Researchers Learning Why Breast Cancer May be More Aggressive in Young Women (dateline August 23, 2008)
The majority of women who are diagnosed with breast cancer have already reached menopause, but for young women, those who are diagnosed tend to have more aggressive forms of the disease. Now researchers are beginning to understand why breast cancer may differ in young women. According to new research, hundreds of sets of genes are more active in young women with breast cancer compared to older women. The research could have implications for how young women are treated for breast cancer.
"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, in a Duke Comprehensive Cancer Center news release. "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."
To perform the research, Dr. Blackwell and her colleagues at Duke Comprehensive Cancer Center examined breast cancer tissue samples from nearly 800 women in five countries. They divided the samples by the women's age and found that more than 350 sets of genes that were active only in the breast cancer tissue samples from women under age 45. Interestingly, the researchers also noted that in the samples from women over age 65, these sets of genes were not active.
"The breast tumors that arose in younger women shared a common biology, and this discovery was truly remarkable," Blackwell said in the Duke news release. "The genes that regulate things like immune function, oxygen supply and mutations that we know are related to breast cancer, such as BRCA1 [breast cancer gene 1], 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."
BRCA1 (breast cancer gene 1) and BRCA2 (breast cancer gene 2), for example, are two tumor suppressor genes that, when functioning normally, help repair damage to DNA (a process that also prevents tumor development). Researchers have discovered that women who carry mutations of BRCA1 or BRCA2 are at higher risk of developing both breast and ovarian cancer than women who do not have these genetic mutations. Women with BRCA1 mutations account for about 5% of breast cancer cases.
The researchers say their study could help better understand the characteristics of breast cancer in young women and help develop targeted therapies that are more effective in treating these women. However, they note that their research did not identify any certain characteristics of breast cancer tumors in older women, which they point out is an area needing more research.
About 77% of women with breast cancer are over age 50 at the time of diagnosis. Three quarters of women with breast cancer are over age 50 at the time of diagnosis. Women between the ages of 20 and 29 account for only 0.3% of breast cancer cases.