The rate of U.S. diagnoses for melanoma, the deadliest form of skin cancer, has doubled in the past 30 years, from 11.2 cases per 100,000 people in 1982 to 22.7 cases per 100,000 in 2011, according to a Centers for Disease Control and Prevention study released June 2. As a result, the agency expects the cost of melanoma care to nearly triple, from $457 million in 2011 to $1.6 billion in 2030.