Most of the few risk factors that we know about each contribute only a small amount to the risk of developing breast cancer. The table  below shows associated with each.

Another woman could have none of the known risk factors, yet she might develop breast cancer next year. In addition, many of the known breast cancer risk factors are characteristics that women cannot change or eliminate from their lives. For instance, the later a woman reaches menopause, the higher her risk of breast cancer. Unfortunately, women have no control over the age at which they stop menstruating.

There are a few known breast cancer risk factors that women do have some control over, including alcohol consumption. However, we cannot simply recommend that women cut these risk factors out of their lives because we do not know what effect this recommendation would have on women's total health. For instance, some evidence indicates that alcohol consumption may lower the risk of heart disease, and this disease kills more women each year than breast cancer.

Some organizations have tried to promote simple messages about risk factors. Women are told that they can prevent breast cancer by following special diets and avoiding certain exposures. But the study of risk factors is complex, and women need to understand this complexity.

Our current knowledge of risk factors is of limited use to individual women. If we want to help individual women, we need to find something that is guaranteed to prevent every woman from ever getting breast cancer, and that does not increase the risk of other illnesses. So far, we have not found a real prevention for breast cancer.

Age and Breast Cancer Risk
Women age 50 and older have a large relative risk for breast cancer when compared to women under the age of 50. This is because most breast cancers occur in women ages 50 and older -- about 77%. In general, breast cancer risk increases with age. These days, many news stories about breast cancer focus on young women who get breast cancer, giving the impression that breast cancer in young women occurs more often now than it did in past years. In reality, the incidence rate of breast cancer in women under 40 has remained about the same for the last 25 years. The table below shows the estimated number of breast cancer cases that were diagnosed in 2001 for each age group of women.