What to Know About Medical Marijuana

When used in medicine, marijuana is a highly regulated botanical that can often help manage cancer symptoms, from nausea and lack of appetite to chronic pain and more. Medical marijuana is one part of a larger movement of using integrative medicine to help cancer patients and survivors enjoy greater comfort, health and well-being.   

Michelle Loy, M.D., an Integrative Medicine Physician at Weill Cornell Medicine, recently shared her expert knowledge of integrative medicine and medical marijuana on an episode of the Weill Cornell Medicine CancerCast podcast.  

Integrative medicine 

Integrative medicine is an evidence-based approach to medicine that focuses on healing and well-being of the entire person. 

“I always say the seeds for integrative medicine were sown from my birth,” effused Dr. Loy. “While I was born in the US, my paternal grandfather was born in a small village in Taishan Guangdong province in China … he immigrated to the US and then obtained his medical degree ... My maternal grandmother regularly did T'ai chi ch'üan. And when visiting my grandparents in Asia as a child, I would remember being given these traditional Chinese medicine soups for various conditions and even in the US, I grew up on a mostly traditional Chinese diet.” 

She was also exposed to science and evidence-based medicine from her research scientist father and registered dietician mother. When Dr. Loy chose to pursue a career in medicine, she sought additional training and certification in nutrition, acupuncture and medical yoga.  

Today, she offers integrative medicine consultations and grows an integrative oncology group series. “During this series,” she explained, “we discuss topics of interest to patients, including food as medicine, botanicals, vitamin supplements, culinary herbs, traditional Chinese medicine herbs, medicinal mushrooms, acupuncture, movement, mindfulness, yoga, narrative medicine and, of course, medical cannabis.” 

What is medical marijuana?  

Medical marijuana (cannabis) is used for medicine and regulated by the state. Cannabis is a genus of a flowering plant. The term “medical marijuana” can refer to many different cannabis products. Each state has its own laws as to which conditions and symptoms are eligible for medical marijuana use.  

“Recently, actually in January of 2022, the qualifying conditions were actually expanded by the New York State Office of Cannabis Management, so that patients are no longer limited by a list of qualifying conditions to be eligible for the use of medical cannabis,” she explained, “and so the patient's certifying practitioner can use his or her clinical discretion to issue a certification for the medicinal use of cannabis.” 

Currently, physicians and scientists are researching the therapeutic properties of tetrahydrocannabinol (THC) and cannabidiol (CBD), as well as other minor cannabinoids. The cannabinoid is any substance that can join with the cannabinoid receptors in the body (CB1 and CB2). CB1 receptors regulate sleep, pain, appetite, metabolism, cognition, reward, the immune system, muscular pain and ocular pressure. CB2 receptors regulate inflammation, cell proliferation, pain and gastrointestinal motility.  

“THC and CBD, as well as the other more minor cannabinoids, bind to the CB1 and CB2 receptors in our body with different affinities,” detailed Dr. Loy. “And when the receptors are activated, the effects may include changes in the neurotransmitter levels, reduction in inflammation and changes in metabolism.”  

Scientists and physicians are also very interested in learning more about another biological compound in cannabis: terpenes. “Many of the terpenes found in cannabis are also found in other botanicals and food, including pine needles, lavender, black pepper, hops, citrus, carrots and chocolate,” she explained. These contribute to sedative, anti-anxiety, anti-depressant and anti-inflammatory effects, as well support for the digestive system.  

Who should not consider medical marijuana? Are there any negative effects?  

Dr. Loy cautioned that some should not consider medical marijuana, including those with active psychosis or active substance use conditions. It is also not recommended for those who are pregnant or breast/chestfeeding.   

Medical marijuana is not recommended for those under 25. “There are legitimate concerns about the potential negative effects on the developing brain, including short-term memory loss, decreased concentration, a decline in school performance and possible increased risk for future problematic cannabis use conditions and psychosis,” Dr. Loy explained.  

Medical marijuana may have negative or unwanted symptoms when taken with other medications. That is why it is important to seek care from a highly knowledgeable physician who understands medical marijuana and integrative medicine.  

What are the benefits of medical marijuana for cancer patients?  

Medical marijuana has been shown to effectively help patients with chemotherapy-related symptoms, including nausea, vomiting and chronic pain. “In fact, for chemotherapy-induced nausea and vomiting, the oral cannabinoids have been shown to be as effective as anti-emetics and in adults with chronic pain,” confirmed Dr. Loy. “Patients who are treated with cannabis or cannabinoids are more likely to experience a clinically significant reduction in pain symptoms.”  

“A prospective study of more than 2,700 Israeli elderly patients using cannabis,” she continued, “and their mean age was about 74 and their most common indications were pain, 66 percent of them and cancer, which was 60 percent of them. And 93 percent of the respondents reported improvement in their condition … but what was most interesting to me was that after six months, 18 percent of them were able to stop using opioid analgesics or reduce their dose.” 

The most common side effects of medical marijuana are a little bit of nausea and dry mouth, although some experience cardiovascular or neurological side effects. Dr. Loy asserted that these side effects can be minimized by talking to your doctor and trying a different dose or form of administration.  

Advice to those considering medical cannabis  

“The best way is to think of it as one of the many tools in the toolbox,” advised Dr. Loy. She shared that her cancer patients often want to minimize many different symptoms: anxiety, insomnia, pain, neuropathy or poor appetite. An integrative approach, which may include medical cannabis, can help address all symptoms to promote greater comfort. 

“Medical cannabis is one way,” she said, “with one botanical, of being able to address multiple symptoms. Patients may have preconceived notions about it. But once we explain that it is a botanical, just like any herb or plant, used in a proper setting under the proper guidance, it can be very helpful from a quality of life perspective. And even more importantly, can help the patients with various symptoms adhere to the regimen that the oncologist is recommending to be the very best for the patient.”  

Be sure to listen to the full podcast episode featuring Dr. Loy and learn more about the expert care from the Weill Cornell Medicine Integrative Health and Wellbeing Program.