The drug tamoxifen (brand name, Nolvadex) is used to treat both early and advanced stages of breast cancer and prevent breast cancer in women at high risk of the disease. Now, a small study shows that tamoxifen may also help protect the heart by lowering cholesterol and certain protein levels that are associated with heart disease. Though the researchers say that women should not begin taking tamoxifen to protect the heart, the study reveals a possible added benefit of tamoxifen.
In the study, Dr. Mary Cushman of the University of Vermont and her colleagues followed 111 healthy women who were participating in a breast cancer prevention trial. Their findings show that the women who took tamoxifen for six months experienced reductions in cholesterol levels and two proteins that have been linked to heart disease, the C-reactive protein and fibrinogen. However, the women who took a placebo (inactive pill) showed a small increase in fibrinogen and steady levels of the C-reactive protein. No effects were noted on the level of triglycerides (a type of fat) or other blood-clotting proteins. Based on the results of their study, the researchers conclude, "the potential for beneficial cardiovascular effects of tamoxifen in healthy women is suggested."
Fibronogen is a blood-clotting protein that has been linked to an increased risk of heart disease, and the C-reactive protein is an inflammatory marker that may indicate coronary artery disease. Both of these proteins have been linked to heart disease in previous research, although further studies are necessary to prove their roles. High cholesterol is also associated with a high risk of heart disease.
In January 2001, the University of Pittsburgh Medical Center’s the National Surgical Breast and Bowel Project (NSABP) reported their results of a large study (13,000+ women) which revealed that tamoxifen did not increase the risk of cardiovascular problems such as heart attack in healthy women or in women with coronary artery disease. "These findings should provide a degree of comfort to those women who are taking tamoxifen for breast cancer prevention," said Steven Reis, MD, associate professor of medicine at the University of Pittsburgh School of Medicine and lead investigator of the study, in a University of Pittsburgh Medical Center news release.
In the NSABP’s Breast Cancer Prevention Trial, which ran from 1992 to 1998, researchers found that tamoxifen reduced the chances of developing breast cancer in women at high risk by 49%. Most women who take tamoxifen to help prevent breast cancer find that the benefit of reducing their breast cancer risk outweighs the risk of potential side effects of tamoxifen. However, all women who are considering tamoxifen should carefully discuss the advantages and disadvantages of the drug with their physicians.
Possible serious side effects of tamoxifen:
- endometrial cancer (cancer of the lining of the uterus)
- deep vein thrombosis (blood clots in large veins, particularly in the legs)
- pulmonary embolism (blood clot in the lung)
- stroke
While the risks of these side effects is small, they should be taken into account before tamoxifen is prescribed. (See the Coping with Side Effects of Tamoxifen article for more information). In addition, tamoxifen may cause other bothersome side effects, most commonly hot flashes. Tamoxifen is usually prescribed for a period up to five years to help prevent breast cancer.
Women at high risk of breast cancer who may be candidates for tamoxifen include:
- Those with a strong family history breast cancer, especially among several first-degree relatives (mother or sisters)
- Those whose previous breast biopsies show lobular carcinoma in situ (LCIS; also called lobular neoplasia) or atypical hyperplasia
- Those who test positive for the BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) gene mutations
Tamoxifen is not prescribed solely to help protect against heart disease at this time. Further evaluation in large clinical trials is needed to better understand the role tamoxifen may play in protecting the heart.
- The study, "Tamoxifen and Cardiac Risk Factors in Healthy Women: Suggestion of an
Anti-Inflammatory Effect," is published in the February 2001 issue of
Arteriosclerosis, Thrombosis, and Vascular Biology. An abstract of the study is
available online at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?
cmd=Retrieve&db=PubMed&list_uids=11156862&dopt=Abstract - The February 8, 2001 Reuters Health report by Merritt McKinney, "Tamoxifen May Protect Heart," is available within 30 days of publication at http://www.reutershealth.com/archive/2001/02/08/eline/links/20010208elin008.html
- The January 2, 2001 University of Pittsburgh Medical Center news release, "Tamoxifen for Breast Cancer Prevention has no Heart-Related Effects," is available at http://www.upmc.edu/newsbureau/frank/reis_tamoxifen.htm
- The study, "Cardiovascular Effects of Tamoxifen in Women With and Without Heart Disease: Breast Cancer Prevention Trial," is published in the January 3, 2001 issue of the Journal of the National Cancer Institute (Vol. 93, No.1, 16-21). An abstract of the study is available at http://jnci.oupjournals.org/cgi/content/abstract/93/1/16
- The January 3, 2001 Imaginis report, "Study Finds That Tamoxifen Does Not Affect Cardiovascular Health," is available at http://www.imaginis.com/breasthealth/news/news1.03.01.asp
- For general information on tamoxifen, please visit http://www.imaginis.com/breasthealth/tamoxifen.asp
- For information on the side effects of tamoxifen, including statistics on incidence, please visit http://www.imaginis.com/breasthealth/side_effects.asp
- To learn more about heart disease, please visit http://www.imaginis.com/heart-disease/
