February 5, 2009

Oncotype DX™— Individualizing Cancer Therapy

Women with early breast cancer now have a tool that can help individualize their treatment choices. Oncotype DX™ is a test that can help predict whether a woman with hormone-positive breast cancer that has not spread to her axillary (under the arm) lymph nodes will benefit from chemotherapy.

Adjuvant therapy refers to treatment used after the surgical removal of early breast cancer. Adjuvant therapy is used to kill undetectable cancer cells that may remain in the body following surgery. Chemotherapy has demonstrated an improvement in survival when used as adjuvant therapy in early breast cancer; however, it is estimated that approximately 85% of these women do not derive benefit from chemotherapy and are unnecessarily exposed to its side effects, increased medical costs, and increased time dedicated to treatment. Therefore, it is crucial to determine which of these patients will achieve benefit from chemotherapy so that therapy may be individualized.

Gene expression profiling explores the patterns of genes that are active in tumor cells. Studies suggest that gene expression may provide information about prognosis or likely response to treatment in several types of cancer, including breast cancer.

Oncotype DX is a test that performs gene expression profiling. The test is indicated for patients with newly diagnosed stage I or II, node-negative, estrogen-receptor positive breast cancer who will be treated with tamoxifen. A panel of 21 genes is evaluated to predict a patient’s 10-year risk of cancer recurrence. The test classifies patients as being at high, intermediate, or low risk of recurrence based on a Recurrence Score™. The Recurrence Score ranges from 0 to 100, with a higher score indicating a greater risk of recurrence.

Previous reports have suggested that in addition to predicting a patient’s risk of breast cancer recurrence, Oncotype DX may also provide information about likely response to chemotherapy. In order to further evaluate the link between Oncotype DX’s Recurrence Score and response to chemotherapy, researchers conducted a study among 651 patients with node-negative, estrogen receptor-positive breast cancer.[1]

  • Oncotype DX classified 353 patients (54%) as having a low risk of recurrence (Recurrence Score less than 18), 124 patients (21%) as having an intermediate risk of recurrence (Recurrence Score between 18 and 30), and 164 patients (25%) as having a high risk of recurrence (Recurrence Score greater than 30).
  • The addition of chemotherapy to tamoxifen improved survival for women at high risk of recurrence based on the Recurrence Score, but did not improve survival among women at low or intermediate risk of recurrence.
  • Among women at high risk of recurrence, the probability of surviving for 10 years without a distant cancer recurrence was 61% among women treated with tamoxifen alone, and 88% among women treated with tamoxifen and chemotherapy.
  • Among women at low or intermediate risk of recurrence, the probability of surviving for 10 years without a distant cancer recurrence was similar whether or not a woman received chemotherapy. The researchers note, however, that additional study of the risks and benefits of chemotherapy is needed for women with an intermediate risk of recurrence.

The researchers conducting this trial concluded that Oncotype DX not only provides information about risk of recurrence in women with node-negative, estrogen receptor-positive breast cancer, but also provides information about the likely benefit of chemotherapy.

To further explore the use of Oncotype DX in guiding chemotherapy decisions, a newly opened clinical trial—the TAILORx trial—will enroll more than 10,000 breast cancer patients from the U.S. and Canada.[2] The study will focus on breast cancer that is estrogen receptor-positive and/or progesterone receptor-positive, does not involve lymph nodes, and is HER2/neu negative.

Women in the trial will be assigned to a treatment group based on their Recurrence Score:

  • Women with a high Recurrence Score (greater than 25) will receive adjuvant treatment with chemotherapy plus hormonal therapy.
  • Women with a low Recurrence Score (less than 11) will receive adjuvant treatment with hormonal therapy alone.
  • Women with an intermediate Recurrence Score (from 11 to 25) will be randomly assigned to receive adjuvant treatment with either hormonal therapy alone or hormonal therapy plus chemotherapy.

The main focus of the study is to evaluate the role of the Oncotype DX test in women with an intermediate risk of recurrence. In these women, the benefit of chemotherapy remains uncertain.

Patients who are diagnosed with early, hormone-positive breast cancer may wish to speak with their physician regarding their individual risks and benefits of Oncotype DX or participation in the TAILORx trial. Oncotype DX is now covered by Medicare.


[1] Paik S, Tang G, Shak S et al. Gene Expression and Benefit of Chemotherapy in Women with Node-Negative, Estrogen Receptor-Positive Breast Cancer. Journal of Clinical Oncology. Early online publication May 23, 2006.

[2] National Cancer Institute. Press Release. Personalized Treatment Trial for Breast Cancer Launched. Available at: http://www.cancer.gov/newscenter/pressreleases/TAILORxRelease.  Accessed May 26, 2006.

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Tags: Breast Cancer, Uncategorized