SAN ANTONIOThe 21-gene recurrence score assay (Oncotype DX) was applied to early breast cancer patients with hormone-receptor and axillary lymph node positivity in two studies reported at the 2007 San Antonio Breast Cancer Symposium. Their findings suggest that the recurrence score can identify subsets most likely to benefit from chemotherapy.
Kathy S. Albain, MD, professor of medicine, Loyola University Chicago Stritch School of Medicine, reported the correlation of the 21-gene assay with outcomes in patients from the SWOG 8814 study (abstract 10).
SWOG 8814 previously found that six cycles of cyclophosphamide, doxorubicin, and fluorouracil followed by 5 years of tamoxifen (CAF-T) was associated with superior disease-free survival (DFS) and overall survival (OS) over tamoxifen alone in postmenopausal patients with node-positive, estrogen-receptor (ER)-positive breast cancer.
Dr. Albain's group showed that the recurrence score (RS) is prognostic for DFS (P = .017) and OS (P = .003) in patients treated with tamoxifen alone.
Low, intermediate, and high RSs were associated with 10-year DFS of 60%, 49%, and 43%, respectively, and with 10-year OS of 77%, 68%, and 51%, respectively.
Next, they determined the predictive value of the RS. DFS and OS were compared in patients treated with tamoxifen only vs those who also received chemotherapy.
While a significant improvement in DFS and OS was achieved by adding CAF in patients with a high RS, there was no benefit in patients with a low RS. The interaction of RS with treatment effect was true for patients with 1 to 3 positive nodes and 4 or more nodes.