It is widely recognized that breast cancer mostly affects those women fifty or over. However, there is precedent for young women to develop the disease. There are a few reasons for this including:
Change in hormone levels. Younger women tend to experience widely varying hormone levels that fluctuate far more than older women, and this can put them at greater risk for breast cancer and the need for treatment.

Environmental changes such as pollution, pesticides and food contamination as well as use of antiperspirants can also have an effect. Lifestyle changes may also be considered. Another thing to think about is breast enhancement. This is usually done to increase one's self confidence and self image. However what is generally not considered it the fact that breast enhancement methods can rely on hormone manipulation or excessive hormones.

Lifestyle choices can also play apart. These include mental or emotional stress as well as poor diet and sleep patterns, smoking or eating genetically enhanced foods.

Late childbearing can also be considered as a risk factor as is lack of breast feeding. Not only does this pose a risk to the mother, it can be considered unhealthy for the baby as well, though at this time there is no conclusive proof of an increase in breast cancer risk.

In short, although the highest level of risk is still seen in older women, there is significant chance for younger women to develop the disease due to rapidly changing lifestyle choices. The best way for younger women to prevent breast cancer is to ensure rest, eat healthy, exercise and make sure that their stress level in within manageable limits.