CHICAGO — Anti-smoking measures have saved roughly 8 million U.S. lives since a landmark 1964 report linking smoking and disease, a study estimates, yet the nation’s top disease detective says dozens of other countries do a better job on several efforts to cut tobacco use.

The study and comments were published online Tuesday in the Journal of the American Medical Association. This week’s issue commemorates the 50th anniversary of the surgeon general report credited with raising alarms about the dangers of smoking.

In one study, researchers used national health surveys and death rates to calculate how many deaths might have occurred since 1964 if Americans’ smoking habits and related deaths had continued at a pace in place before the report.

More than 42 percent of U.S. adults smoked in years preceding the report; that rate has dropped to about 18 percent.

The researchers say their calculation – 8 million deaths – equals lives saved thanks to anti-smoking efforts.

Their report also says tobacco controls have contributed substantially to increases in U.S. life expectancy. For example, life expectancy for 40-year-olds has increased by more than five years since 1964; tobacco control accounts for about 30 percent of that gain, the report says.

The conclusions are just estimates, not hard evidence, but lead author Theodore Holford, a biostatistics professor at Yale University’s school of public health, said the numbers “are pretty striking.”

Yet smoking remains a stubborn problem and heart disease, cancer, lung ailments and stroke – all often linked with smoking – are the nation’s top four leading causes of death.

The U.S. Centers for Disease Control says about 443,000 Americans still die prematurely each year from smoking-related causes.

“Tobacco is, quite simply, in a league of its own in terms of the sheer numbers and varieties of ways it kills and maims people,” Dr. Thomas Frieden, the CDC’s director, wrote in a JAMA commentary.

Frieden said the United States lags behind many other countries in adopting measures proven to reduce tobacco use, including graphic health warning labels on cigarettes, high tobacco taxes and widespread bans on tobacco advertising.

“Images of smoking in movies, television and on the Internet remain common; and cigarettes continue to be far too affordable in nearly all parts of the country,” Frieden wrote.