Dr. Donald Abrams Answers Questions about Medicinal Marijuana

By UCSF Today | October 18, 2006

As part of UCSF Today's new On the Spot web feature, Dr. Donald Abrams, the new director of clinical programs at the Osher Center for Integrative Medicine and an expert in complementary therapies, agreed to answer your questions.

Below we've published some of the questions you've asked of Dr. Abrams, along with his responses. As questions and comments continue to come in, this story will be updated with Dr. Abrams's additional responses.

Please remember that we may not be able to answer all questions or address all comments. Nor can we or the participating faculty member offer specific medical advice. For medical advice, you should always contact your personal physician.

Medicinal Marijuana
Q. In regard to medicinal marijuana, does marijuana smoke or secondhand exposure affect the lungs or throat like cigarette smoke or secondhand exposure?

A. With regards to secondhand marijuana smoke, I do not believe that such studies have been done. In general, inhalation of products of combustion is not the ideal way to deliver a medicine.

Donald Tashkin at UCLA has spent nearly 40 years investigating the harmful effects of inhaled marijuana on the lungs--from the electron microscopy level to airway responsiveness to the development of cancer. He has made some interesting observations. Chronic marijuana use seems to be associated with an increased risk of chronic bronchitis. Tobacco smokers who also smoke marijuana, however, seem to have less of a risk to develop emphysema. Most recently he has done a case control study of over 1,300 lung cancer patients in Los Angeles and has found that regular marijuana smoking does not lead to an increase in lung cancer, and may actually be associated with a decreased risk of lung cancer.

How is that possible, you may ask? Well, actually this seems to support an animal study and a previous epidemiologic cohort study which suggests the same. It may be that the anti-inflammatory and anti-oxidant effects of some of the components of marijuana are coming into play to explain this finding. There was one study that suggested that chronic marijuana smoking could be associated with an increased risk of head and neck cancers; however, that study was flawed by not controlling for the impact of tobacco smoking, which is a known risk.

More and more basic science studies are demonstrating that cannabinoids-the active ingredients in marijuana--may actually be worth investigating as anti-cancer agents! So that is a whole new line of interesting research that may be bearing fruit in years to come!

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