Breast cancer is quite different from most cancers in that we actually know about one possible cause. It is a specific genetic mutation in a gene called BRCA (for breast cancer gene). There are two known forms of the BRCA genes: BRCA1 and BRCA2.

BRCA Genes & Cancer Risk
BRCA genes present: 36% - 85% risk
BRCA genes not present: 13% risk

Those of us who carry one or the other of these genes have a chance of developing breast cancer that falls between 36% and 85%, depending on the studies you consult. Compare that to the approximately 13% risk carried by those without a mutation, and you can see the damage these genes can do.

In addition, those of us who carry a BRCA gene and do get breast cancer have an increased risk of developing it in the other breast later on. We also have an increased risk of developing ovarian cancer in addition to, or instead of, breast cancer. Men who carry a BRCA gene also have a greater risk of developing breast cancer, compared to men without the gene.

The up side is that only 5% to 10% of breast cancers are due to these genes, meaning that it's not that widespread in the population. If you suspect your family may be in that unlucky minority, however, it's in your best interests to consider availing yourself of the tests available that can detect the altered genes.

Know your risk

For most of us, however, our risk of developing breast cancer can't be pinned to a specific, known gene. Instead, we're stuck never quite knowing what combination of factors is going to either doom or protect us.Here are some of the main risk factors for the development of breast cancer:

Age-based risks

• The risk of cancer increases with each decade of life
• A menstrual cycle that began before age 12
• Menopause that began after age 55
• Having your first child after age 30.

Lifestyle and diet-based risks

• Smoking
• Drinking alcohol
• Eating a diet high in fat
• Obesity

Medical history related risks

• Using hormones, estrogen and progesterone used in birth control pills or hormone replacement therapy.
• Having a family history of cancer
• Prior radiation treatment to the breast or chest
• A history of breast cancer or benign breast disease in one breast.

See also

• Breast cancer - introduction
• Breast cancer - prevalence
• Breast cancer - prevention
• Breast cancer - detection and diagnosis
• Breast cancer - prognosis
• Breast cancer - treatment options
• Breast cancer - dealing with the aftermath
• Building a support network