Marijuana and Lung Cancer: Another Marijuana Myth Goes Up in Smokeby Paul Armentano

2 min read

Epidemiological data presented last May at the International Conference of the American Thoracic Society (ATS) concluding that smoking marijuana, even long-term, is not positively associated with increased incidence of lung-cancer, is just the latest in a long line of government claims regarding the alleged dangers of pot to go – pardon the pun – up in smoke.

Investigators from the David Geffen School of Medicine at the University of California assessed the possible association between cannabis use and the risk of lung cancer in middle-aged adults (ages 18–59) living in Los Angeles. Researchers conducted interviews with 611 subjects with lung cancer and 1,040 controls matched for age, gender, and neighborhood. Data was collected on lifetime marijuana use, as well as subjects’ use of alcohol, tobacco and other drugs, diet, occupation, and family history of cancer. Investigators used a logistical regression model to estimate the effect of cannabis smoking on lung cancer risk, adjusting for age, gender, ethnicity, education, cumulative tobacco smoking, and alcohol use.

“We did not observe a positive association of marijuana use – even heavy long-term use – with lung cancer, controlling for tobacco smoking and other potential cofounders,” investigators concluded. Moreover, their data further revealed that one subset of moderate lifetime users actually had an inverse association between cannabis use and lung cancer. Much less surprising, the NIH-funded study – the largest of its type ever conducted – did find a 20-fold increased risk in heavy tobacco smokers.

Officials from the White House’s Drug Czar’s office had “no comment” on the UCLA findings.

While the investigators’ failure to demonstrate a positive association between cannabis use and cancer may seem surprising to some, the bottom line is that scientists overseas have been studying pot’s potential anti-cancer properties for nearly a decade. Most recently, investigators at Italy’s Instuto di Chemica Biomolecolare reported in the May issue of the Journal of Pharmacology and Experimental Therapeutics that compounds in marijuana inhibit cancer cell growth in animals and in culture on a wide range of tumor cell lines, including human breast carcinoma cells, human prostate carcinoma cells, and human colectoral carcinoma cells.

Previous studies by European researchers have shown that cannabis’ constituents can reduce the size and halt the spread of glioma (brain tumor) cells in animals and humans in a dose dependent manner. Separate preclinical studies have also shown marijuana to inhibit cancer cell growth and selectively trigger malignant cell death in skin cancer cells, leukemic cells, and lung cancer cells, among other cancerous cell lines.

But none of these findings should come as a surprise to the US government, which ironically, sponsored the first experiment ever documenting pot’s anti-cancer effects in 1974 at the Medical College of Virginia. The results of that study, reported in an August 18, 1974, Washington Post newspaper feature, were that marijuana’s primary psychoactive component “THC slowed the growth of lung cancers, breast cancers and a virus-induced leukemia in laboratory mice, and prolonged their lives by as much as 36 percent.”

Shockingly, federal officials have steadfastly refused to fund any follow up research on the subject in the following decades, and today continue to oppose any use of cannabis – even for medical purposes in states that have authorized its use. What’s the Fed’s rational for maintaining such a foolish and misguided policy? Most likely, they have “no comment.”

About the Author:
Paul Armentano is the senior policy analyst for The NORML Foundation in Washington, DC. Additional articles by Paul Armentano are available at, where this article was originally posted.