Oncotype DX Test for Breast Cancer

Living with breast cancer is challenging for millions of women today. Some new ways of evaluating the likelihood that breast cancer will recur may allow doctors to determine who might benefit most from chemotherapy and other treatments.

With any cancer, the tumor cells divide uncontrollably. Cancer cells can then invade nearby tissues and spread through the bloodstream and lymphatic system to other parts of the body (called metastasizing). To kill cancer cells, doctors have routinely given patients with breast cancer the standard prescription: tumor removal via mastectomy or sometimes lumpectomy, usually followed by radiation and chemotherapy.

Until now, doctors have not been able to tell which women are at higher risk for breast cancer recurrence. Rather than take chances, every patient received the standard course of chemotherapy, which often has toxic side effects for many patients.

As we've learned more about cancer, researchers now realize that not all women with early breast cancer, including stage I and II, lymph node-negative breast cancer, actually benefit from adjuvant systemic therapy, which refers to chemotherapy, hormone therapy, and/or the drug Herceptin.

Not All Breast Cancer Is the Same

More researchers are now thinking that not all breast cancers should be treated the same. Through findings from breast cancer clinical trials, scientists are discovering they can do a risk analysis of each woman's particular cancer and then base their treatment upon the estimated risk of the breast cancer coming back.

Using a tool called the Recurrence Score, scientists are learning to quantify the likelihood of breast cancer recurrence in women with node-negative, estrogen receptor-positive (ER+) breast cancer and also predict the extent of chemotherapy benefit. While chemotherapy is necessary for some types of breast cancer, it may not be necessary for other types. And that's where the Oncotype DX test comes into play.

Breast Cancer and Oncotype DX

Oncotype DX is a diagnostic test that assesses the tumor tissue and estimates the likelihood that invasive breast cancer will return, or recur after treatment. By analyzing the expression pattern of certain genes in breast tumors, the Oncotype DX test can more precisely estimate a woman's risk of cancer recurrence when compared with the standard assessments doctors normally use to evaluate the risk of cancer returning.

The Oncotype DX screening test is performed on each tumor sample to get the Recurrence Score. The Oncotype DX test scores the breast tumor on 21 different genes involved in breast cancer and gives a Recurrence Score, or a number between zero and 100 that shows the chance of the breast cancer returning within 10 years of the original diagnosis.

The Recurrence Score is then categorized into one of three groups: low, intermediate, or high risk. For example, if a tumor has a Recurrence Score over 31, a high-risk score, this means there's a greater chance that the breast cancer will return. If a tumor gets a Recurrence Score of 18 or less, a low-risk score, this signals a lower chance that the breast cancer will return. If the Recurrence Score is 19 to 30 then the recurrence risk is intermediate.