risk, so this is an option for you. When the study of tamoxifen was set up, it was decided that all women 60 and older (regardless of any other risk factor) automatically qualified to participate because breast cancer risk increases with age. Tamoxifen was shown to reduce breast cancer risk by about half for women age 60 and older, like you.

QUESTION: Have you ever had breast cancer, lobular carcinoma in situ (LCIS), or atypical ductal hyperplasia (ADH)?

If you had breast cancer (including DCIS):

QUESTION: ...did you take tamoxifen as part of your treatment?

If yes: Tamoxifen should only be taken for 5 years, so you would not be an appropriate candidate for taking tamoxifen to further reduce your risk.

If no: The tamoxifen study did not include women who had breast cancer (or DCIS) previously. Talk to your doctor about whether taking tamoxifen for risk reduction is an option for you now.

If you had LCIS and are 35 or older: Doctors consider the breast cancer risk of women who have had LCIS to be sufficient to consider taking tamoxifen to reduce breast cancer risk, so this is an option for you. When the BCPT study was set up, it was decided that any woman with LCIS automatically qualified to participate because LCIS is a risk factor for breast cancer.

If you had ADH and are 35 or older: ADH by itself may not increase a woman's risk of getting breast cancer to the level where she might consider taking tamoxifen. However, women who have had a diagnosis of ADH and who also have other risk factors may have a higher than average risk that is sufficient to consider taking tamoxifen. Talk to your doctor about all of your risk factors and how they affect your individual risk, so you can make an informed decision about whether or not to take tamoxifen.

QUESTION: Do you have a family history of breast cancer?

If no: Proceed to the next question.

If yes and you are age 35 or older: When the BCPT study was set up, it was decided that any woman age 35 and older with at least 3 close relatives who have had breast cancer automatically qualified to participate because a strong family history is a risk factor for breast cancer. A close relative was defined as a mother, sister, or daughter for the purposes of that study.

If you have grandmothers, aunts, and/or first cousins who are all related (for example, all on one side of the family and related by blood rather than marriage) and who were diagnosed with breast cancer prior to age 50 and/or ovarian cancer at any age, you may want to talk to your doctor about your risk and whether to consider taking tamoxifen.

If you are "positive for the breast cancer gene" or have been told that you have a mutation (change) in one of the breast cancer genes (BRCA1 or BRCA2): Doctors consider the breast cancer risk of women who have had a genetic test result that shows a mutation (change) in the BRCA1 or BRCA2 gene to be sufficient to consider taking tamoxifen to reduce breast cancer risk, if you are age 35 or older, so this is an option for you.

As part of the follow-up to the BCPT study, the researchers looked specifically at the effect of tamoxifen in women in the study with BRCA1 or BRCA2 mutations. They found that tamoxifen seemed to reduce breast cancer risk among BRCA2 carriers (by about 60%) but not among women with BRCA1 mutations. The number of women in both groups was small, however, so the true impact of tamoxifen among women with these mutations is not well understood.

QUESTION: Do you have other breast cancer risk factors?

Other factors known to increase your risk of breast cancer include:

  • Start of menstrual periods at an early age (before age 12)
  • Having no children, or having your first child later in life
  • Going through menopause after age 55

If no: Most women under age 55 who do not have a strong family history of breast cancer, a personal history of breast cancer, or other factors are not at high enough risk to consider taking tamoxifen based on the information available today.

If yes: A small percentage of women under age 55 who do not have a personal or family history of breast cancer may have a combination of risk factors that would put them in a higher risk category. If you think this might be true for you, then talk to your doctor and ask him or her to estimate your risk of getting breast cancer.

Breast Cancer Risk Assessment Tools

Researchers have developed several different statistical models to predict a woman’s risk of developing breast cancer.

The "Risk Disk" is a tool designed for health professionals based on the questions above. It allows doctors and nurses to help women make informed decisions about taking tamoxifen. It uses specific calculations to find out a woman’s risk of developing breast cancer in the next 5 years and over her lifetime, based on certain risk factors.

The tool does have limitations, however. Some doctors feel it does not count family history strongly enough, for example. It’s also important to note that this tool was developed specifically for health professionals, so it may contain terms and explanations that are unfamiliar to you. Ask your doctor about using this tool to give you a better idea about your risks and whether you should consider taking tamoxifen.

