Anti-smoking measures have saved roughly 8 million US 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 on Tuesday in the Journal of the American Medical Association (JAMA). This week’s issue commemorates the 50th anniversary of the US 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 US 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 US 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 top four leading causes of death in the US.

The US Centers for Disease Control (CDC) says about 443,000 Americans still die prematurely each year from smoking-related causes. CDC director Thomas Frieden said in a JAMA commentary that the US 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.

He cited data showing 32 countries have done better at raising tobacco taxes, and at least 30 have adopted stronger cigarette warning labels.