Breastfeeding

Breastfeeding

Some studies suggest that breastfeeding may slightly lower breast cancer risk, especially
if breastfeeding is continued for 1½ to 2 years. But this has been a difficult area to study,
especially in countries such as the United States, where breastfeeding for this long is
uncommon.
One explanation for this possible effect may be that breastfeeding reduces a woman's
total number of lifetime menstrual cycles (similar to starting menstrual periods at a later
age or going through early menopause).
Alcohol
The use of alcohol is clearly linked to an increased risk of developing breast cancer. The
risk increases with the amount of alcohol consumed. Compared with non-drinkers,
women who consume 1 alcoholic drink a day have a very small increase in risk. Those
who have 2 to 5 drinks daily have about 1½ times the risk of women who don’t drink
alcohol. Excessive alcohol use is also known to increase the risk of developing several
other types of cancer.
Being overweight or obese
Being overweight or obese after menopause increases breast cancer risk. Before
menopause your ovaries produce most of your estrogen, and fat tissue produces a small
amount of estrogen. After menopause (when the ovaries stop making estrogen), most of a
woman's estrogen comes from fat tissue. Having more fat tissue after menopause can
increase your chance of getting breast cancer by raising estrogen levels. Also, women
who are overweight tend to have higher blood insulin levels. Higher insulin levels have
also been linked to some cancers, including breast cancer.
But the connection between weight and breast cancer risk is complex. For example, the
risk appears to be increased for women who gained weight as an adult but may not be
increased among those who have been overweight since childhood. Also, excess fat in the
waist area may affect risk more than the same amount of fat in the hips and thighs.
Researchers believe that fat cells in various parts of the body have subtle differences that
may explain this.