Long-Term Follow-Up of Node-Negative, Estrogen Receptor-Positive Breast Cancer
According to results recently published in the Lancet, optimal treatment for early breast cancer cannot be standardized, but must include the consideration of risk factors of the patient and their cancer.
Breast cancer is diagnosed in approximately 250,000 women annually in the United States alone. Treatment options vary according to the extent, or spread, of the cancer and research continues to emerge indicating that specific variables existent either in patients or their cancer result in different prognoses. Recent attention has been focused on individualizing treatment with the identification of specific variables and long-term outcomes of patients. Early, or localized, breast cancer refers to cancer that has not spread to distant sites in the body. Treatment for localized breast cancer may consist of surgery, radiation, chemotherapy and/or hormone therapy. The role of chemotherapy remains controversial in very early breast cancers.
Hormone-positive breast cancer, also referred to as estrogen or progesterone receptor-positive breast cancer, refers to cancer that is stimulated to grow from the exposure to the female hormones, estrogen and/or progesterone. Hormone therapy is treatment that reduces the amount of these hormones available to the cancer cells, thus inhibiting their growth stimulus. Newer hormone agents have recently emerged in the clinical setting and researchers are still piecing together optimal timing and sequencing of specific hormone agents.
Researchers associated with the National Surgical Adjuvant Breast and Bowel Projects (NSABP) recently released long-term data from two large clinical trials evaluating women with early breast cancer. The first trial, referred to as B-14, included nearly 3,000 women with hormone-positive, node-negative (cancer had not spread to lymph nodes under the arm) breast cancer. Following the surgical removal of cancer, approximately half of the patients were treated with 5 years of the anti-estrogen agent Nolvadex® (tamoxifen) and the other half of patients received placebo (inactive substitute). At 15 years follow-up, cancer-free survival was 78% for women treated with tamoxifen, compared with 65% for patients who received placebo. Overall survival was 71% for patients treated with tamoxifen, compared with 65% for those who received placebo. Patients with a higher degree of estrogen receptor expression benefited more from treatment with tamoxifen than those with a lesser degree of estrogen receptor expression. Furthermore, women aged 50-59 years did not significantly benefit in terms of overall survival when treated with tamoxifen, but did benefit in terms of cancer-free survival. All other age groups demonstrated a survival improvement with tamoxifen.
The second trial, referred to as B-20, included over 1,500 women with node-negative, estrogen receptor-positive breast cancer. Following the surgical removal of the cancer, approximately half of the women were treated with 5 years of tamoxifen and the other half were treated with tamoxifen plus the chemotherapy regimen CMF (cyclophosphamide, methotrexate and 5-fluorouracil). At 12 years follow-up, cancer-free survival was 89% for patients treated with tamoxifen/CMF, compared to 79% for those treated with tamoxifen alone. Overall survival was 87% for those treated with tamoxifen/CMF, compared to 83% for those treated with tamoxifen alone. Women aged 49 years or younger derived the most benefit in terms of cancer-free and overall survival from the addition of chemotherapy, while women over the age of 60 did not achieve a benefit from the addition of chemotherapy. The data also suggested that women with a lower degree of estrogen receptor expression benefited more from chemotherapy than those with higher receptor expression.
These long-term results add to data that can help women and their physician make choices about treatment options. However, these complex results are difficult to simplify and the authors stress the importance of considering all risk factors before making a treatment decision. It is important that patients discuss their individual risks and benefits of different treatment options with their physician.
Reference: Fisher B, Jeong J-H, Bryant J, et al. Treatment of lymph-node-negative, estrogen-receptor-positive breast cancer: long-term findings from National Surgical Adjuvant Breast and Bowel Project randomized clinical trials. The Lancet. 2004;364:858-868.
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