Cancer causes cells to divide uncontrollably. This can result in tumors, damage to the immune system, and other impairment that can be fatal.In the United States, an estimated 15.5 million people with a history of cancer were living as of January 1, 2016, according to a 2018 report from the American Cancer Society.In this article, we examine types of cancer, how the disease develops, and the many treatments that help improve the quality of life and survival rates. Cancer causes cells to divide uncontrollably. It also prevents them from dying at the natural point in their life cycle.Genetic factors and lifestyle choices, such as smoking, can contribute to the development of the disease. Several elements affect the ways that DNA communicates with cells and directs their division and death.After nonmelanoma skin cancer, breast cancer is the most common type in the U.S. However, lung cancer is the leading cause of cancer-related death.Treatments are constantly improving. Examples of current methods include chemotherapy, radiation therapy, and surgery. Some people benefit from newer options, such as stem cell transplantation and precision medicine.