A landmark 50-year medical study from Great Britain shows that at least one-half of those who begin smoking young are eventually killed by the habit. Many of those deaths occur between ages 35 and 59.
"British men born in the first few decades of the 20th century could be the first population in the world in which the full long-term hazards of cigarette smoking, and the corresponding benefits of stopping, can be assessed directly," writes lead researcher Richard Doll, MD, emeritus professor of medicine at the University of Oxford, who launched the study in the 1950s when he was in his 30s.
His first report in 1954 confirmed the link between smoking and lung cancer. Now in his 90s, Doll has published his full report in the latest British Medical Journal.
The report is based on the 34,439 doctors' annual questionnaires about their health habits, including smoking, from 1951 until 2001. Causes of death were noted for every doctor. Doctors were studied because the researchers felt doctors may be more accurate about their smoking.
Among the findings:
- About 42% of smokers who started young could expect to die early (before age 70) from smoking-related diseases -- 10 years earlier, on average. Some lost a few decades of life, Doll notes.
- The tobacco-related causes of death included lung cancer; heart disease; cancers of the mouth, pharynx, and esophagus; and respiratory disorders such as emphysema.
Daily cigarette smoking was highest during World War II, especially among men -- three times greater than the previous years, writes Doll. Their habit may have been even more intense at early ages, then continued for decades -- which caused the early deaths of more than half of those who continued smoking.
The earlier in life the participants stopped smoking, the more years they added to their lives.
- Stopping around age 60 added at least three extra years of life.
- Stopping around age 50 added six years of life.
- Stopping around age 40 added nine years.
Those who quit smoking before age 35 added 10 years of life -- and had a life expectancy similar to men who had never smoked. They "avoided almost all" of the risk, writes Doll.