WASHINGTON — The nation’s top doctor called on Tuesday for immediate action to reduce the rate of skin cancer, the most commonly diagnosed cancer in the country and one that is often preventable.

Americans need to do more to reduce their exposure to the harmful rays of the sun and tanning beds, Dr. Boris D. Lushniak, the acting surgeon general, said in a report.

Nearly five million Americans are treated for skin cancer every year, at an average annual cost of $8.1 billion, according to the report. Over the last three decades, the number of people with skin cancer has grown higher than that of all other cancers combined, according to the report.

Each year, about 9,000 people die from melanoma, the deadliest form of skin cancer. That is a small fraction of the 160,000 people who die annually of lung cancer, but the report notes that the incidence of melanoma is on the rise. Rates of melanoma increased more than 200 percent from 1973 to 2011, and it is one of the most common cancers among teenagers and young adults, according to the report.