By Melissa Weber

The Supreme Court’s recent decision to impose a federal ban on the use of medical marijuana won’t make much difference for cancer patients, says oncologist James Vredenburgh, MD, from Duke University Medical Center. “I don’t think it will be an issue because marijuana is so readily available in our society.”

Dr. Vredenburgh says that although North Carolina state law doesn’t allow him to prescribe marijuana, “a number of my patients have tried it with my encouragement, and it’s made a huge difference for chemotherapy side effects.” Side effects sometimes treated with marijuana (Cannabis sativa) include nausea and vomiting, cachexia (weight loss), mood and pain.

But a survey of about 1,100 clinical oncologists puts Dr. Vredenburgh in the minority. Because effective palliative care drugs are available, only 1 percent of oncologists said they recommended or prescribed marijuana over a two-year period, and only 30 percent of responders supported legalizing marijuana for medical use in the United States. Medicinal marijuana is currently legal in Canada and the Netherlands.

Six percent of surveyed oncologists, though, had prescribed an oral drug called Marinol® (dronabinol), which contains the cannabinoid THC (tetrahydrocannabinol), an active ingredient in marijuana. The Food and Drug Administration approved Marinol in 1985 to treat nausea and vomiting in chemotherapy patients. Studies show that the drug, which is typically covered by insurance, also improves appetite in cancer patients. However, some patients report dissatisfaction with the oral drug because it takes one to three hours to enter the bloodstream, whereas by smoking marijuana, THC is absorbed into the bloodstream within minutes.

“It’s hard to titrate the dose of THC in a pill form, so in a lot of ways smoking is better because it delivers the drug more quickly and patients can titrate themselves better,” says Billy R. Martin, PhD, director of the Center on Drug Abuse Research at Virginia Commonwealth University.

Dr. Martin says political and social baggage complicate the fact that patients report relief from smoking marijuana, but the reasons behind the effects are becoming clearer. Scientists now know that THC binds to and activates specific cannabinoid receptors in the brain. Since these receptors were found, scientists have discovered a handful of endogenous cannabinoids that naturally occur in the body.

“In the past 15 years, we’ve unraveled the greatest mysteries in this field and now know that there’s this biological system—the endocannabinoid system,” says Dr. Martin. “We’re looking at how this biological system regulates appetite and what role it plays in pain, normal brain function and the nervous system. We know that THC works on the endocannabinoid system.”

Though doctors typically reserve cannabinoids for patients who do not respond to standard palliative care drugs, Dr. Vredenburgh says he tries the alternative early on if he thinks the patient will derive benefit. “I usually prescribe Marinol first because as a physician that’s what I’m allowed to do. But if for financial reasons or other reasons the patient prefers to smoke marijuana, that’s what they do.”

Dr. Vredenburgh says a patient should first discuss marijuana use with a doctor because the central nervous system can be adversely impacted, causing depression, hallucinations and paranoia. “Like with any drug, patients have to start out slow. See how you do and see how you feel.”

Solvay Pharmaceuticals, maker of Marinol, is currently testing a spray version of the drug. Though it will likely be years before the FDA considers the Marinol spray for approval, an under-the-tongue spray called Sativex® was approved in Canada in April. Indicated for chronic nerve pain in multiple sclerosis patients, Sativex contains THC and CBD (cannabidiol).

Dr. Martin says that by understanding the endocannabinoid system, scientists will better understand how marijuana works. “The future is in the science. You can say what marijuana does and doesn’t do, and you can do it with precision. There aren’t much politics involved with a receptor.”