Triple-negative breast cancer is a particularly aggressive subtype of the disease that does not depend on the hormone estrogen to grow and spread, researchers explain. This type of cancer, which accounts for 10 to 20 percent of all breast cancers, does not respond to many breast cancer therapies, such as the hormone-blocking drug Tamoxifen.
The observational study involved more than 1,900 women between the ages of 20 and 44, including more than 1,000 with a history of breast cancer. Reproductive histories among the women were compared to determine how childbirth affected premenopausal breast cancer risk.
Researchers say their study is the first to look at how childbirth affects breast cancer risk among premenopausal women, who have a higher risk of more aggressive breast cancer subtypes. The study also confirmed that breast feeding also has a protective effect against triple-negative breast cancer. However, other studies have shown that having three or more children raisesa woman's risk of triple-negative breast cancer.
Childbirth and breast feeding also reduce the risk of the most common breast-cancer subtype, ER positive, previous studies have found.
Researchers say these new results could be particularly impactful for African-American women, who experience higher rates of triple-negative cancer and also face worse survival outcomes. Between 2001 and 2007, the five-year relative survival rate for white women with breast cancer was 90 percent, while for black women it was only 77 percent, due perhaps to a lack of screenings or access to health care.
Compared to older women, women under 40 with breast cancer generally face more aggressive forms of the disease, higher rates of recurrence, and lower survival rates. However, progress has been made recently in the fight to find effective treatments for aggressive breast cancer in young women.
Republished with permission from EverydayHealth.com ©