Other risk tools based on slightly different criteria, such as the BRCAPRO and the Claus models, can also be used to estimate risk.

None of these models is perfect. Each has its strengths and weaknesses, and a woman’s risk may vary depending on the model used. Many models have not been tested on minority groups to ensure they apply equally to all women. These tools can only provide a rough estimate of risk, but they can’t tell for certain whether you will develop breast cancer.

Eligibility for Tamoxifen vs. Benefit from Tamoxifen

Based largely on the results of the BCPT study, the US Food and Drug Administration (FDA) approved tamoxifen for reducing the risk of breast cancer in women whose risk of developing the disease was at least 1.67% within the next 5 years. This included all women over the age of 60, as well as those between 35 and 59 with factors that increased their risk to this level, as described above.

But not everyone who is eligible for tamoxifen would necessarily benefit from taking it, as there are potentially serious side effects. Since the BCPT study, researchers have attempted to look at more than just a woman’s risk of developing breast cancer in trying to determine whether she might benefit.

For example, older women are at higher risk of breast cancer than are younger women, which could mean tamoxifen might be more likely to reduce this particular risk. But older women are also more likely to experience a stroke or a blood clot, which could mean tamoxifen might be riskier for them.

Recent studies estimate that about 15% of all women over the age of 35 would be eligible to take tamoxifen to reduce their risk of breast cancer, according to the criteria used by the FDA. But only in about 1/3 of these women would the benefit clearly outweigh the risk. Generally speaking, younger women at high risk appear to have a better benefit-to-risk ratio from tamoxifen than do older women. But it’s important to remember that each woman is unique, and the possible benefits and risks for her depend on many factors.

Tamoxifen to Reduce Breast Cancer Risk: Conclusions

Scientists are working very hard to develop information about competing risks, such as how a woman's risk of heart disease should influence her decisions about breast cancer risk reduction. As new information is collected, recommendations about who should and who should not consider taking tamoxifen may change. Also remember that your risk changes over time... with age, a new diagnosis of breast cancer in your family, or if you have a biopsy, for example.

Some experts think that more research is needed to determine the benefits and risks of taking tamoxifen for breast cancer risk reduction. The BCPT study showed the risk of breast cancer development was reduced by half, but after 5 years of research time there was no effect on deaths due to breast cancer. Other, smaller studies have not found as strong a benefit for tamoxifen. More research is needed to answer the many questions about tamoxifen and breast cancer.

What Is Raloxifene?

Raloxifene is a drug that is similar in many ways to tamoxifen. Both of these compounds can help prevent osteoporosis, or weakening of the bones, that can occur in women after they reach menopause. Raloxifene is approved by the FDA for this use.

Early results from a study of osteoporosis in women who had already gone through menopause and took either raloxifene or a placebo (the Multiple Outcomes of Raloxifene Evaluation, or MORE trial) suggested that raloxifene may also reduce breast cancer risk. Although the study was designed to look at osteoporosis, after several years researchers observed a significant reduction in the number of breast cancers in those women taking the drug compared to those taking the placebo.

What Are the Benefits and Risks of Taking Raloxifene?

Information about raloxifene is limited compared with that on tamoxifen because it has been studied for a shorter time and in a smaller number of women.

In the MORE trial, which included over 7,000 postmenopausal women, the group taking raloxifene had about 60% to 70% fewer breast cancers over the next 8 years compared with the women taking the placebo.

Raloxifene was also found to increase the density of bones and to reduce the risk of certain types of bone fractures.

Overall, raloxifene did not have an effect on the risk of heart attacks or strokes in the MORE trial, but it did appear to reduce this risk among women who already had risk factors for these problems. Further studies are now underway to try to confirm these results.

A serious risk associated with raloxifene is blood clots in the legs or lungs; the number of blood clots observed in women taking raloxifene was higher than in those taking no drug.

The women taking raloxifene were not at higher risk for endometrial cancer (a serious side effect of tamoxifen), but very few endometrial cancers were observed in either the women taking the drug or those taking the placebo, and not all of the women were examined for this type of cancer.

Other side effects reported more frequently in the women taking raloxifene than those getting a placebo included hot flashes, leg cramps, flu-like symptoms, and edema (swelling in the hands or feet).

Is Raloxifene Available to Use for Reducing Breast Cancer Risk?

