A new study published in the Lancet medical journal shows a significant decline in the number of deaths from brea Tamoxifen Responsible for Decline in Breast Cancer Deaths (dateline May 19, 2000) | Breast Health News | Imaginis - The Women's Health & Wellness Resource Network

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Tamoxifen Responsible for Decline in Breast Cancer Deaths (dateline May 19, 2000)

A new study published in the Lancet medical journal shows a significant decline in the number of deaths from breast cancer in Britain and the United States. While a number of factors contribute to the decline, researchers believe the increased use of the drug tamoxifen (brand name, Nolvadex) plays a large role. Other therapies such as chemotherapy and radiation therapy have also helped slow the rate of breast cancer deaths.

According to Richard Peto, a professor of epidemiology at Oxford University in Britain, deaths from breast cancer have declined by 25% in the United States since the late 1980s. In 2000, it is estimated that around 40,000 American women will die from breast cancer. If tamoxifen and chemotherapy were not widely used today, an estimated 50,000 women would die from breast cancer.

In Britain, the decline in deaths from breast cancer is even greater. Approximately 30% fewer women will die of breast cancer in Britain this year: 13,000 women compared with approximately 17,000 women who died annually from breast cancer in the late 1980s. Researchers attribute the sharper decline in breast cancer deaths in Britain to the fact that tamoxifen was originally developed in Britain and has been used there for a longer period of time than in the United States.

Tamoxifen is the most commonly prescribed drug used to treat breast cancer. In 1998, tamoxifen was also approved by the U.S. Food and Drug Administration (FDA) to help prevent breast cancer in women at high risk of the disease. According to the researchers, tamoxifen alone has been found to eliminate one in six breast cancer recurrences and reduce the chances that breast cancer will return in the opposite breast by 50%.

The risks of taking tamoxifen can be severe. Tamoxifen increases the chances for 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), and possibly stroke. Yet the study found that the benefits of taking tamoxifen for five years greatly outweighed the risks in the majority of cases.

According to the study, for every 1,000 women who take tamoxifen, 80 fewer deaths from breast cancer will occur. Two additional deaths will occur from endometrial cancer among every 1,000 women on tamoxifen and one more death will occur from pulmonary embolism.

Tamoxifen is an "anti-estrogen" and works by competing with estrogen to bind to estrogen receptors in breast cancer cells. By blocking estrogen in the breast, tamoxifen helps slow the growth and reproduction of breast cancer cells. Tamoxifen was first used in Britain in 1973 and approved by the FDA for use in the United States five years later.

Benefits from Chemotherapy and Radiation Therapy

In addition to the increased use of tamoxifen, researchers also attribute the decline in breast cancer deaths to chemotherapy.   Chemotherapy seems to be particularly useful in young women with breast cancer, according to the researchers. However, only around one-third of middle-aged women benefit as much from chemotherapy as tamoxifen. Chemotherapy is treatment with a combination of anti-cancer drugs.

Radiation therapy has also helped reduce breast cancer deaths. According to the study, approximately two-thirds of breast cancer recurrences can be prevented with radiation therapy. Radiation therapy has reduced deaths from breast cancer by 5% since the late 1980s but has increased the rate of death from other causes by 4%.

Radiation therapy can increase the risk of heart attack and stroke.  Another recent study published in the Lancet medical journal shows that younger women (age 50 or younger) are less likely to die from heart-related problems within 10 years of radiation therapy than women in their sixties. However, this study included women who had radiation therapy in the 1960s, 1970s, and 1980s, when older breast radiation techniques exposed the neck and chest to radiation beams.

Regardless of the risks associated with breast cancer therapies, the decline in breast cancer deaths from improved treatment is greater than among other common cancers (such as skin or lung cancers). Researchers expect that an analysis of other Western countries would show a similar decline in deaths.

Approximately two-thirds of breast cancer deaths have been prevented among women between 20 and 69 years of age, according to the study. The widespread increase in breast cancer screening with mammography has not been practiced long enough to have an impact on the number of deaths from breast cancer.