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Does Smoking Marijuana Cause Lung Cancer?

Dr. Raja Flores Mount Sinai Health System

“As someone on the front lines, who sees this every day, I’ve seen lung cancer caused by marijuana that is incredibly aggressive,” says Dr. Raja Flores, Chairman of the Department of Thoracic Surgery for the Mount Sinai Health System.

While half the country is trying to legalize marijuana and touting its benefits in the medical world, no one seems to be asking the logical question … does smoking pot cause lung cancer?


We all know we’re not supposed to smoke cigarettes – the correlation between smoking and lung cancer is clear. But we live in a society that perpetuates the idea that smoking weed is not as harmful, or not harmful at all. Dr. Flores has a drastically different view on the subject but the lack of good data means that, for the moment, it’s just his informed opinion and can’t be applied across a whole population of pot-smokers.

Because marijuana use was illegal throughout the United States until a few years ago, and is now legal in only a few states, researchers attempting to study a link between smoking pot and lung cancer have had to work with very limited data. They’ve had to assume that people were underreporting how often they smoked or simply lying about use to avoid any legal issues. Studies attempting to examine the risk do suggest that smoking weed increases the risk of lung cancer, but that suggestion is not conclusive.

“There is no real good population-based study that looks at marijuana smoking and that has had enough time elapsed to show it’s associated with lung cancer, [but] I’ve seen it. I’ve seen multiple, multiple cases of it. I see it every day,” Dr. Flores says.

Another issue doctors see when trying to measure lung damage from marijuana use is how often people smoke it. It could be possible that smoking pot is just as harmful as smoking cigarettes, but pot smokers tend to experience fewer symptoms because they usually smoke less often.

“Marijuana smoke contains many of the same carcinogens as cigarette smoke, but not all of them,” Dr. Peter Shields of Ohio State University’s Wexner Medical Center says. “Conceptually there would be an increased risk, but this is not clearly established from the available scientific studies, and as important, the dose needed to measurably increase risk is not known.”

So what will it take for researchers to actually be able to conclude without a doubt that smoking marijuana causes lung cancer? Probably Federal legalization, which would legalize use in all 50 states. Such widespread legalization might facilitate the accumulation of data regarding marijuana usage because of the absence of legal consequence for users.

Dr. Flores predicts that once marijuana becomes an accepted part of American culture, the risks associated with smoking will become clearer. “What you’re going to see going down the line is the reincarnation of the whole tobacco disaster,” he says. “I see it now already.”

In a study published in the Advances in Experimental Medicine and Biology book series, researchers concluded that “heavy use of cannabis on its own can cause airway obstruction. Based on immunohistopathological and epidemiological evidence, smoking cannabis poses a potential risk for developing lung cancer. At present, however, the association between smoking cannabis and the development of lung cancer is not decisive.”

Due to the excitement surrounding the legalization of both medical pot and recreational pot, the lack of studies on the issue makes sense. This is a multibillion dollar industry, and many people stand to make a lot of money from marketing marijuana. “Big business and the money influence is taking precedence over the health issues,” Dr. Flores warns.

Although many people suffering from chronic pain or nausea induced by chemotherapy say that medical marijuana has been a godsend for managing their symptoms, the health risks of heavy pot use could even be comparable to those associated with heavy drinking.

“There is a lobby out there that is trying to say that marijuana is better than drinking, that it’s safer, that it doesn’t cause cancer, and that you should do that,” Dr. Flores says. “They’re both bad.”

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Dr. Raja Flores is Chairman of the Department of Thoracic Surgery for the Mount Sinai Health System. Read More