More than 1.15 million women around the world are diagnosed with breast cancer every year. How breast cancer is treated varies according to a number of factors, such as the stage of the cancer when diagnosed, the age of the individual, and the type of medical care available.

When breast cancer is detected early, it may be possible to surgically remove the entire tumor. However, most women are advised to have additional treatment with radiation , chemotherapy , and/or hormonal therapy to reduce the risk of recurrence.

For the past several decades, hundreds of breast cancer trials have been underway to study the effects of different breast cancer treatments. In 1984-85, researchers formed the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), which has since been gathering data from all of the trials involving the treatment of early-stage breast cancer.

The findings from the most recent EBCTCG analysis, which looks at 5, 10, and 15-year survival rates for various treatments, are reported in the May 14, 2005 issue of the Lancet . Overall, this study found that chemotherapy and hormonal therapy treatments have a greater impact on breast cancer survival and recurrence rates at 15 years than at 5 years.

About the Study

The researchers reviewed the results of 194 randomized trials that began by 1995, involving 145,000 women from all over the world. The researchers gathered standard information on every woman, such as age and allotted treatment, as well as information on whether or not the tumor had spread to the lymph nodes (node-positive), and whether the tumor was positive for estrogen receptors (estrogen-positive), both of which affect prognosis.

The trials reviewed by the authors all involved one or more of the following treatments, which were common treatments in the 1980’s when most of these trials began:

  • CMF (cyclophosphamide, methotrexate, fluorouracil)-based chemotherapy
  • Anthracyline-based chemotherapy combinations
  • Tamoxifen (a medication that interferes with the activity of estrogen)
  • Ovarian ablation (removing the ovaries to stop them from working) or suppression

They grouped the results into five, 10, and 15-year outcomes, with the main outcome measures being breast cancer recurrence and mortality.

The Findings

Overall, anthracycline-based treatment was significantly more effective than CMF-based treatment at reducing the annual breast cancer death rates. Six months of anthracycline-based chemotherapy decreased the annual breast cancer death rate by 38% for women who were younger than 50 years of age when diagnosed, and by 20% for those were between the ages of 50 and 69 when diagnosed.

For women with estrogen receptor positive tumors, five years of tamoxifen therapy—regardless of whether or not they had chemotherapy—decreased the annual breast cancer death rate by 31%. Undergoing ovarian ablation or suppression also significantly decreased breast cancer mortality, but only in the absence of other treatments.

Based on these results, the authors concluded that middle aged women who are diagnosed with estrogen-positive breast cancer, can cut their mortality rate in half over the 15 years following their diagnosis by undergoing six months of anthracycline-based chemotherapy and then taking tamoxifen for five years.

How Does This Affect You?

This landmark study strengthens the case for following surgery and radiation with chemotherapy and hormonal therapy when treating early-stage breast cancer. Specifically, this study suggests that anthracycline-based therapies should be used over CMF-based therapies, and that chemotherapy should be followed by tamoxifen in women with estrogen-positive tumors.

This study also demonstrates that the true effect of these treatments may not be realized until 15 years down the road, at which point rates of cancer recurrence and death were significantly lower than at five years.

The authors of the study point out that these findings are based on treatments that were tested in the 1980’s and that further improvements in long term survival may be possible with some of the newer drugs currently available. For now, however, doctors should consider the results of this study when determining treatment plans for women age 69 and under. As more trials are conducted to incorporate newer drugs or different combinations of older drugs, the recommendations for treating early-stage breast cancer will continue to evolve.

Women who are diagnosed with breast cancer should thoroughly review all of their treatment options with their doctor. The most suitable treatment options will vary, depending on factors such as cancer stage, age, menopausal status, and whether the tumor is estrogen receptor positive.