Pot, Crack May Hike Cancer Risk, Study Says

Long-term marijuana or cocaine smoking might increase the risk of lung cancer, suggests a small study that compared tissue samples from people who smoke tobacco and illegal drugs.

Scientists at UCLA found that smoking marijuana and crack can cause the same precancerous changes in bronchial cells that tobacco smoking causes. The changes occur well before a smoker gets cancer.

The study, reported in this week’s Journal of the National Cancer Institute, also found that smoking both tobacco and marijuana or cocaine increased the risk, because those smokers were more likely to sustain additional precancerous changes. Also, these combination smokers were more likely to have damage to their p53 gene, an important gene in fending off cancer.

The study compared respiratory tract tissue samples from 28 healthy volunteers and 76 smokers of tobacco, marijuana, cocaine or a combination of the drugs.

Epidemiological studies that have attempted to track cancer in marijuana users have had mixed results.