Dr. Laura Witherspoon Surgeon and Medical Director, Erlanger Center for Breast Health
What Causes Breast Cancer?
Genes. We’ve all got ’em. Every cell in our bodies contains genes, which are what make us each so unique. Unfortunately, sometimes genes develop mutations, which can increase the risk of certain diseases, including breast cancer. “Mutations are alterations in a gene
that cause it to malfunction or not function,” explains Dr. Laura Witherspoon, medical director for Erlanger’s Center for Breast Health.
Breast cancer is caused by one of two gene mutations: Acquired mutation or inherited mutation.
Over 85% of breast cancer cases are caused by acquired mutations, which means a woman’s cells have changed over the course of her lifetime due to age or other factors. This mutation is NOT genetic. “Acquired mutations only affect the person who has the mutation, and those mutations are not passed down to children,” Dr. Witherspoon explains. Researchers believe radiation exposure and contact with cancer-causing chemicals contribute to acquired gene mutations, but specific causes are mostly unknown.
While rarer, as much as 10% of all breast cancer cases are related to an inherited mutation. These mutations run in families and drastically increase the chances of developing breast cancer. The most common type of inherited mutation occurs in the tumor-suppressant BRCA (BReast CAncer) genes, which include BRCA1 and BRCA2. Dr. Washburn explains, “BRCA1 and BRCA2 are normal genes we all have, but in some people these genes are mutated, and this drastically increases the risk of certain cancers. These genes are designed to maintain cell growth, but when they don’t function properly, cells have the potential for unchecked growth – the definition of cancer.”
Even if you do have a BRCA1/2 mutation though, breast cancer isn’t necessarily guaranteed in your future. BRCA1 carriers have a 55-65% chance of developing breast cancer by age 70, and BRCA2 carriers have a 45% chance of developing breast cancer by age 70.
In addition to genetic mutations, certain other factors can put a woman at increased risk for developing breast cancer. Age is one, as most breast cancers are diagnosed after age 50. Another is the density of your breasts; lots of connective tissue can make it difficult to identify tumors. Family history of the disease is a red flag, as is a personal history of the disease – if you’ve had it once, you are more likely to develop it again. An unhealthy lifestyle, which can manifest in the way of being overweight, not exercising, drinking too much, or smoking, increases your risk too. And lastly, the length of exposure to hormones can affect your chances; women who start their periods before age 12 or start menopause after age 55 are at an increased risk, since they are exposed to hormones for longer periods of time.