'Cures' carry own risk for smokers

Smokers trying to wean themselves off cigarettes with the aid of skin patches or nicotine chewing gum could still be putting their health at risk, say scientists.

Laboratory tests have discovered that nicotine on its own can cause cancer. Previously, nicotine had been seen as the drug that kept smokers addicted to tobacco, but as relatively harmless in itself.

But scientists at Stanford University School of Medicine said that nicotine, at a concentration similar to that in the blood of smokers, promoted cancerous tumour growth and narrowed arteries in mice.

The researchers carried out laboratory tests with nicotine on human endothelial cells, which line the walls of blood vessels. The nicotine significantly increased the rate at which cells multiplied.

Nicotine "patches" were then placed under the skin of mice modelling different human diseases such as arterial disease, inflammation, blood starvation in the limbs and cancer.

The findings, reported in the journal Nature Medicine, showed that the drug accelerated growth of cancer tumours and fatty deposits on artery walls.

But anti-smoking pressure groups urged smokers trying to give up not to abandon nicotine patches and gums.

"It is important to keep a sense of proportion," said a spokesman for Action on Smoking and Health. "Taking off the nicotine patches is much more likely to kill you than keeping them on."

Each year, an estimated one in 10 of Britain's 13 million smokers tries to give up. Nicotine patches, chewing gum and inhalers have proved a popular means of kicking the habit.

The products provide a controlled "fix" of nicotine to satisfy the craving, without the harmful chemicals of cigarettes.