Scientists Create Molecular Map of Breast Cancer, Uncovering Previously Unknown Tumor Subtypes

The study was published in the journal Cell Reports Medicine. Researchers from Vanderbilt-Ingram Cancer Center in the United States combined data from more than 7,600 tumors across 22 independent studies.

To create the map, the researchers analyzed transcriptomes — collections of RNA molecules that reflect gene activity within a tumor. Using computational methods, they grouped tumors according to shared molecular characteristics, disease progression patterns, and treatment sensitivity.

The analysis showed that traditional breast cancer categories do not always capture important biological differences between tumors. In particular, some tumors with low estrogen receptor levels more closely resemble estrogen receptor-negative breast cancer than tumors typically classified as estrogen receptor-positive. This distinction could be important when selecting treatment.

The researchers also identified a previously hidden neuroendocrine subtype of breast cancer associated with less favorable outcomes following standard treatment. They identified the FGFR1 protein as a potential therapeutic target for this tumor subtype.

In addition, the map revealed subgroups of HER2-positive tumors that may be particularly dependent on the HER2 signaling pathway, as well as an aggressive subtype of triple-negative breast cancer that may be sensitive to drugs targeting specific signaling mechanisms involved in tumor growth.

The researchers also developed a tool that can classify tumors into the identified molecular subtypes using data from standard RNA sequencing. This could facilitate further research into newly identified forms of breast cancer and help identify suitable treatment approaches.

However, for now, this is a promising research tool rather than a proven method for improving treatment outcomes. The next step will be to determine whether selecting therapies based on the molecular map actually helps patients live longer and achieve better disease control.