ANI 079(Health)
Breastfeeding may help cut cancer risk
Washington, Aug 26 : Breastfeeding for 6 months or longer can reduce a woman's risk
of developing an aggressive form of breast cancer, says a new study, which explored how
reproductive factors influence different types of breast cancer.
According to the study, a woman's breastfeeding practices, age at menopause are some of
the factors that can influence her risk of developing certain types of breast cancer.
The study has been published in the October 1, 2008 issue of CANCER, a peer-reviewed
journal of the American Cancer Society.
The study's results suggest that there are distinct and separate hormonal risk factors
associated with different subtypes of breast cancer.
Clinical differences among breast cancer subtypes have been well-described, but
researchers have limited data on how the various subtypes arise and which individuals are
at greatest risk.
Having this information could help physicians identify which women are more likely to
develop certain subtypes of breast cancer, which respond differently to different
anti-cancer therapies and have very different survival rates.
Amanda Phipps, a predoctoral research associate at the Fred Hutchinson Cancer Research
Center in Seattle, and her colleagues conducted a study 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.
Some breast cancer types express one or more of these proteins on their cell surface,
while others express none. The research team suspected that reproductive or hormonal
factors may play a significant role in a woman's risk of developing different subtypes
because these cell receptors are influenced by endogenous sex hormones.
For their study, the scientists pooled two population-based studies of breast cancer in
women aged 55-79 years. Their analysis included 1,023 women with breast cancer whose cells
express the estrogen and progesterone receptors (called luminal cancers), 39 women with
HER2-overexpressing breast cancer, and 78 triple-negative cases (no expression of
estrogen, progesterone, or HER2 receptors). The study also included 1,476 women without
breast cancer.
The investigators found that reproductive risk factors varied considerably by breast
cancer subtype. For example, early age at menarche was associated with risk of
HER2-overexpressing disease but not with any other subtype.
Breastfeeding for 6 months or longer was associated with a lower risk of luminal cancer
as well as triple-negative cancer, a type that can be particularly aggressive and
difficult to treat.
Both late age at menopause and use of estrogen plus progestin hormone therapy were
associated with an increased risk of luminal disease. Finally, no differences in risks
associated with number of children or the age when a woman first gave birth were observed
by subtype.
The study authors concluded that their results indicate that "certain reproductive
factors may have a greater impact on risk of certain molecular subtypes of disease
compared to others."
They added that additional studies on the causes of breast cancer subtypes are needed
to better understand the biology of the disease.
--ANI
