Oncotype DX® Predicts Recurrence Risk in Node-negative and Node-positive Breast Cancer Treated with Tamoxifen or Arimidex®

Among women with early, hormone receptor-positive breast cancer treated with either tamoxifen (Nolvadex®) or Arimidex® (anastrozole), the Oncotype DX test predicts the risk of distant cancer recurrence in both node-negative and node-positive patients. These results were presented at the 2008 San Antonio Breast Cancer Symposium.

Oncotype DX is a genomic test that previously has been shown to predict 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. Oncotype DX is covered by several large health coverage policies and has been added to medical guidelines for early-stage breast cancer.

The current analysis focused on 1,231 women who participated in the ATAC (Arimidex, Tamoxifen, Alone or in Combination) study. The study enrolled postmenopausal women with early, hormone receptor-positive breast cancer, and compared two different hormonal therapies: tamoxifen and Arimidex® (anastrozole; an aromatase inhibitor). The study demonstrated a lower risk of cancer recurrence with Arimidex than with tamoxifen.

Information about distant cancer recurrences was collected over a nine-year period among both node-negative and node-positive patients. Researchers then assessed the ability of the Oncotype DX test to predict these recurrences by evaluating the correlation between the Oncotype DX Recurrence Score and the likelihood of distant recurrence.

  • Among both node-negative and node-positive patients treated with either Arimidex or tamoxifen, higher Recurrence Scores were linked with a higher risk of distant recurrence.

This is the largest study of Oncotype DX conducted to date. It suggests that the Oncotype DX test provides important information about risk of distant cancer recurrence in both node-negative and node-positive, hormone-receptor positive breast cancer. Furthermore, Oncotype DX was predictive of distant recurrence risk among women treated with tamoxifen as well as women treated with the aromatase inhibitor Arimidex.

Reference: Dowsett M, Cuzick J, Wales C et al. Risk of distant recurrence using oncotype DX in postmenopausal primary breast cancer patients treated with anastrozole or tamoxifen: a TransATAC study. Presented at the San Antonio Breast Cancer Symposium. December 13, 2008. Abstract 53.

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