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By Shamard Charles, M.D. and Linda Carroll
Early in his career, Dr. Raja Flores knew that most of them were cigarette smokers. But over the years, Flores, a thoracic surgeon at Mount Sinai Medical Center in New York, noticed a surprising trend: some of his patients had never smoked a tobacco cigarette. They smoked a different drug: marijuana. And they had developed a much more aggressive form of lung cancer.
Initially, Flores did not think there could be a connection between marijuana and lung cancer. Research associating smoking with cancer was rare and inconclusive. But as the numbers grew, Flores wondered if he saw a new ominous trend.
"I thought," wait a minute, here's another person in their forties who has never touched a cigarette and cancer is everywhere, "Flores told NBC News." It's so bad that I can not even work. "
Flores recognizes that there is no scientific evidence that smoking cannabis causes lung cancer. But he fears that the combination of widespread legalization and commercialization of the potential health benefits of marijuana can lead to the belief that cannabis is a completely harmless drug. In fact, a nationally representative survey of American adults last summer found that almost one-third of those polled believed that smoking or spraying grass could protect a person's health. And this misperception could lead to the development of cancers due to marijuana use, but drug promoters do not detect it, says Flores.
According to Dr. Panagis Galiatsatos, a pulmonologist, an intensive care instructor at the Johns Hopkins School of Medicine, and director of the Johns Hopkins Medicine Tobacco Treatment Clinic, many Americans shared the same view of tobacco before collected evidence showing that smoking could cause lung cancer.
Until the number of cigarette-related lung cancer cases accumulates to a level that no-one can ignore, respected scientists have even dismissed warnings about the potential dangers of smoking, said Galiatsatos.
Does Marijuana Use Cause Lung Cancer?
Most research says no, but that does not mean that smoking joints in the long run is without consequences.
A 2016 study of health problems related to marijuana use found strong links between daily or near-daily marijuana use and chronic bronchitis, an inflammation of the lungs that causes coughing, wheezing and breathlessness.
"Smoked marijuana has effects on the airways for long periods of time," said Dr. Russell Bowler, director of the COPD Treatment Clinic at National Jewish Health in Denver. He is a member of the Public Health Advisory Committee of Marijuana in Retail for the Department of Public Health and the Environment of Colorado, which commissioned the study.
Bowler's research reveals that the daily or near-daily use of marijuana may be associated with bullous lung disease, air pockets forming in the lung disrupting its function, and pneumothorax, usually leading to a collapse of the lungs. lungs in young people.
Bowler said that more research was needed on smoking and developing lung cancer.
"There are very few publications [data] on secondary exposure and the lack of data to draw conclusions about its health effects, "Bowler told NBC News.
One of the reasons for the lack of data: Marijuana studies can not be done in the United States because, at the federal level, drugs remain in the same class as heroin and LSD, a Schedule I drug This means that marijuana is designated as having "high potential for abuse" and "no currently accepted medical use".
However, public health advocates of cannabis research in the United States believe that marijuana laws should not affect a scientist's ability to study the impact of the drug on a population.
Do not smoke anything
Researchers comparing cannabis and tobacco smoke say they could damage the lungs in the same way.
"Marijuana smoke contains many of the volatile chemicals found in tobacco smoke that are harmful to lung tissue," said Dr. Donald Tashkin, a pulmonologist and professor emeritus of medicine at UCLA's David Geffen School of Medicine.
"As a respirologist, I advise all my patients not to smoke anything," said Tashkin.
On the surface, marijuana smokers appear to be at a lower risk than cigarette smokers because they light fewer times a day. But researchers have discovered that many more carcinogens, such as tar, end up in the lungs when a joint is smoked, rather than in a cigarette.
This happens because marijuana is smoked differently than a normal cigarette. Traditional vaping or smoking of the joints usually involves inhaling the marijuana smoke deep into the lungs and holding it, giving the toxins more contact with the lungs. In addition, many marijuana users smoke a joint until the end.
Tar, a sticky substance left after burning, is concentrated at the end of a joint and contains a large amount of harmful substances that can damage lung cells.
Some research has shown that smoking a joint is comparable to smoking from 4 to 20 cigarettes.
These findings are one of the reasons why Tashkin expected to find a connection between smoking cannabis and developing lung cancer.
"Regularly smoking marijuana itself causes visible and microscopic lesions of the major airways, consistently associated with an increased likelihood of chronic bronchitis symptoms that disappear after cessation of consumption," said Tashkin.
He also found that pre-cancerous alterations developed in the lungs, but this often did not lead to cancer.
"In human studies on long-term marijuana users, we have found many pre-cancerous changes to the lungs," said Tashkin. "It does not mean that if you have these changes, you will develop lung cancer. But if this happens, you run an increased risk of doing so. "
Tashkin, who has co-authored numerous studies on the impact of marijuana on the lungs over the past 30 years, has even reanalyzed his own data. He only found an increased risk of lung cancer among heavy smokers in a small number of patients. The number was so small that Tashkin did not think it could be used as irrefutable evidence to support the conclusion that the pot could cause cancer.
Marijuana more powerful than ever
In the United States, marijuana is legal on medical prescription in 33 states and recreational in 11 states plus the District of Columbia.
Marijuana, unlike tobacco, has no control over its strength or quality, so people do not use the same amount in a single dose. In addition, people who use marijuana for medical purposes for nonspecific conditions such as pain treatment can change the amount of drugs they need to relieve themselves. Because of these factors, it is difficult for researchers to establish standards to measure the effects of the drug.
More potent forms of marijuana, sometimes called Skunk marijuana, may be one of the reasons people avoid lung cancer, despite ingesting the same carcinogens as combustible cigarettes, says Browler.
"Now, in Colorado, people are getting a product that consistently contains 30% THC. This means that people smoke a more powerful product and can smoke fewer times a day to achieve the same effect, "said Browler. "Some smokers smoke 1 to 3 packs a day, up to 60 cigarettes. You would not be alive if you smoked 60 joints a day at 30 times the amount of THC. "
Smoking is perhaps the most popular form of marijuana use, but the use of edible products has become increasingly popular and it does not affect the lungs, he added.
Experts agree that additional research is needed.
"In the early 1950s, leading scientists questioned the fact that smoking could cause lung cancer, but it's only after having counted more than 30 million cigarette smokers in the United States that the danger to the lungs began to appear, "Flores said.
"If we turn our backs on this now, we could have a big disaster later."