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Tamoxifen Improves Breast Cancer Survival, Decreases Chances of Cancer Returning in Older Women (dateline January 18, 2000)

A recent British study discussed in the medical journal, Cancer, confirms previous data that suggests the benefits of the drug tamoxifen in breast cancer patients may be age-related. In the study, researchers found that breast cancer patients in their 60s with early stage breast cancer had significantly lower cancer recurrence rates and higher survival rates when using tamoxifen than younger women. In other words, after treatment with tamoxifen, older women were more likely to survive breast cancer and not experience any return of the disease than younger women.

The researchers studied 784 women with breast cancer. Among the women whose cancer had not spread to the lymph nodes or any other regions of the body, women between the ages of 60 and 69 had the best responses to treatment with tamoxifen. In the study, 94% of the patients in their 60s and 73% of younger women received tamoxifen. The results showed that over 90% of the women in their 60s survived for three years or more without experiencing a recurrence of breast cancer when on tamoxifen compared with 78% of younger women on tamoxifen. After three years, only 3% of women in their 60s experienced a recurrence of cancer compared with 10% of younger women.

The lead researcher, Dr. Jonathan Gollege of the Charing Cross Hospital in London, noted that women (regardless of age) who do not receive tamoxifen or radiation therapy after early stage breast cancer are most likely to experience a recurrence of breast cancer. Gollege also said that younger women may not respond as well to tamoxifen therapy because their breast cancer is usually more aggressive. The research contradicts recent studies that call for standard breast cancer treatment among patients regardless of age. Many older patients may benefit from tamoxifen alone while some younger patients may initially need to combine tamoxifen with another form of treatment to successfully eliminate breast cancer.

Several previous studies have also shown that the benefits of tamoxifen may be related the age of the patient. In general,

  • women under 40 years of age typically show the least response to tamoxifen.
  • women between the ages of 40 and 50 years of age typically show some response.
  • women over 50 typically benefit the most from tamoxifen.

Some early-stage breast cancer patients over 50 years of age who are treated with tamoxifen may be able to significantly reduce (or sometimes completely eliminate) the size of their breast tumors so that surgeons may perform lumpectomy (surgical removal of a breast lump) instead of mastectomy (surgical removal of the affected breast). 

Researchers are not certain why young women do not always respond as well to tamoxifen but believe it may be related to the amount of estrogen produced in their bodies. Because younger women have higher levels of estrogen, their breast cancers may be more aggressive. When a woman reaches menopause (typically around 50 years of age), her body stops producing estrogen.

Tamoxifen is currently the most widely prescribed drug used to treat breast cancer since its approval by the U.S. Food and Drug Administration (FDA) in 1978. Recently, tamoxifen has also been shown to be effective in preventing breast cancer in some women who are at high risk for the disease.

Women with early stage breast cancer are usually prescribed tamoxifen for two to five years. When taken for five years, studies have shown that tamoxifen prevents the recurrence of the original breast cancer and also helps prevent breast cancer in the opposite breast. Women considering tamoxifen for the treatment or prevention of breast cancer should discuss the drug with their physician.

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