Oncotype DX®

Is Testing Right for Me? I Have My Test Results

Oncotype DX®

Breast Tumor Characteristics

Breast and lymph node tissue removed during surgery is studied in the lab for clues about how aggressive and advanced the breast cancer is. These clues are called pathology variables. In addition to the stage of the breast cancer, doctors also get other information that helps guide what treatments may be best from these pathology variables. The main variables are explained below. Oncotype DX is one more pathology variable that may give you and your doctor extra information about your specific tumor.

Tumor Grade
Hormone Receptors (ER/PRs)
HER2/neu Receptor Status
Recurrence Score®

Tumor Grade

The grade of a tumor classifies how tumor cells divide, grow and spread to other areas. Tumor grade reflects how aggressive tumor cells are.

Tumor grades range from one to three. A Grade 1 tumor is the least aggressive type of tumor. They appear most 'normal' under the microscope. This is called differentiated. A Grade 3 tumor is the most aggressive type of tumor. It is also the most 'abnormal' appearing and least differentiated. A Grade 2 tumor falls somewhere in between.

Hormone Receptors (ER/PRs)

Hormones stimulate certain tissues, like breast tissue, to grow. Cells control what hormones can affect them through cell receptors. Cell receptors only recognize specific hormones, much like a key fitting into a lock. Normal breast tissue has many receptors for estrogen and progesterone, often called ER (Estrogen Receptors) and PR (Progesterone Receptors) for short.

When a cell becomes cancerous, it changes how the cell works.  Breast cancer cells may lose their normal hormone receptors. When this happens, cancer cells are unable to recognize estrogen and progesterone. The key has lost its matching lock. This is called hormone negative cancer or ER/PR-.

Breast cancers that keep their hormone receptors are called hormone positive, or ER/PR+. About 50 to 70% of all breast cancers are ER/PR+. The difference between ER/PR+ and ER/PR- cancer is important for deciding on the best treatment. Oncotype DX® testing is specifically for ER/PR+ tumors.

HER2/neu Receptor Status

The Human Epidermal growth factor Receptor (HER2/neu or just Her2) is a cell receptor gene that is on normal breast cells. However, on some breast cancer cells, the receptor can multiply. This is called gene amplification and is known as 'HER2+' breast cancer. About 20% to 40% of breast tumors are HER2+, with half showing very high levels of amplification.

The HER2 gene normally controls growth and cell damage repair. When the gene amplifies, it causes out-of-control cell growth. In general, HER2+ cancers multiply faster and are more aggressive than tumors that are not.

While HER2+ tumors tend to recur, they are also more likely to respond to certain types of treatment. Thirty-five percent of these tumors will respond to a drug called Herceptin (trastuzumab). This drug targets the HER2 receptor and blocks it, preventing growth. HER2 amplification is also important in predicting how well women respond to different types of hormonal therapy and chemotherapy.

Medical guidelines generally agree that Oncotype DX testing is useful for patients with early stage, node negative, hormone positive breast cancer. Where there lacks agreement is HER2 status. ASCO guidelines make no mention of HER2 status. National Comprehensive Cancer Network (NCCN) guidelines limit the use of Oncotype DX to HER2 negative tumors. However, very small HER2+ tumors are allowed. NCCN bases its position on the fact that Herceptin therapy is medically necessary for HER2+ cancers bigger than 1cm.

Recurrence Score®

The Recurrence Score® from Oncotype DX testing supplements standard pathology. Studies show that the Oncotype DX test is actually more accurate at predicting cancer recurrence than standard pathology alone. Standard variables were found to be not as consistent or reliable.

Tumor size is a standard pathology variable that we'll use as an example. In general, larger tumors have a greater chance of cancer returning. Interestingly, some studies found that 1/3 of small tumors actually fell into the high-risk category on Oncotype DX.

The Recurrence Score adds important information about a tumor's biology. Adding this information to a standard pathology work-up increases overall understanding to guide diagnosis and treatment. Patients and doctors have more information to help them make personalized treatment decisions.

Next: Resources