Diagnosing Metastatic Breast Cancer: What the Stages Mean

Your best treatment options depend on the stage of cancer.

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Even if you don’t fully understand what cancer stages mean, you may know that a higher stage refers to a cancer that’s more serious. Determining the stage of a cancer, however, is an important and detailed process that helps assess the most appropriate treatment for the patient.

The stages of breast cancer range from I (one) to IV (four). Earlier stages typically represent a breast cancer that has not spread beyond the breast, and are thus more easily treatable.

“For all types of breast cancer, we really separate early stage, which is stage I, II, and III … versus stage IV breast cancer, which is defined as the cancer having spread to a distant organ,” says Amy Tiersten, MD, hematologist and oncologist at The Mount Sinai Hospital. 

In simplest terms, cancer stages are determined by:

  • Size of the tumor: Larger tumors are a later-stage cancer.

  • Lymph node involvement: If cancer affects lymph nodes, it is a later-stage cancer.

  • Biology: For breast cancer, the cancer stage depends on receptor status, which has a major effect on treatment options. Receptor status and other biological features of the cancer cell were added to the breast cancer staging system in 2018. 

These factors are combined to determine the overall stage and the best course of action. For earlier stages of breast cancer, the goal of treatment may be to cure the patient, often by removing the tumor via surgery for breast cancer.

On the other hand, stage IV (metastatic) breast cancer may not be curable. These are cancers that have spread throughout the body and are more aggressive. However, this does not mean that metastatic breast cancer cannot be treated.

“The role of treatment for stage IV breast cancer is to prolong life and to improve quality of life by addressing symptoms that patients have from the metastatic disease,” says Dr. Tiersten. Learn more about treatment for metastatic breast cancer here.

While cancer treatment can be intimidating, a good oncology team will “demystify” the process by explaining what to expect every step of the way, says Dr. Tiersten. “Being able to have realistic conversations about prognosis and expectations … is something that is very important.”