According to the results of a study presented at the 2007 San Antonio Breast Cancer Symposium, the Oncotype DX test may help guide chemotherapy decisions among women with node-positive, estrogen receptor-positive breast cancer.
Although chemotherapy is recommended for many women with early-stage breast cancer, the benefit of chemotherapy varies. Identifying in advance those women who are most likely to benefit from chemotherapy may allow for more individualized treatment. This would allow women who are unlikely to benefit from chemotherapy to avoid the toxic effects of treatment.
Oncotype DX is a genomic test that predicts the likelihood of a cancer recurrence, the likelihood of benefit from chemotherapy, and the likelihood of survival in patients with newly diagnosed breast cancer that has not spread to their lymph nodes (node-negative) and is estrogen receptor (ER)-positive.
Oncotype DX evaluates the activity of 21 genes from a sample of the patient’s cancer to determine the patient’s Recurrence Score. The Recurrence Score ranges from 0 to 100, with a higher score indicating a greater risk of recurrence.
In addition to its established role among women with node-negative breast cancer, Oncotype DX may also help predict recurrence risk and chemotherapy benefit among women with node-positive breast cancer.
To explore the use of Oncotype DX among postmenopausal women with node-positive, ER-positive breast cancer, researchers evaluated information from a Phase III clinical trial. Information was available for 367 patients; 148 patients had been treated with tamoxifen alone, and 219 had been treated with chemotherapy plus tamoxifen.
Forty percent of the study participants were classified as low risk (Recurrence Score less than 18), 28% were classified as intermediate risk (Recurrence Score 18-30), and 32% were classified as high-risk (Recurrence Score 31 or higher).
- In the women treated with tamoxifen alone, higher Recurrence Scores were linked with worse disease-free survival.
- Among women with a low Recurrence Score, disease-free and overall survival were not significantly improved by the addition of chemotherapy. Ten-year disease-free survival was 60% among women treated with tamoxifen alone and 64% among women treated with chemotherapy plus tamoxifen.
- Among women with a high Recurrence Score, disease-free and overall survival were significantly improved by the addition of chemotherapy. Ten-year disease-free survival was 43% among women treated with tamoxifen alone and 55% among women treated with chemotherapy plus tamoxifen.
These results suggest that Oncotype DX may help guide decisions about the need for chemotherapy among patients with node-positive, ER-positive breast cancer. The addition of chemotherapy significantly improved outcomes among women with a high Recurrence Score. Furthermore, the researchers note: “A low [Recurrence Score] may define a group of women with positive nodes who do not appear to benefit from anthracyline-based adjuvant chemotherapy.”
Reference: Albain K, Barlow W, Shak S et al. Prognostic and predictive value of the 21-gene recurrence score assay in postmenopausal, node-positive, ER-positive breast cancer (S8814,INT0100). Presented at the 30th Annual San Antonio Breast Cancer Symposium. San Antonio, TX, December 13-16, 2007. Abstract #10.
Oncotype DX Provides Information About Hormone Receptor Status of Breast Cancer (9/14/2007)
Copyright © 2018 CancerConnect. All Rights Reserved.