Four Types of Triple-Negative Breast Cancer Identified

Triple negative breast cancer subtypes defined by microRNA expression signatures

(RxWiki News) Triple-negative breast cancer is so tough to beat because there are few treatment options. Scientists have uncovered more about how triple-negative breast cancer behaves, and these findings could improve the outlook for patients.

Molecules known as microRNA can define triple-negative into one of four subtypes, according to a new study. 

In the future these molecules might screen for the disease, serve as markers to predict patient outcomes and possibly even be targets for new therapies.

"Find out exactly what kind of breast cancer you have."

Researchers at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James) collaborated with scientists in Italy.

Charles Shapiro, MD, director of Breast Medical Oncology and professor of internal medicine at the OSUCCC – James, and Kay Huebner, PhD, professor of molecular virology, immunology and medical genetics at Ohio State, were the study’s senior investigators.

"The treatment of women with triple-negative breast cancer is challenging because this malignancy can be very different genetically from one patient to another," Dr. Shapiro said in a statement. "We believe these microRNA signatures define novel subsets of triple-negative breast cancer and offer new insights into the biology of the disease and better ways to treat these patients."

MicroRNAs help to direct the inner workings of cells. MicroRNA that compose the signatures Dr. Shapiro mentioned play a role in how cells grow, proliferate and survive, as well as the movement of cells.

About 15 percent of all breast cancers are triple-negative cancers. The term triple-negative refers to the fact that these cancer cells don’t have receptors for estrogen, progesterone or HER2. As a result, this cancer doesn’t respond to therapies that block those hormones or HER2.  Furthermore, because there are no effective treatments, this cancer is extremely aggressive.

For this study, the researchers examined 59 normal, 165 tumor and 54 metastatic (cancer that has spread) tissue samples. For each sample, the scientists identified and evaluated all of the microRNA molecules and cancer-related genes.

The team compared these profiles with those found in the tumors, in nearby normal tissue and in lymph node tissue where the cancer had spread in 173 triple-negative breast cancer patients.

This research defined how microRNA works in both original and metastatic tumors. The profiling defined four molecular subclasses of triple-negative breast cancer. Two microRNA signatures were helpful in predicting overall survival in women aged 50 and younger.

The study was published in the February issue of PLOS ONE. This work was supported by United States Public Health Service, National Cancer Institute and the Stephanie Spielman Foundation for Breast Cancer Research.

Review Date: 
February 11, 2013