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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Sequential Chemotherapy Benefits Node-positive Breast Cancer Patients

Women with operable node-positive breast cancer experienced a survival benefit from sequential administration of doxorubicin, cyclophosphamide, and TaxotereR (docetaxel). These findings were recently published in The New England Journal of Medicine.[1]

Effective treatment of node-positive breast cancer often involves both local and systemic therapy. Local therapy consists of surgery and/or radiation and is directed at removing or destroying cancer cells in or near the breast. Systemic therapy is directed at destroying cancer cells throughout the body, and may include chemotherapy, targeted therapy, and/or hormonal therapy.

Anthracycline and taxane chemotherapy drugs are commonly used in the treatment of breast cancer. To compare three different approaches to administering chemotherapy, researchers conducted a study known as the National Surgical Adjuvant Breast and Bowel Project B-30 trial.

In this multicenter Phase III trial, 5,351 breast cancer patients with node-positive disease who had undergone total mastectomy or lumpectomy were randomized to receive eight cycles of treatment with sequential doxorubicin, cyclophosphamide, and Taxotere (ACT) over 24 weeks, concurrent TAC over 12 weeks, or a regimen of doxorubicin/Taxotere over 12 weeks.? In the concurrent TAC arm, all three drugs were administered together; in the sequential ACT arm, doxorubicin and cyclophosphamide were administered followed by Taxotere. After a median follow-up of six years, disease-free survival and overall survival were improved in the sequential ACT arm.

Overall survival was 83% in the sequential ACT arm, 79% in the concurrent ACT arm, and 79% in the doxorubicin/Taxotere arm.Disease-free survival was 74% in the sequential ACT arm, 69% in the concurrent TAC arm, and 69% in the doxorubicin/Taxotere arm.

The researchers concluded that sequential administration of ACT provided a statistically significant 17% reduction in mortality compared with doxorubicin/Taxotere and a nonsignificant 14% reduction in mortality compared with the concurrent TAC arm. In addition, patients who experienced amenorrhea (absence of menstrual bleeding) for six months or more experienced an improved overall survival in all arms of the study. ?The clinical significance of this finding is uncertain, but it of great interest and will lead to further investigation.? Studies are ongoing that continue to evaluate strategies to improve treatment for node-positive breast cancer patients.

Reference:

[1] Swain SM, Jeong J-H, Geyer CE, et al. Longer therapy, Iatrogenic amenorrhea, and survival in early breast cancer. New England Journal of Medicine. 2010; 362:2053–65.

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