New Breast Cancer Staging System Incorporates HER2 Status

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The stage of a breast cancer is often given as a number on a scale of 0 through IV. Stage 0 describes non-invasive cancer that remains in its original location, and stage IV describes invasive cancer that has spread outside the breast to other parts of the body.

This cancer staging has traditionally been based on four characteristics:

  • the size of the cancer
  • whether the cancer is invasive or non-invasive
  • whether there is cancer in the lymph nodes
  • whether the cancer has spread to other parts of the body beyond the breast

Another cancer staging system sometimes used by doctors is called TNM (tumor, node, metastasis). TNM information is sometimes required by clinical trials. The TNM system is based on three characteristics:

  • size (T stands for tumor)
    • TX means the tumor can’t be measured or found
    • T0 means there isn’t any evidence of the primary tumor
    • Tis means the cancer is in situ or non-invasive
    • T1, T2, T3, T4: the numbers are based on the size of the tumor and how much it has grown into healthy tissue; the larger the number, the bigger the tumor and/or the more it has grown into tissue
  • lymph node involvement (N stands for node)
    • NX means the nearby lymph nodes can’t be measured or found
    • N0 means the nearby lymph nodes don’t have cancer in them
    • N1, N2, N3: the numbers are based on the number of lymph nodes with cancer in them and how much cancer is found in each node; the larger the number, the more lymph nodes are involved
  • whether the cancer has metastasized (M stands for metastasis), or moved beyond the breast to other parts of the body
    • MX means metastasis can’t be measured or found
    • M0 means there is no distant metastasis (cancer spreading to a part of the body away from the breast, such as the liver or bones)
    • M1 means there is distant metastasis

Researchers at the University of Texas MD Anderson Cancer Center have developed a new breast cancer staging system that incorporates the biology of the cancer, which they say is an important indicator of prognosis for women having treatment before breast cancer surgery (doctors call treatments given before surgery neoadjuvant treatments).

Most neoadjuvant treatments involve one or more chemotherapy medicines. Targeted therapy medicines, hormonal therapy, or radiation therapy also are sometimes used as neoadjuvant treatments.

Treatment before surgery isn’t routinely used to treat early-stage breast cancer, but may be used if the cancer is large or aggressive.

The research was published online on March 17, 2016 by JAMA Oncology. Read the abstract of “The Neo-Bioscore Update for Staging Breast Cancer Treated with Neoadjuvant Chemotherapy: Incorporation of Prognostic Biologic Factors Into Staging After Treatment.”

The new staging system, called the Neo Bioscore system, builds on the CPS+EG staging system, also developed at MD Anderson. The CPS+EG staging system uses the clinical stage of the cancer before neoadjuvant chemotherapy treatment and the pathologic stage of the cancer after neoadjuvant treatment (the CPS score), as well as the estrogen-receptor status and the cancer grade to calculate a score that helps doctors estimate 5-year distant metastasis-free survival.

The Neo-Bioscore staging system adds HER2 status to the factors considered.

"The CPS+EG system predated the routine use of trastuzumab (Herceptin) in the neoadjuvant setting, so the staging system was limited by its inability to provide prognostic information for HER2-positive patients," said Elizabeth Mittendorf, M.D., associate professor of breast surgical oncology at MD Anderson, who was corresponding author of the study. "Our initial study found that if we incorporate the clinical and pathologic stage, then we can have more refined stratification of patients' prognosis. We also found that biological factors, such as estrogen-receptor status and grade, were important."

"This new staging system, Neo-Bioscore, which adds HER2 status, is another piece of the puzzle showing that the biology of breast cancer, with respect to prognosis, is critically important," said Kelly Hunt, M.D., professor and chair, ad interim, of the Department of Breast Surgical Oncology, and also a corresponding author on the study.

To develop the staging system, the researchers looked at the records of 2,377 women treated for breast cancer at MD Anderson. All the women had been diagnosed with invasive disease that wasn’t metastatic, and all were treated with neoadjuvant chemotherapy. Women diagnosed with HER2-positive disease also were treated with Herceptin.

None of these women were included in the development of validation of the original CPS+EG staging system.

After neoadjuvant treatment, all the women had either lumpectomy plus radiation or mastectomy with or without radiation.

The researchers calculated a CPS+EG score for each woman and then incorporated HER2 status by adding a point to the CPS+EG score for HER2-negative cancers. This was the Neo-Bioscore. There were eight distinct Neo-Bioscore stages. The researchers said this allowed for a more precise classification of cancer stage for 75% of the women in the study.

"I would highlight that this is a very timely subject as the AJCC [American Joint Committee on Cancer] is currently revising the breast cancer staging system," Dr. Mittendorf said in an interview. "A number of studies from our group, to include this paper in JAMA Oncology, support the inclusion of biologic factors into that staging system."

If you’ve been diagnosed with breast cancer and will have neoadjuvant treatment, you may want to talk to your doctor about this study and ask if calculating a Neo-Bioscore would help refine your prognosis.

After your diagnosis, you and your doctor will develop a treatment plan that will likely include chemotherapy and possibly targeted therapy medicines. No matter which treatments are recommended for you, you may want to talk to your doctor about:

  • why each treatment is recommended (including any combinations)
  • treatment timing and sequence
  • the expected benefits, risks, and side effects of each treatment

For more information on neoadjuvant chemotherapy, visit the Breastcancer.org Chemotherapy section.



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