Relatively few breast cancer survivors who are disease-free for 5 years after starting a systemic adjuvant therapy such as chemotherapy or tamoxifen experience a recurrence, but preventive treatments are needed to reduce the relapse rate further.

Dr. Abenaa Brewster of the University of Texas M.D. Anderson Cancer Center and her colleagues tracked breast cancer recurrence in 2,838 women treated with chemotherapy, tamoxifen, or both, between 1985 and 2001. The disease recurred in 7 percent of survivors diagnosed with stage I breast cancer, 11 percent of women treated for stage II disease, and 13 percent of women with stage III disease.

Along with stage of cancer, tumor grade, hormone-receptor status, and endocrine therapy were associated with risk of recurrence. Overall, however, 89 percent of the study population did not experience a recurrence at 5 years (approximately 10 years after a woman's initial diagnosis), and 80 percent did not experience a recurrence at 10 years (approximately 15 years after diagnosis).

While the overall results should be encouraging for patients, the study also highlighted the need to develop risk-reduction strategies for premenopausal breast cancer survivors, the researchers note. Extended adjuvant therapy with letrozole (Femara) is available for postmenopausal women with hormone receptor-positive tumors who have completed 5 years of tamoxifen therapy. But nothing similar is available for premenopausal women.

A limitation of the study is that it did not include women who received adjuvant therapy with trastuzumab (Herceptin) or 5 years of an aromatase inhibitor. Data were not available on HER2/neu status, and few women in the group received an aromatase inhibitor.