Medicare Part B provides 80% coverage for most outpatient services. Among the many illnesses and conditions covered, cancer is a disease which most Americans want to insure against. Medicare’s cancer coverage is thorough and will pay for treatment for most types of cancer. However, the insured individual is responsible for 20% of the cost of the most common treatments, such as chemotherapy and radiation. For this reason, many people purchase a medicare supplement to help them pay this share of their treatment costs.