(Ivanhoe Newswire) -- Your age at menopause and your breastfeeding
practices can influence your risk of developing certain types of breast cancer,
according to a new study.
The study at the Fred Hutchinson Cancer Research Center in Seattle was done to
better understand the specific risk factors for the subtypes of breast cancer,
which are classified by expression of the estrogen receptor, the progesterone
receptor and the HER2 receptor. The results suggest there are distinct and
separate hormonal risk factors associated with different subtypes of the
disease.
Researchers looked at data from breast cancer patients aged 55 to 79 whose cells
had either the estrogen and progesterone receptors (called luminal cancers), the
HER2 receptor or no expression of estrogen, progesterone or HER2 (triple
negative cancer).
Results show reproductive risk factors varied significantly by breast cancer
subtype. For example, having your first period at an early age was associated
with the risk of HER2 but not with any other subtype. Breastfeeding for six
months or longer was associated with a lower risk of luminal cancer as well as
triple-negative cancer. Finally, going through menopause at a late age and
taking estrogen plus progestin hormone therapy were both associated with an
increased risk of luminal cancer. There were no differences in the subtypes as
far as the risks associated with number of children or the age when a woman
first gave birth.
The authors say more studies on the causes of breast cancer subtypes are needed
to better understand the biology of the disease.
SOURCE: CANCER, published online August 25, 2008