Raloxifene (Evista) is currently used to treat osteoporosis. It has not been approved by the FDA for breast cancer risk reduction.

The National Cancer Institute is conducting a large clinical trial called the STAR (Study of Tamoxifen and Raloxifene) trial. The study includes about 22,000 postmenopausal women who are at increased risk of breast cancer, comparing the effectiveness and the risks of raloxifene and tamoxifen. Each woman is taking one or the other daily for 5 years, but does not know which of the 2 she is receiving. While enrollment has been completed, the results of the study are not expected for several years.

A second study, known as Raloxifene Use for the Heart (RUTH), is focusing on raloxifene’s effects on both heart disease and breast cancer. Enrollment of over 10,000 women in this study has been completed, and results are expected within the next few years.

Additional Resources

ACS Publications

Breast Cancer

National Organizations and Web Sites

National Cancer Institute (NCI)
Telephone: 1-800-4-CANCER
Internet Address: www.cancer.gov

References

Barrett-Connor E, Grady D, Sashegyi A, Anderson PW, Cox DA, Hoszowski K, Rautaharju P, Harper KD; MORE Investigators. Raloxifene and cardiovascular events in osteoporotic postmenopausal women: four-year results from the MORE (Multiple Outcomes of Raloxifene Evaluation) randomized trial. JAMA. 2002; 287(7): 847-857.

Cauley JA, Norton L, Lippman ME, Eckert S, Krueger KA, Purdie DW, et al. Continued breast cancer risk reduction in postmenopausal women treated with raloxifene: 4-year results from the MORE trial. Multiple outcomes of raloxifene evaluation. Breast Cancer Res Treat. 2001; 65(2):125-134.

Fisher B, Costantino JP, Wickerham DL, Redmond CK, Kavanah M, et al. Tamoxifen for Prevention of Breast Cancer: Report of the National Surgical Adjuvant Breast and Bowel Project P-1 Study. JNCI. 1998; 90(18): 1371-1388.

Freedman AN, Graubard BI, Rao SR, McCaskill-Stevens W, Ballard-Barbash R, Gail MH. Estimates of the number of U.S. women who could benefit from tamoxifen for breast cancer chemoprevention. JNCI. 2003; 95(7): 526-532.

Gail MH, Constantino JP,Bryant J, Croyle R, Freedman L, Helzlsouer K, Vogel V. Weighing the risks and benefits of tamoxifen treatment for preventing breast cancer. JNCI. 1999; 91(21):1829-1846.

IBIS Investigators. First results from the International Breast cancer Intervention Study (IBIS-I): a randomized prevention trial. Lancet. 2002; 360: 817-824.

King MC, Wieand S, Hale K, Lee M, Walsh T, et al; National Surgical Adjuvant Breast and Bowel Project. Tamoxifen and breast cancer incidence among women with inherited mutations in BRCA1 and BRCA2: National Surgical Adjuvant Breast and Bowel Project (NSABP-P1) Breast Cancer Prevention Trial. JAMA. 2001 Nov 14; 286(18): 2251-2256.

Kinsinger LS, Harris R, Woolf SH, Sox HC, Lohr KN. Chemoprevention of breast cancer: a summary of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2002; 137:59-67.

Martino S, Cauley JA, Barrett-Connor E, Powles TJ, et al. Incidence of invasive breast cancer following 8 years of raloxifene therapy in postmenopausal women with osteoporosis: Results from the Continuing Outcomes Relevant to Evista (CORE) trial. J Clin Onc. 2004 ASCO Annual Meeting Proceedings (Post-Meeting Edition). Vol 22, No 14S (July 15 Supplement), 2004: 1000.

Powles T, Eeles R, Ashley S, Easton D, Chang J, Dowsett M, et al. Interim analysis of the incidence of breast cancer in the Royal Marsden Hospital tamoxifen randomized chemoprevention trial. Lancet. 1998; 352: 98-101.

US Preventive Services Task Force. Chemoprevention of breast cancer: recommendations and rationale. Ann Intern Med. 2002; 137:56-58.

Veronesi U, Maisonneuve P, Sacchini V, Rotmensz N, Boyle P. Tamoxifen for breast cancer among hysterectomised women. Lancet. 2002; 359: 1122-1124.

Revised 10/06/04

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