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Types of Cancer > Breast Cancer > Resources

OncoType Dx: Predicting Cancer Recurrence

Carolyn Vachani, RN, MSN, AOCN
Affiliation: The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 29, 2008

There are an estimated 100,000 new cases of early stage, node-negative, estrogen receptor-positive breast cancer each year in the United States. These patients are frequently treated with adjuvant chemotherapy (chemotherapy given after surgery), although only a small portion of these patients will ultimately derive any benefit from this treatment, in terms of both living longer and living without breast cancer recurrence. This means a significant number of patients are subjected to the toxicities of therapy for little or no gain. Determining which patients will benefit from chemotherapy has long been the million-dollar question facing clinicians, but now there is a new tool in the box.

The Oncotype Dx™ Test

Oncotype Dx TM is a laboratory test that evaluates a sample of the breast tumor to predict a woman's risk of developing a recurrence over 10 years and the benefit she would derive from adjuvant chemotherapy. The test is specifically designed for women with stage I or II, estrogen receptor positive breast cancer that has not spread to the lymph nodes. The test assumes that the woman will be taking hormone therapy as part of her therapy, so it cannot be used to predict risk without using this therapy. The test has not been validated for women with tumors that do not fit these criteria (including DCIS or LCIS), but studies are evaluating its use in a variety of situations.

Is the Test Right for Me?

To better understand if this test is right for you, an understanding of normal breast tissue is helpful. Breast tissue is composed of lobules, which produce milk; and ducts, which carry the milk to the nipple. Breast cancer starts in a duct or a lobule, and where it starts, along with its appearance under the microscope, are what determine the type of breast cancer one has (i.e. ductal cancer vs. lobular cancer). The type of breast cancer can dictate some of the treatment choices, although many types are treated similarly.

In addition to the type, the cancer can be non-invasive, which means it does not spread beyond the lobule or duct; or invasive, which means it has spread beyond the lobule or duct. The Oncotype Dx™ test is for women with early stage invasive breast cancer. More specifically, stages I & II tumors, defined as:

• Stage I: The tumor is 2 centimeters or less and does not involve the lymph nodes.
• Stage II: the tumor is 2-5 centimeters in size. Stage II tumors can involve 1-3 lymph nodes, but in order to utilize Oncotype Dx TM, there cannot be any lymph node involvement.

The tumor must also be estrogen receptor-positive. This information is found on your pathology report and means that the cancer is likely to respond to hormone therapy. The Oncotype Dx TM test is used to help you and your physician determine if chemotherapy is right for you. Therefore, it should be done before beginning any therapy for your cancer.