New Breast Cancer Staging System Incorporates HER2 Status to Better Assess Prognosis

By Stephanie Murg, Managing Director, G2 Intelligence

A new breast cancer staging system adds HER2 (ERBB2-positive disease) status to a list of factors used to assess prognosis in women who undergo neoadjuvant (pre-surgical) therapy for the disease. The “Neo-Bioscore” staging system, which is described in a validation study published March 17 in the online edition of JAMA Oncology, refines a previous clinical-pathologic scoring system and emphasizes the importance of tumor biology as a critical prognostic indicator.

Both the new system and its predecessor, known as CPS+EG, were developed by researchers at the University of Texas MD Anderson Cancer Center in Houston. CPS+EG, which incorporates preclinical stage (CS), estrogen receptor status (E), grade (G), and post-treatment pathologic stage (PS), 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.

For this new retrospective study, the researchers evaluated 2,377 MD Anderson breast cancer patients with non-metastatic invasive breast cancer that had been treated with neoadjuvant chemotherapy followed by local therapy. A CPS+EG score was determined for each patient, with HER-2 status added to the model. The novel staging system, Neo-Bioscore, was constructed by adding a point to the CPS+EG score for HER2-negative tumors.

The researchers found that the new cohort validated previous findings: CPS+EG score improved prognostication of patients. They also discovered that when the Neo-Bioscore was applied, there was a shift from the previous CPS+EG scoring, meaning it resulted in more refined stratification in 1,786 (75 percent) of patients. This shift reflects the number of HER2-negative tumors in the study. Also, when adding HER2, the improvement was highly significant.

“With this tool, I can give my patients the precise information they are looking for—a more refined prognosis,” says Elizabeth Mittendorf, M.D., Ph.D., associate professor of breast surgical oncology at MD Anderson and first author of the study. “Also, with this data, we will know which patients are in greatest need of additional therapy. Hopefully these findings will result in more informed conversations between doctor and patient.”