NEW YORK — U.S. health regulators on Thursday approved Medicare coverage for lung cancer screening by low-dose CT, the first time the government health insurance program for the elderly and disabled will pay for such a program of early detection in an effort to save lives.

The decision applies to Medicare beneficiaries ages 55-77 who are current smokers or who quit within the last 15 years, and who racked up at least 30 “pack years.” The latter is possible if they smoked one pack a day for 30 years, for instance, two packs a day for 15 or three packs a day for a decade.

The coverage is effective immediately, the Centers for Medicare and Medicaid Services announced, and applies nationwide.

In a statement, CMS chief medical officer Dr. Patrick Conway called the decision to pay for a once-a-year screening “an important new Medicare preventive benefit since lung cancer is the third most common cancer and the leading cause of cancer deaths in the United States.”

The usually incurable disease will kill about 158,000 people in the U.S. this year, according to the American Cancer Society, and 221,200 cases will be diagnosed.