Two studies published in the Journal of Clinical Oncology have reported that chemotherapy improves survival among elderly women with hormone receptor-negative, lymph node-positive breast cancer.
Although clinical trials have established the efficacy of chemotherapy for breast cancer, elderly women (women over the age of 70) were under-represented in these studies. As a result, the optimal use of chemotherapy in this age group remains uncertain.
To explore patterns of chemotherapy use among elderly breast cancer patients and to assess the effect of chemotherapy on survival, two separate studies evaluated information from a large, national cancer registry. Both of the studies were “observational.” In an observational study, the researchers do not control the medications that women take. Rather, the researchers observe what happens to women after they and their physicians choose what medications to take.
A limitation of this type of study is that the women who receive chemotherapy are likely to be different from women who do not receive chemotherapy, and these differences may affect the study results. Researchers attempt to account for differences between groups when they analyze the data, but some differences may be difficult to identify or measure.
- Use of chemotherapy in this population of older women increased over time, from 7.4% in 1991 to 16.3% in 1999.
- A benefit of chemotherapy on survival was observed only among women who were estrogen receptor-negative and lymph node-positive. Among these women, chemotherapy reduced breast cancer mortality by 28%. This benefit was observed among women over the age of 70 as well as younger women.
The researchers concluded that chemotherapy significantly reduced the risk of death among older women with estrogen receptor-negative, lymph node-positive breast cancer.
- Once again, use of chemotherapy increased over time.
- Use of chemotherapy reduced the risk of death by 15%. The reduction in risk of death was especially apparent among women with lymph node-positive cancer. This survival benefit did not vary by age.
The researchers concluded that these results suggest that chemotherapy is linked with improved survival among older women with hormone receptor-negative breast cancer, particularly among women with node-positive or other high-risk cancer.
An accompanying editorial notes that the increasing use of chemotherapy among elderly breast cancer patients may be warranted, given the improved survival among estrogen receptor-negative and lymph node-positive patients observed in these two studies. The editorial notes, however, that there is still considerable uncertainty about which subgroups of older women are most likely to benefit from chemotherapy.
 Elkin EB, Hurria A, Mitra N, Schrag D, Panageas KS. Adjuvant Chemotherapy and Survival in Older Women with Hormone Receptor-Negative Breast Cancer: Assessing Outcome in a Population-Based, Observational Cohort. Journal of Clinical Oncology . 2006;24:2757-2764.