Smokers who cut back the number of cigarettes they smoke may not be reducing the cancer-causing chemicals in their bodies as much as they had hoped, according to a report published on Tuesday.
The study, published in this week’s issue of the Journal of the National Cancer Institute, suggests that the benefits of cutting back are not nearly as significant as once thought, experts said.
When smokers smoke less, they probably drag longer and harder on every cigarette, the researchers said.
“The results indicate that some smokers may benefit from reduced smoking, but for most the effects are modest, probably due to compensation,” they wrote.
The scientists, led by Stephen Hecht of the University of Minnesota Cancer Center, tested 92 smokers over six months.
They looked specifically for the remains of NNK, one of the best-known carcinogens in tobacco smoke.
The smokers, who had enjoyed an average 23.7 cigarettes a day, agreed to systematically cut back how much they smoked — 25 percent fewer in the first two weeks, 50 percent fewer in the next two weeks and then by 75 percent, or more, if they could.
Urine tests showed that smokers who cut back by 55 percent to 90 percent reduced NNK by only 27 percent to 51 percent. Even smokers who were able to cut back to just two cigarettes a day reduced their NNK indicator levels by only 46 percent.
Quitting completely is betterIn a commentary, Scott Leischow and Mirjana Djordjevic of the Tobacco Control Research Branch at the National Cancer Institute said the study showed that completely kicking the habit is the only way to escape the damage done by cigarettes.
Dr. Michael Thun of the American Cancer Society agreed.
“These results support other evidence that when smokers reduce the amount they smoke or switch to reduced tar cigarettes, they modify the way they smoke in order to extract more nicotine and tar from each cigarette,” Thun said in a statement.
“The study complements other lines of evidence that suggest that quitting smoking is far more beneficial than reducing the number of cigarettes smoked. At least for lung cancer, the number of years spent smoking is far more important than the number of cigarettes smoked per day,” he added.
“Furthermore, even very low amounts of smoking are associated with substantial increases in the risk of heart attacks.”
Smoking causes 90 percent of all lung cancer cases and is the leading cause of heart disease, the No. 1 killer in the developed world
The study also showed how hard it is to quit. Six months into the study, 56 percent of the smokers had relapsed and were back to a pack a day or more.