Cutting down on cigarettes no cure for cancer

Smokers puff harder when smoking less, even when using the patch
21 January 2004

LAURA NELSON

The amount of carcinogens sucked up by smokers remains high even when they cut down on the numbers of cigarettes they smoke, a US study shows¹. Surprisingly, the same holds true even if they supplement their fix with nicotine patches.

The results indicate that nicotine patches aren't helping as much as they could, the researchers say. That's either because the patches don't deliver nicotine in the same way as cigarettes, or because there are other addictive substances in cigarettes that nicotine patches don't yet replace.

Either way, the study emphasizes that the best way to cut cancer risks is to quit completely, the researchers say. Half of long-term smokers will die prematurely as a result of their habit.

Breathe deep

Stephen Hecht of the University of Minnesota Cancer Center and his colleagues studied a group of 100 smokers, who reduced the number of cigarettes they smoked by up to 75% over six months. The team analysed the smokers' urine to measure a chemical marker for a particular cancer-causing agent found in cigarette smoke.

"We found that the decrease in the cancer compound was, on average, less than half of the drop in smoking," says Sharon Murphy, a biochemist in the research team. That's probably because the smokers are subconsciously feeding their addiction by inhaling more deeply on the few cigarettes they do smoke.

The results are consistent with previous studies which showed that smoking a large or small number of cigarettes exposes a smoker to similar amounts of thiocyanate - a chemical marker of cigarette smoke that is not a carcinogen. This was also thought to be because smokers inhale more deeply when smoking fewer cigarettes.

But the researchers were surprised that nicotine patches didn't make much difference to how long and hard the smokers puffed. Even when allowed to use as many patches as they wanted, the smokers still inhaled a disproportionate amount of carcinogens.

Patchy results

Murphy thinks this could be because the patches don't create the same 'high' as cigarettes. "There is not a big spike - or hit - of nicotine," she says.

Smokers may also be addicted to the physical act of smoking. "They like to have something to do with their hands," says Naj Dehlavi, a spokesperson for the charity Action on Smoking and Health (ASH) in London. "Smoking is a learned process, which might also be why nicotine patches don't always work."

A third possibility is that there are other addictive compounds in cigarette smoke that aren't in the patches. "This is highly likely," says Brett Paull, an analytical chemist at Dublin City University who worked on one of the thiocyanate studies.

The number of unknown substances in cigarette smoke is high, says Paull, and he thinks there are probably many more addictive compounds, at low levels, that have not yet been characterized.

"Nicotine patches are less than perfect," agrees Martin Jarvis, professor of health psychology at University College London. "But without replacements, uptake of carcinogens would be even higher."

 

References