Oncotype DX® and Clinical Characteristics Influence Chemotherapy Decisions in Early Breast Cancer

Among women with early breast cancer who underwent testing with Oncotype DX, decisions about the need for chemotherapy were influenced by the Oncotype DX recurrence score as well as by the size and grade of the cancer. These results were presented at the 2009 annual meeting of the American Society of Clinical Oncology.

Although chemotherapy is recommended for many women with early-stage, node-negative breast cancer, the benefit of chemotherapy varies. Identifying in advance those women who are most likely to benefit from chemotherapy may allow for more individualized treatment.

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 has been added to medical guidelines for early-stage breast cancer.

To explore the extent to which the Oncotype DX recurrence score and other factors influence chemotherapy decisions among women with early breast cancer, researchers at the Dana-Farber Cancer Institute conducted a study among 269 women with early breast cancer who had undergone testing with Oncotype DX. The women all had breast cancer that was ER-positive, HER2-negative, and node-negative.

Based on Oncotype DX testing, 50% of the women were classified as having a low risk of recurrence (recurrence score less than 18); 41% had an intermediate risk of recurrence (recurrence score between 18 and 30); and 9% had a high risk of recurrence (recurrence score greater than 30).

Use of chemotherapy varied significantly by Oncotype DX recurrence score. Adjuvant chemotherapy was given to 7% of women with a low recurrence score, 42% of women with an intermediate recurrence score, and 86% of women with a high recurrence score.

Use of chemotherapy also varied by cancer size and grade. The grade of the cancer refers to how abnormal the cancer cells look under a microscope. Women with large or high-grade cancers were more likely than women with small or low-grade cancers to receive chemotherapy.

This study was conducted at a single institution, and the results may not apply to all women. Nevertheless, the results suggest that decisions about the need for chemotherapy among women with early, ER-positive breast cancer are influenced by the Oncotype DX recurrence score as well as by traditional clinical characteristics of the cancer such as size and grade.

Reference: Gold JM, Najita JS, Lester S et al. Personalizing treatment in early-stage breast cancer: the role of standard clinical factors and genomic information in adjuvant chemotherapy decision making. Presented at the 2009 annual meeting of the American Society of Clinical Oncology (ASCO), May 29-June 2, 2009, Orlando, FL. Abstract 572.

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