Advanced Breast Cancer

Monitoring your cancer

With advanced breast cancer, tracking how your disease responds to treatment is an important part of the overall care plan. To monitor your cancer, you will undergo routine testing. If that testing shows that your treatment is not slowing or stopping the growth of your cancer, you and your health care team will begin to consider alternative treatment options.

Several different tests help monitor the response to treatment in addition to your symptoms and physical examination. Often, more than one test is needed to determine how well treatment is working. These tests include imaging studies, tumor marker testing and a blood test that measures a special type of tumor cell in the blood. To have a baseline for comparison with later studies, your doctor will perform one or more of these studies before treatment begins.

You will probably have routine visits with your doctor during treatment. Use these visits to tell your doctor about any new or changing symptoms. Pain relief, easier breathing or increased energy could all be signs that the cancer is responding to treatment. Depending on the sites of metastasis, your doctor may be able to tell if treatment is working by performing a physical exam. For example, if a lymph node is a site of metastasis, your doctor may be able to feel that the node has gotten smaller, which means that the metastasis has shrunk.

Together, a physical examination and the results of ongoing, specific testing can tell you and your doctor how well your treatment is working.

Imaging studies

Many imaging studies can help your doctor monitor the response of advanced breast cancer to treatment. Imaging studies are typically done about eight to 12 weeks after treatment starts. These studies enable your doctor to measure the size of a tumor or metastatic site. A tumor or metastatic lesion that is smaller than it was before treatment is one sign that your cancer is responding to treatment.

Imaging studies that you may have include bone scans, X-rays, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). Your doctor will choose which imaging study to do on the basis of the location and extent of the metastasis. Imaging studies typically cause few or no side effects.

Bone scan

Bone scans are used to determine the extent of bone metastasis. Before the scan, a small amount of a radioactive substance is injected into a vein in your arm. Then, the radioactive substance collects in areas of metastasis in the bone. The bone scan includes a special camera that shows where the radioactive material has collected, which indicates where the cancer is. Most of the radioactive substance will be eliminated from your body within one day, and it should be completely gone within two days. Except for the brief discomfort of the needle for the injection, a bone scan is painless.

X-ray

X-rays are used primarily to monitor metastatic lesions in the lungs and bones. X-rays may be useful for detecting lesions elsewhere in the body, but other imaging studies may be needed to confirm the presence of a lesion. X-rays are painless.

CT

CT is a specialized X-ray technique that provides cross-sectional images of internal organs. CT can be used to monitor metastatic lesions in the lungs, bones or liver. During the procedure, you will lie on a table that moves slowly through the CT scanner. Sometimes, a contrast material is injected into a vein in your arm before the scan to enhance the quality of the images. CT is painless and typically takes about 30 minutes.

MRI

MRI uses radio waves and strong magnets linked to a computer to produce images of the body. MRI is valuable for viewing the spine and spinal cord. For an MRI, you lie still on a table within a long, narrow tube. If you’re claustrophobic (have a fear of closed-in spaces), tell your doctor, who may prescribe medication to decrease anxiety. Talk to the MRI technologist about any concerns you have. The machine will make loud, repetitive clicking noises during the procedure. As with a CT scan, contrast material may be injected into a vein before the procedure to enhance the images. An MRI may take up to an hour and is painless.

PET scan

A PET scan is a specialized imaging exam in which a small amount of radioactive material (tracer) is injected into a vein. The amount of radioactivity in the tracer is very low. Breast cancer cells absorb more of the tracer than regular cells do. A special camera in the PET scanner finds where the tracer collects, which shows your doctor where metastases are. The camera also takes images of the areas of metastasis. PET scans are usually not routine, but they may be beneficial if the results of other imaging studies are inconclusive. PET scans are often done at the same time as CT scans. Having both scans at the same time is known as PET/CT. You may feel a sting when you receive the tracer, but the PET scan itself is painless. PET scans of the breast often take about an hour and a half.

Tumor markers

In addition to ER, PR and HER2 tests performed on tumor tissue, cancer antigens measured in the blood are other types of tumor markers (see Table 1). Cancer antigens are proteins given off by cancer cells. Measuring the amount of cancer antigens in your blood may provide information about how many cancer cells are in your body and how it is changing over time, making it a useful tool for monitoring response to treatment. The three cancer antigens associated with metastatic breast cancer are cancer antigen (CA) 15-3, CA 27.29 and carcinoembryonic antigen (CEA). These three antigens are found in many women with metastatic breast cancer. The results of cancer antigen tests are not definitive. Low levels of an antigen do not necessarily mean that cancer is responding to treatment, and high levels may be a sign of a condition other than cancer. Because of this, experts agree that tumor markers should not be used alone to monitor the response of cancer to treatment. Instead, tumor markers should be used in combination with imaging studies.

Monitoring CA 15-3, CA 27-29 and CEA is usually done prior to treatment and periodically after treatment starts. Before that, levels can be falsely elevated. Tumor marker testing is done on a small sample of blood drawn from a vein (usually in the arm).

Table 1. Markers that aid in the management of metastatic breast cancer

Tumor marker Testing sample Description
Estrogen receptor/ progesterone receptor (ER/PR) Tissue Identifies tumors most (and least) likely to respond to hormone therapy
HER2 antigen Tissue Identifies tumors most and least likely to respond to specific HER2-targeting drugs
CA 15-3, CA 27.29 and CEA Blood Rising levels tend to indicate progression of disease
Circulating tumor cells (CTC) Blood Predict survival and assess response to therapy
 

Circulating tumor cells

Circulating tumor cell (CTC) testing can help determine prognosis and monitor response to treatment when used with imaging studies and other tests. A CTC test may also be referred to as a liquid biopsy (see Figure 1). CTCs are cells that break away from a tumor and enter the bloodstream. The test measures the number of CTCs in the bloodstream. To perform a CTC test, your doctor takes a sample of your blood and then places it in a special device. Studies have shown that the number of CTCs in the blood correlates to progression-free survival and overall survival. Knowing your CTC count can help you and your doctors make a more informed decision about your care.

It may be several weeks or months before imaging studies can detect response to treatment. Tumor marker levels are usually first determined about three to four months after treatment starts. Although the CTC test alone cannot be used to determine response to treatment, CTC counts can give your doctors an early indication of how you are doing and should be used with imaging studies and other clinical markers.

Figure 1

Talk to your medical team

No single test provides the complete picture of how your cancer is responding to treatment. Your medical team will work with you to determine the kind of testing that is best for you and how often it should be done. If you experience symptoms before your next scheduled test, alert your medical team right away.

 

Questions to ask your medical team about testing

  • Which tests will you use to monitor response to treatment?
  • How often will testing be done?
  • Is there anything I need to do to prepare for testing?
  • How long will each test take?
  • How long does it take for the results to be ready?
  • How are the results of these tests interpreted?
  • Does anything interfere with getting an accurate result with these tests?

Additional Resources

 

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