Breast cancer is one of the most common cancers among American women. Over 250,000 women in the United States will be diagnosed with breast cancer this year. Breast cancer often starts in glands or ducts that produce and store milk in the breasts. Physically, the condition usually manifests as lumps in the breast. If left unchecked, breast cancer can spread to other parts of the body through blood vessels or lymph nodes. Understanding where cancer comes from and why it happens can greatly improve chances for remission and recovery.
All cancers, including breast cancer, are caused by gene mutations or variations—errors—in a cell’s DNA. Most mutations are common and most often harmless. However, mutations in oncogenes or tumor suppression genes can cause cells to begin growing and dividing rapidly, leading to the formation of a tumor. Oncogenes are much like a gas pedal in that they determine how quickly or slowly the cell will grow. Tumor suppression genes are the body’s natural defense against cancer. They prevent cancer by repairing mistakes in the DNA, telling the cell when it is time to divide, and telling the cells when it is time to naturally die. A common tumor suppressing gene that can cause breast cancer when mutated is the BRCA gene. An example of an oncogene is EGFR. Understanding the mutations a patient has allows oncologists to customize a breast cancer patient’s treatments.