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

Oncotype DXR Predicts Recurrence Risk in Node-negative and Node-positive Breast Cancer Treated with Tamoxifen or Arimidex
Among postmenopausal women with early, hormone receptor-positive breast cancer treated with either tamoxifen (NolvadexR) or ArimidexR (anastrozole), the Oncotype DX test predicts the risk of distant cancer recurrence in both node-negative and node-positive patients. These results were published in the Journal of Clinical Oncology.

Oncotype DX is a genomic test that has been shown to predict the likelihood of distant cancer recurrence and the likelihood of chemotherapy benefit in women with early-stage, estrogen receptor-positive breast cancer that is treated with tamoxifen. The test evaluates the activity of 21 genes from a sample of the patient’s cancer to determine the patient’s Recurrence Score. The higher the Recurrence Score, the higher the risk of cancer recurrence. Oncotype DX has been added to U.S. medical guidelines for early-stage breast cancer.

The current analysis assessed how the Recurrence Score performed among women treated with the aromatase inhibitor drug Arimidex and among those with node-positive breast cancer.

The researchers collected information from 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. Study participants received hormonal therapy with either tamoxifen or Arimidex.

The Recurrence Score (RS) predicted the risk of distant cancer recurrence among women with node-negative and node-positive breast cancer:

Among women with node-negative breast cancer, nine-year risk of distant cancer recurrence was 4% among women with a low Recurrence Score, 12% among women with an intermediate Recurrence Score, and 25% among women with a high Recurrence Score.Among women with node-positive breast cancer, nine-year risk of distant cancer recurrence was 17% among women with a low Recurrence Score, 28% among women with an intermediate Recurrence Score, and 49% among women with a high Recurrence Score.

The relationship between Recurrence Score and risk of distant cancer recurrence was similar regardless of the type of hormonal therapy that the women received.

This study suggests that the Oncotype DX test provides 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 Arimidex.

Reference: Dowsett M, Cuzick J, Wales C et al. Prediction of risk of distant recurrence using the 21-gene recurrence score in node-negative and node-positive postmenopausal patients with breast cancer treated with anastrozole or tamoxifen: a TransATAC study. Journal of Clinical Oncology [early online publication]. March 8, 2010.

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Arimidex and Faslodex Combined Show Promise in Metastatic Breast Cancer

The combination of anastrozole (ArimidexR) and fulvestrant (FaslodexR) prolonged overall survival and progression-free survival in postmenopausal women with previously untreated hormone receptor-positive metastatic breast cancer compared to Arimidex alone, according to the results of a study published in the New England Journal of Medicine. ?

Each year roughly 200,000 U.S. women are diagnosed with breast cancer. Many of these breast cancers are hormone receptor-positive, meaning that they are stimulated to grow by the circulating female hormones estrogen and/or progesterone. Treatment of hormone receptor-positive breast cancer often involves hormonal therapies that suppress or block the action of estrogen.?

Arimidex is a type of hormone therapy known as an aromatase inhibitor and works by suppressing the production of estrogen in postmenopausal women. Faslodex is a type of hormonal therapy known as an estrogen receptor antagonist and works by binding to estrogen receptors and degrading them. Both drugs are approved for the treatment of postmenopausal women with metastatic breast cancer. ?

To evaluate the drugs in combination, researchers conducted a trial involving 694 women who were randomly assigned to receive Arimidex alone or Arimidex and Faslodex combined. All women in the study had cancer that was hormone-receptor positive and none of them had been previously treated with chemotherapy, immunotherapy, or hormone therapy to stop the spread of disease. ?

The results indicated that the combination was superior to the single agent therapy. The median progression-free survival was 15 months in the combination group, compared to 13.5 months in the Arimidex alone group. Overall survival was also longer in the combination group—47.7 months compared to 41.3 months in the single agent group. Of note, not all patients assigned to anastrozole subsequently received fulvestrant.? Furthermore, another study looking at the combination of anastrozole and fulvestrant failed to show superiority over anastrozole alone.?

Both groups had mild to moderate side effects such as joint pain and hot flashes. Although the rate was higher in the combination group, it was not statistically significant. ?

The researchers concluded that the combination of Arimidex and Faslodex was superior to Arimidex alone for the treatment of hormone-receptor positive metastatic breast cancer—even though the dose of Faslodex was below the current standard dose. However, the results of this study have to be reconciled with the less favorable results from the other study that evaluated this combination. ?Many oncologists continue to believe that the optimal hormonal therapy approach for women newly diagnosed with metastatic breast cancer remains uncertain.?

Reference:?

Mehta RS, Barlow WE, Albain KS, et al. Combination anastrozole and fulvestrant in metastatic breast cancer. New England Journal of Medicine. 2012; 367:435-444.?

Posted August 6, 2012

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