WASHINGTON — Medicare may soon pay for scans to detect lung cancer in certain current or former heavy smokers.

The Centers for Medicare and Medicaid Services on Monday issued a long-awaited proposal to begin covering the screening for beneficiaries whose doctors agree meet the criteria.

A major study found low-dose CT scans of the lungs of people at especially high risk could cut their chances of dying from lung cancer by 20 percent. Last December, the U.S. Preventive Services Task Force recommended the test for certain people who smoked a pack of cigarettes a day for 30 years, or the equivalent.

Medicare had to decide separately whether to cover the screening. A final decision is due in February.