Gene Study Yields New Clues to Breast Cancer

SUNDAY, Sept. 23 (HealthDay News) -- A comprehensive look at the genetic blueprint of breast cancer has revealed new insights into the disease -- including the discovery that certain breast and ovarian tumors may be closely related.

Basal-like breast tumors -- one of the most deadly subtypes of breast cancer -- are genetically more similar to ovarian cancer than to other breast cancers, the new research found.

In this study, the scientists used six different technologies to analyze 348 tumors from women with breast cancer. They looked for defects in DNA, RNA and proteins in the tumors.

They confirmed the existence of four main subtypes of breast cancer -- luminol A, luminal B, HER2 and basal-like -- and found unique genetic and molecular signatures within each of the subtypes.

The findings add to growing evidence suggesting that tumors should be catalogued and treated based on the genes that are disrupted rather than their location in the body, the researchers said.

"With this study, we're one giant step closer to understanding the genetic origins of the four major subtypes of breast cancer," study co-leader Dr. Matthew Ellis, chair of medical oncology at Washington University School of Medicine in St. Louis, said in a university news release.

One oncologist said the findings on breast cancer's diversity echo her own experience in treating patients.

"The diversity of breast cancer is instinctual to a practicing breast surgeon who has seen women with breast cancer, presumably the same stage, have differing outcomes with respect to recurrence and survival," said Dr. Donna-Marie Manasseh, director of breast surgery at the Maimonides Breast Cancer Center in New York City. "This research validates what we have suspected."

According to Ellis, the new study suggests that most basal-like breast tumors and ovarian tumors have similar genetic origins and potentially could be treated with the same drugs.

Basal-like tumors account for about 10 percent of all breast cancers and disproportionately affect younger and black women in the United States. Basal-like tumors include most triple-negative breast tumors, which are often aggressive and do not respond to therapies that target hormone receptors or to standard chemotherapies.

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Gene Study Yields New Clues to Breast Cancer