Cutting down isn't enough, smokers told

Smokers were warned yesterday that cutting down on cigarettes is not enough to protect them against cancer.

Those who smoke more than a pack a day then reduce their consumption by around 90 per cent experience a fall of only half that much in the level of cancer- causing chemicals in their body, according to a study.

Researchers believe that when smokers try to cut back they experience withdrawal symptoms and so inhale longer and deeper on the few cigarettes they do smoke.

The findings will come as a shock to thousands of Britons who make New Year resolutions to give up smoking but may eventually settle for cutting down instead.

Lung cancer is the biggest cancer killer in the UK, causing more than 33,000 deaths every year - more than twice as many as bowel cancer, the next most deadly form of the disease.

Around 38,000 cases of lung cancer are diagnosed annually - 90 per cent of them caused by cigarettes - and only five per cent of victims live for more than five years.

In the latest study, scientists at the University of Minnesota studied a group of 153 heavy smokers, 102 of whom were asked to gradually cut down on cigarettes over several weeks.

Dr Stephen Hecht and colleagues measured the levels of NNK - a cancer-causing chemical unique to tobacco - in urine samples before the study began and then on a weekly basis.

Smokers who had reduced

their cigarette consumption by nearly two-thirds (63 per cent) by week 12 experienced a drop of only 28 per cent in NNK levels in their system.

Those who had managed to cut down by 74 per cent fared

little better, with a reduction of just 29 per cent.

The story was little better for the smokers who had cut down the most - from an average of 25 cigarettes a day before the study began to just 2.6 per day on average by week 12. This 90 per cent reduction in cigarettes smoked produced only a 46 per cent decrease in traces of cancer- causing substances recorded.

Such smokers were therefore gaining 4.3 times more NNK per cigarette than before the study, the Journal of the National Cancer Institute reports today.

Dr Hecht said that the most likely explanation is that smokers took larger puffs and shorter intervals between puffs to 'compensate' for the cutback in cigarettes.

'The results indicate that some smokers may benefit from reduced smoking, but for most the effects are modest,' he said.

Scott Leischow, of the U.S. National Cancer Institute, said: 'Given the dearth of evidence supporting the benefits of reduced smoking, and given the strong evidence that smoking cessation can have a dramatic impact on future tobacco-related mortality, the most dramatic health benefits will occur if we can significantly increase the number of smokers who quit.'

Dr Marcus Munafo, a tobacco research scientist with Cancer Research UK, said smokers were wrong to think that either cutting down on cigarettes or smoking low-tar brands would have much effect on their risk of cancer.

He said: 'People are addicted to nicotine and if they cut down on cigarettes, they just seem to suck harder and make more of each one. The basic message must be that there is no substitute for stopping all together.

'The sooner people stop the better because it takes ten years after quitting for the risk of heart disease to return to that of a non-smoker and 15-20 years for the risk of lung cancer.'