The risk of lung cancer in smokers is the same no matter how low the tar rating of the cigarette brand, according to major research published today.
The study of over 900,000 men and women in the United States found that all current smokers have a far greater risk of lung cancer than people who had never smoked or had quit.
Initiated by the American Cancer Society, the Cancer Prevention Study II represents long-term prospective research, which makes the results especially relevant.
They show that irrespective of the tar level of their brand, all current smokers had a much increased risk of lung cancer than people who had stopped smoking or never smoked. Compared with smokers of medium-tar (15-21 milligrams) filter cigarettes, the risk of cancer was higher for those who smoked high-tar (more than 22mg) non-filter brands.
Nor was there any difference in risk among men and women who smoked brands rated as very-low-tar (less than 7mg) or low-tar (8-14mg) compared with those who smoked medium-tar brands.
Dr Jeffrey E. Harris and his colleagues began the research in 1982. The study made allowances for the participants' diet and occupation. People who had smoked pipes or cigars or who had chewed tobacco in the past were excluded from the study.
Mortality from lung cancer among the different groups of smokers, all of whom were over 30, was measured six years later.
Prior to today's results, published in the British Medical Journal, no large, long-term study has specifically compared the risk of lung cancer in smokers of medium-tar, low-tar and very-low-tar cigarette brands.
Noting that their results are consistent with evidence that people smoke low-tar cigarettes more intensively, the authors point to the phenomenon of "compensatory smoking". "Addicted smokers who switch from a higher to a lower tar cigarette maintain their nicotine intake by increasing the time during which smoke is retained in the lungs and by smoking more cigarettes."
Reuters adds: Anti-smoking groups in Britain yesterday expressed concern at how low-tar cigarettes are marketed, despite reassurances from the tobacco industry.
Mr Tim Lord, chief executive of the Tobacco Manufacturers Association in London, said low-tar cigarettes were never advertised or promoted as healthier. "At the end of the day, the only safe cigarette is no cigarette," he said.
Ms Amanda Sandford of the anti-smoking group ASH (Action on Smoking and Health) said the promotion of low-tar cigarettes, particularly to women, had health implications even if it was not overtly saying they were safer.
"The level of tar in a cigarette doesn't matter. It is still going to cause cancer if you continue to smoke for many years."