Marijuana and cancer

There is propaganda by people who use marijuana that smoking it does not cause cancer, unlike any other kind of smoke. There is scientific evidence is that it might cause lung cancer.

I remember when people were denying cigarette smoking causes cancer.

Regardless of what the ultimate findings turn out to be between smoking marijuana and lung cancer, negative effects on the brain, esp. when used by young people, have been shown.

I'm not saying there are no cases where marijuana could be helpful. And I know that people who like it will disregard any facts they don't want to believe.

http://www.ncbi.nlm.nih.gov/pubmed/23846283

Oct 2013
Marijuana use and risk of lung cancer: a 40-year cohort study.
Callaghan RC1, Allebeck P, Sidorchuk A.

RESULTS:

At the baseline conscription assessment, 10.5 % (n = 5,156) reported lifetime use of marijuana and 1.7 % (n = 831) indicated lifetime use of more than 50 times, designated as "heavy" use. Cox regression analyses (n = 44,284) found that such "heavy" cannabis smoking was significantly associated with more than a twofold risk (hazard ratio 2.12, 95 % CI 1.08-4.14) of developing lung cancer over the 40-year follow-up period, even after statistical adjustment for baseline tobacco use, alcohol use, respiratory conditions, and socioeconomic status.

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http://lungcancer.about.com/od/causesoflungcance1/f/marijuana.htm

By Lynne Eldridge MD
Updated May 16, 2014

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More recent studies, in contrast, do appear to link smoking marijuana with lung cancer.

One study demonstrated a doubling in lung cancer for male marijuana smokers who also used tobacco (i.e. for men who smoked the same amount, the risk of lung cancer was twice as high for men who also used marijuana.) Another study found that long-term use of marijuana increased the risk of lung cancer in young adults (55 and under), with the risk increasing in proportion to the amount of marijuana smoked.

Why the controversy?

Since marijuana is illegal, it is hard to do the controlled studies that have been done with tobacco. Because of this, it helps to look at what we do know about marijuana:

Many of the carcinogens and co-carcinogens present in tobacco smoke are also present in smoke from marijuana.

Marijuana smoking does cause inflammation and cell damage, and it has been associated with pre-cancerous changes in lung tissue.

Marijuana has been shown to cause immune system dysfunction, possibly predisposing individuals to cancer.

Bottom line: Though marijuana most likely pales in cancer risk when compared to cigarette smoking, it's better to play it safe. There are reasons in addition to lung cancer risk (and the fact that it is illegal in most states) to avoid marijuana. Marijuana likely increases the risk of testicular cancer, prostate cancer, cervical cancer, a type of brain tumor, and the risk of leukemia in the offspring of women who use it during pregnancy.