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The importance of lymph nodes: Has the cancer spread?

What Is Breast Cancer?: Page 2

By , Caring.com senior editor
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The lymphatic system carries fluid that fights infection, and the lymph nodes and vessels near the breast and under the arm are one of the first places breast cancer typically spreads. Once in the lymph nodes and vessels, cancerous cells can be carried to other areas of the body.

Doctors biopsy lymph nodes to assess if breast cancer has spread. You'll hear the term lymph node involvement as a marker for whether a cancer is contained within the breast or is metastatic, which means it's spreading to other areas. The term sentinel node refers to the lymph node that doctors determine is the first node into which a tumor might drain; this node is usually biopsied.

Breast cancer tests for diagnosis and staging

Once a mammogram, ultrasound, or MRI locates a potential tumor, the doctor may order additional tests to see if the cancer has spread:

  • Blood tests can assess kidney and liver function and may also reveal tumor markers, although these are not very reliable for breast cancer.
  • A biopsy of the tumor will be used to assess certain characteristics that can tell the doctor how aggressive the cancer is. Typically, lymph nodes are biopsied as well.
  • Chest X-rays can show if the cancer has spread to the lungs.
  • Bone scans can reveal whether there's cancer in the bones.
  • CT scans are used to look at the chest and abdomen to see if the cancer has spread to other organs.
  • Sometimes PET scans are used to check for cancer in the lymph nodes or to scan the whole body for cancer.
  • The doctor may ask for an MRI if she's concerned about whether cancer has spread to the brain.
  • The doctor will ask about the patient's family history and may recommend a new test called Oncotype DX, which is used to predict the likelihood of breast cancer recurrence. It can be a useful tool for women with early-stage cancer who are trying to decide whether chemotherapy is necessary.

How breast cancer is diagnosed and staged

Oncologists use a complex system of letters and numerals to determine the status or stage of breast cancer. Knowing these numbers is very important, because it will help the patient understand the prognosis. If your friend or relative wants you to accompany her to doctor visits, you can help her understand what you both hear there. You'll also want to know as much as possible in order to research and understand treatment options and explore clinical trials.

The letter T is used to designate the tumor size and spread, the word N indicates whether there's cancer present in the lymph nodes, and the letter M stands for metastasis. So T2, N0 (zero), M0 means a 2-centimeter tumor that has not spread to the lymph nodes or any other areas.

The medical team then combines this information into a stage. There are four stages of invasive breast cancer, and some stages are broken down still further:

Stage 1

The tumor is smaller than 2 centimeters and no lymph nodes are involved.

Stage IIA

There are three possibilities at this stage:

  • The tumor measures less than 2 centimeters but has spread to the axillary lymph nodes.
  • No tumor is found in the breast itself, but cancer cells are found in the lymph nodes under the arm.
  • The tumor is between 2 and 5 centimeters across but there's no lymph node involvement.

Stage IIB

There are two possibilities at this stage:

  • The tumor is 2 to 5 centimeters across and has spread to the axillary lymph nodes.
  • The tumor is bigger than 5 centimeters but hasn't spread to the lymph nodes.

Stage IIIA

There are two possibilities at this stage:

  • The tumor has spread to the axillary lymph nodes and the nodes are clumped together or sticking to other structures.
  • No tumor is found in the breast, but cancer is in the lymph nodes, which are clumping together or sticking to other structures, or it is present in lymph nodes near the breastbone.

Stage IIIB

There are two possibilities at this stage:

  • A tumor of any size has spread to the chest wall or skin of the breast; it also may have spread to axillary lymph nodes or those near the breastbone.
  • All inflammatory breast cancer, which is considered Stage IIIB or higher when diagnosed.

Stage IV

The cancer has spread to other organs of the body, usually the lungs, brain, or liver; or the bones. Sometimes the doctor will say the cancer is metastatic at presentation, which means it had already spread to other parts of the body before the original tumor was discovered.