The reason why breast cancers in young women are more aggressive than those of older women has been uncovered by researchers at Duke University Medical Center.
The researchers found that unique genomic traits that young women share might be the reason for this phenomenon.
The finding, the boffins say, is important as it may help develop better and more targeting therapies.
"Clinicians have long noted that the breast cancers we see in women under the age of 45 tend to respond less well to treatment and have higher recurrence rates than the disease we see in older women, particularly those over the age of 65," said Kimberly Blackwell, M.D., a breast oncologist at Duke and senior investigator on the study.
"Now we're really understanding why this is the case, and by understanding this, we may be able to develop better and more targeted therapies to treat these younger women."
As a part of the study the researchers looked at samples of nearly 800 breast tumours from women in five countries on three continents, and divided them into age-specific cohorts.
They found more than 350 sets of genes that were active only in the tumours from women under age 45. Conversely, they found that in women over age 65 did not share these activated gene sets.
"The breast tumors that arose in younger women shared a common biology, and this discovery was truly remarkable. The genes that regulate things like immune function, oxygen supply and mutations that we know are related to breast cancer, such as BRCA1, were preferentially expressed in the tumors taken from younger women, but when we compared younger women's tumors to older women's tumors, we found those same gene sets were not expressed in the 'older' tumors," Blackwell said.
"Many of the gene sets we saw in 'younger' tumors distinguished these cancers from 'older' tumors but the reverse was not true -- there was nothing we saw in the older women's tumors that set them apart genomically.
"Identifying these distinguishing characteristics may be the first step in developing more effective treatments for these younger patients," she added.
Funded by the National Cancer Institute, the results of the study appear in the July 10 Journal of Clinical Oncology.