Among women with node-negative, estrogen receptor-positive breast cancer, the Oncotype DX test predicts the likely benefit of chemotherapy. These results were published in the Journal 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. This would allow women who are unlikely to benefit from chemotherapy to avoid the toxic effects of treatment.
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. The test evaluates a panel of 21 genes to predict a patient’s ten-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.
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 conclude 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.
Reference: 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.
Oncotype DX Predicts Local and Regional Recurrences in Breast Cancer Patients (12/15/2005)
Oncotype DX Changes Treatment Decisions in One Quarter of Breast Cancer Patients (12/15/2005)
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