Analysis identifies four genetically distinct types of breast cancer

In study findings published in the journal Nature, researchers reported that they identified four genetically distinct types of breast cancer, one of which closely resembles ovarian cancer. "This is the road map for how we might cure breast cancer in the future," remarked study co-author Matthew Ellis, adding that "now we can investigate which drugs work best for patients based on the genetic profiles of their tumours."

For the study, the latest from the US Cancer Genome Atlas, researchers examined tumours from 825 patients using gene-expression-based assays. The analysis revealed that when viewed this way, breast cancers can be classified as either basal-like, luminal A or B, or HER2-enriched. "This classification has expanded our appreciation of the heterogeneity of breast cancer and has provided a way to sub-classify the disease in a manner that might have clinical utility," the researchers said.

Specifically, investigators found that the genetic derangements of basal-like cancers make them more genetically similar to ovarian cancers than to other breast cancers. Ellis said that "whether they can be treated the same way is an intriguing possibility that needs to be explored." In addition, the researchers identified at least 40 genetic alterations that might be treated with drugs, many of which are already being developed for other types of cancer that have the same mutations.

Ellis indicated that there are immediate therapeutic implications from the study, including using PARP inhibitors, which are prescribed for ovarian cancer, to treat basal-like breast cancer instead of the more commonly used anthracyclines. Researchers are also planning to study the role of Roche's Herceptin (trastuzumab) in non-HER2-enriched tumours.

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