The Centers for Disease Control and Prevention says breast cancer is the second most common cancer among women in the United States. BreastCancer.org estimates that 276,000 new cases of invasive breast cancer and around 49,000 non-invasive cases are expected in 2020 in the United States. The Canadian Cancer Society says breast cancer is the most commonly diagnosed cancer among Canadian women, and the second most commonly diagnosed cancer in the country.
Breast cancer treatment depends on the stage of the cancer, personal choices as well as doctor recommendations. Other factors like preexisting conditions or health history also may play a role in determining patients' treatments. In many cases, chemotherapy is included in a treatment plan. Chemotherapy targets fast-growing cancer cells in the body to prevent cancer from spreading and to shrink tumors. However, the American Cancer Society says other normal cells that are fast-growing can be affected by chemotherapy and cause side effects. These cells include blood-forming cells in bone marrow, hair follicles, cells in the mouth, digestive tract cells, and reproductive system cells. This is why many people lose their hair during chemotherapy treatments.