If young women take certain simple steps when they are adolescents, they may reduce risk of breast cancer later in life. A research suggests that puberty could be a crucial time for development of breast cancer.

Regular exercise is believed to delay the beginning of a girl's first menstrual period. That is when the body creates hormones that stimulate the majority of breast cancers. According to a study, just 4 hours of weekly exercise can postpone hormone surges for up to 12 months.

Four hours a week is not a large amount of activity for a girl. She can play dodge ball, play on the playground or ride her bike. Because exercise can lower hormone activity, it can reduce risk of breast cancer, even after a girl starts having periods.

One more way is cutting back on fat. Girl who cut her fat intake by only 6 percent lowered her estrogen and progesterone levels by at least 30 percent, according to a study. These theories are not really well tested and need more research.

Breast cancer is the most common cancer in women, other than skin cancer. In the United States approximately 183,000 new cases are diagnosed and about 41,000 women die each year from cancer originating in the breast.