Breast cancer refers to cancer that starts in any tissue that makes up the breast. The most common site for breast cancer to develop in women is in the ducts, which carry milk. Breast cancer can also develop in the lobules which is the site where milk is produced in women. The breast is also made up of fat and connective tissue, lymph nodes, and blood vessels.
While men have some breast tissue, they have few to no lobules and much lower levels of hormones so their breast duct cells are less developed. This means they have a lower chance to develop breast cancer. When it does occur, it is commonly referred to as “male breast cancer.”
Breast cancer makes up 14% of all new cancers diagnosed each year. It is the second most common cancer among women in the US, after skin cancer.
Approximately 1 in 8 women (12.5%) will develop breast cancer in their lifetime.
While breast cancer can also develop in men, the chances that a man will develop this cancer in his lifetime is approximately 1 in 1,000 (~0.1%).
Mutations are rare, but when they exist, they significantly increase cancer risk.
In general, Caucasian women have a higher risk of developing breast cancer than African American, Hispanic, and Asian women. However, African American women develop breast cancers that tend to be more aggressive. Researchers are still investigating why this is the case.
Especially if the breast cancer in the family was diagnosed at a young age (before menopause), or in a first-degree relative (parent, sibling or child).
Exposure to certain substances, such as excessive amounts of alcohol, and hormone therapy with combined estrogen and progesterone for more than five years, are known to slightly increase the risk of breast cancer.
Many factors can decrease the risk of breast cancer, such as high activity levels, lower body mass index (BMI), giving birth for the first time at an early age, and breastfeeding.
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