Breast cancer

Breast cancer is cancer of breast tissue. Worldwide, it is the most common form of cancer in females, affecting approximately 10% of all women at some stage of their life in the Western world. Although significant efforts are made to achieve early detection and effective treatment, about 20% of all women with breast cancer will die from the disease, and it is the second most common cause of cancer deaths in women.

Risk factors for breast cancer include the following:

Older age.
Menstruating at an early age.
Older age at first birth or never having given birth.
A personal history of breast cancer or benign (noncancer) breast disease.
A mother or sister with breast cancer.
Treatment with radiation therapy to the breast/chest.
Breast tissue that is dense on a mammogram.
Taking hormones such as estrogen and progesterone.
Drinking alcoholic beverages.
Being white.

      The risk of getting breast cancer increases with age. For a woman who lives to the age of 90 the odds of getting breast cancer her entire lifetime is about 12.5% or 1 in 8. Men can also develop breast cancer, but their risk is less than 1 in 1000 (see sex and illness). This risk is modified by many different factors. In a very small (~ 5%) proportion of breast cancer cases, there is a strong inherited familial risk. Some racial groups have a higher risk of developing breast cancer - notably, women of European and African descent have been noted to have a higher rate of breast cancer than women of Asian origin. However, these apparent racial differences diminish when geography is altered, as Asian women migrating to the western world, gradually acquire risk approaching that of western women.

      Other established risk factors include not having children, delaying first childbirth, not breastfeeding, early menarche (the first menstrual period), late menopause, obesity and taking hormone replacement therapy.

      The probability of breast cancer rises with age but breast cancer tends to be more aggressive when it occurs in younger women. One type of breast cancer that is especially aggressive and disproportionately occurs in younger women is inflammatory breast cancer. It is initially staged as Stage IIIb or Stage IV. It also is unique because it often does not present with a lump so that it often is not detected by mammography or ultrasound. It presents with the signs and symptoms of a breast infection like mastitis.

      Two genes, BRCA1 and BRCA2, have been linked to the rare familial form of breast cancer. Women in families expressing mutations in these genes have a much higher risk of developing breast cancer than women who do not. Together with Li-Fraumeni syndrome (p53 mutations), these genetic aberrations determine around 5% of all breast cancer cases, suggesting that the remainder is sporadic. Genetic counseling and genetic testing should be considered for families who may carry a hereditary form of cancer.