According to an article recently published in the journal Cancer, premenopausal women with breast cancer whose cancer has spread to at least four lymph nodes derive the most benefit from treatment with aromatase inhibitors administered following tamoxifen. Postmenopausal women with cancer that has spread to three or fewer lymph nodes appear to only derive 1–2% benefit from the addition of an aromatase inhibitor following tamoxifen.
A majority of breast cancers are estrogen receptor-positive (ER-positive), meaning that the female hormone estrogen stimulates their growth. Depriving ER-positive breast cancers of estrogen can slow the growth of these cancers.
For many years tamoxifen has been a mainstay of hormonal therapy for breast cancer. Tamoxifen acts by blocking estrogen receptors. More recently, however, drugs known as aromatase inhibitors have produced promising results. Aromatase inhibitors are now replacing tamoxifen as initial therapy for a significant portion of breast cancer patients. However, questions remain about the order agents are administered or optimal duration of therapy. Researchers continue to evaluate data and conduct clinical trials to answer these questions.
In an attempt to identify which patients may benefit most from additional treatment with aromatase inhibitors, researchers from Pennsylvania recently evaluated data from 471 women who had been diagnosed with early breast cancer. The study included women who had been treated with breast-conserving therapy (surgery in which only the area of cancer and surrounding tissue is removed), removal of axillary (under the arm) lymph nodes, radiation therapy, and tamoxifen, with or without chemotherapy. The women had remained cancer-free for at least five years. Follow-up was 8.25 years. Researchers compared these results to results from larger studies evaluating the addition of aromatase inhibitors following treatment with tamoxifen among women with early breast cancer.
- Women with cancer spread to four or more lymph nodes or those who were premenopausal had significantly less chance of cancer-free survival with tamoxifen alone than postmenopausal women or those with cancer spread to three or fewer lymph nodes.
- Younger women and those with cancer spread to the least amount of lymph nodes had improved overall survival with tamoxifen alone compared to the other women.
- Overall, the addition of aromatase agents following tamoxifen would have achieved only a 1–2% benefit in terms of cancer-free survival among all women.
The researchers concluded that the addition of aromatase agents following treatment with tamoxifen improves cancer-free survival by 1–2% among women with early breast cancer. However, it appears that women who are premenopausal and those whose cancer has spread to four or more lymph nodes would derive greater benefit from the addition of aromatase agents following tamoxifen.
Women with early, hormone-positive breast cancer may wish to speak with their physician regarding their individual risks and benefits of all types of hormone therapy.
Reference: Freedman G, Anderson P, Li T, et al. Identifying Breast Cancer Patients Most Likely to Benefit from Aromatase Inhibitor Therapy after Adjuvant Radiation and Tamoxifen. Cancer. Early online publication. October 23, 2006. DOI: 10.1002/cncr.22291.