“In 2009 when the rules regarding the establishment of dispensaries changed, all of a sudden they showed up on my way to work and in my neighborhood. I wanted to know what it was all about,” says Daniel Bowles, MD. Here we talk with Dr. Bowles about his involvement with medical marijuana practice and policy, as well as the current knowledge of risks and benefits associated with the drug as they relate to cancer.
C3: You mentioned noticing a boom in medical marijuana dispensaries, but how did you move from seeing dispensaries to getting involved?

Bowles: A few years ago, the Colorado General Assembly passed laws that changed and clarified medical marijuana rules and regulations, and part of this reorganization was the establishment of a marijuana task force to advise policy makers. I heard about it on public radio and thought it sounded interesting. It turned out the advisory committee was looking specifically for an expert in cancer. I applied for the position and was selected as the oncology representative.

C3: I think most people are fairly comfortable with the idea of medical marijuana used to alleviate symptoms in cancer patients. Do you see other potential uses of the drug?

Bowles: First, I think it’s important to make the distinction between the plant and “drugs” that may be contained in the plant. There’s cannabis, the plant, and then there are cannabinoids, which are the 60-something active chemicals that happen to be derived from the plant.

C3: Are the potential benefits different? Wouldn’t the plant itself have similar implications for cancer as the drugs the plant contains?

Bowles: When we give patients paclitaxel chemo¬therapy, we don’t give them the whole yew tree. Paclitaxel was originally derived from natural sources, but its clinical use required being able to properly dose it and control its effects. Similarly, smoking or ingesting cannabis is far too uncontrolled, too variable, for use in a clinical setting, but studying and then administering drugs based on cannabinoids is a real possibility.

C3: And do you see promise in this possibility?

Bowles: Well, it’s been a bit difficult to study. Cannabis is a Schedule 1 drug by federal law, and much of funding we receive in a university research setting comes from the federal government through agencies like the National Institutes of Health and National Cancer Institute. There have been a decent number of preclinical studies of cannabinoids and their role in cancer suppression or growth inhibition, particularly with prostate, breast and brain cancers. This work is still in its very early stages, but in my opinion it’s a line of research worth following.

C3: Are there also cancer risks associated with cannabis or cannabinoids?

Bowles: The big worry is whether there’s an increase in smoking-related cancers in chronic marijuana smokers. Studies thus far have been mixed. For example, a lung cancer study in Sweden followed people for 40 years and found a small increased risk of lung cancer in heavy marijuana smokers even when adjusted for cigarette use. But then a study of head and neck cancer found slightly decreased rates of oral cavity cancers but increased risks of oropharynx cancer in heavy marijuana users. While we know about the developmental and mental health issues associated with marijuana use, the science in terms of cancer is just now starting to catch up.

C3: Do you find it’s difficult or stigmatizing to be a researcher in this field?

Bowles: The field in general is a giant morass right now. It’s something many people feel strongly about, one way or the other. So in addition to science, you have belief and policy. We’re learning new things about cannabis and cancer every day, but what we know is only one piece of the puzzle, alongside very strong opinions. I try to focus on the science and not necessarily get embroiled in the emotion of the larger, societal debate.