When Can Cannabis-Based Medicines Negatively Affect Cancer Patients’ Health?
In recent years, it’s become increasingly common to hear about new uses for cannabis in cancer therapy. While scientists confirm that cannabinoids can be highly effective in palliative care for cancer patients and may even slow the growth of cancer cells, the internet and specialized media are overflowing with stories and testimonials attributing almost miraculous properties to the plant-such as claims that it can destroy inoperable tumors after a single use. (It’s worth noting that some studies do confirm such properties for CBD and THC molecules.) In other words, it’s hard to imagine a more sensational topic in the entire field of cannabis medicine.
Despite public enthusiasm-many people already see cannabinoids as a cancer cure-most doctors remain cautious, even with scientific data available. Their skepticism is based on the limited understanding of the molecular structure of cannabis and how it interacts with the human body, particularly the endocannabinoid system. Some experts are still not convinced by the evidence of cannabinoids’ therapeutic effectiveness, believing that these substances only temporarily slow the spread of harmful cells. Finally, a small but significant number of medical professionals believe that cannabinoids may actually have carcinogenic properties and could stimulate the progression of deadly diseases.
Supporting this last viewpoint is the unfortunate fact that, despite years of research, doctors have not yet established a clear link between cancer tumors, the immune system, and the modulation of the endocannabinoid system by plant-based or synthetic substances. More specifically, based on data showing that certain concentrations of cannabinoids can suppress the immune system, some doctors suggest that cannabis use could make the body more vulnerable to disease and its progression. In early 2019, a study analyzed a large group of patients who used cannabis as an adjunct to standard chemotherapy. The study found that, in many cases, when cannabis was used alongside other immunotherapy drugs, its active compounds could negatively affect patients’ health by slowing down the body’s excretory system, which in turn delayed the removal of toxins and pathogens.
The Impact of Cannabinoids on the Human Immune System
“The goal of cancer immunotherapy is to use various drugs, such as Nivolumab, to stimulate the patient’s immune response, allowing their own cells to attack diseased tissues,” explains Dr. Chanda Macias, director of the National Holistic Healing Center. “In other words, we use exogenous, synthetic drugs to compensate for deficiencies in the patient’s immune system, helping the body resist disease progression and contain the spread of affected cells.”
Dr. Macias, who holds a degree in molecular and cellular biology, has spent the last 15 years studying and applying cannabis in therapeutic settings. Throughout her career, she has seen many cases where different types and forms of cannabis-based medicines were used in cancer therapy, both as an adjunct and as a primary treatment. While she and many colleagues confirm the high effectiveness of cannabinoids in palliative care and in combination with chemotherapy, she also notes that improper use of cannabis extracts-which usually have healing and pain-relieving effects-can sometimes cause serious and even dangerous side effects for patients.
“Medicine has now confirmed that some cannabinoid compounds have immunomodulatory effects,” says Dr. Macias. “Mainly, this effect manifests as a weakening of the body’s immune-inflammatory response, particularly by raising the pain threshold, which temporarily delays the immune response to pathogens and irritants.”
This effect is what gives cannabis its noticeable therapeutic benefits in relieving pain, inflammation, and muscle numbness. However, what is beneficial in treating some conditions can be extremely harmful in cancer therapy, precisely because it further slows an already compromised immune system.
Of course, not all cannabinoids have the same effect. Research and clinical observations show that THC has an immunomodulatory effect-it can either strengthen or weaken the immune response depending on various factors, including the presence of irritants or pathogens, dosage, and method of consumption. CBD, on the other hand, is recognized as a therapeutic and sedative cannabinoid without significant psychoactive effects, but it has a purely immunosuppressive function, weakening the body’s defense system and reducing discomfort.
“Unfortunately, because CBD is widely known as a ‘therapeutic cannabinoid’ and most doctors lack proper knowledge about medical cannabis, people often use CBD extracts alongside chemotherapy, not helping themselves but actually worsening the results of the treatment by disrupting the immune response,” Dr. Macias explains.
The Need for Further Research on Cannabinoids in Cancer Therapy
Currently, most countries still block formal clinical trials on the use of cannabis or its active compounds in cancer therapy. As a result, the global scientific community relies on practical observations and small-scale experiments to study the effects of cannabinoids on cancer treatment. Even with limited data, doctors have already identified patterns suggesting that CBD may be more harmful than helpful in cancer therapy.
One U.S. report analyzed medical histories of cancer patients from several states where cannabis is legal. It found that people who did not use cannabis extracts during chemotherapy responded much better to treatment than those who used cannabis at the same time. The study included 140 people with various forms of cancer, from relatively mild cases to advanced, inoperable tumors. While the authors could not specify which types of cannabis products were used, it is known that Nivolumab-a widely used chemotherapy drug-was part of the immunotherapy protocol.
Specifically, 89 patients used only Nivolumab, while the remaining 51 used the drug along with various forms of cannabis oil extracts. At the end of treatment, about 37.5% of the first group reported overall improvement in their well-being. In the group that used cannabis with the immunosuppressive drug, only 15.9% reported improvement, likely because cannabinoids weakened the main therapy’s effect.
Significant differences in post-treatment well-being were observed among patients with certain types of cancer, especially those diagnosed with carcinoma and melanoma. About 40.7% of patients who used only Nivolumab reported improved health after chemotherapy, compared to just 10% of those who used cannabis with the drug. Although patients used various forms and concentrations of cannabis extracts, the chemical composition did not seem to significantly affect the negative, immunosuppressive effect observed.
Despite these findings about CBD’s properties in cancer therapy, the authors also note that aside from reducing chemotherapy effectiveness, cannabis did not negatively impact patients’ long-term survival chances. In fact, cannabinoids may help slow disease progression.
Overall, many doctors, including Dr. Macias, believe that the small sample size and lack of precise information about the cannabis extracts used may distort the real impact of therapeutic cannabis on cancer progression and its effects when combined with chemotherapy. “Interestingly, even though cannabis can slow the immune response and the removal of toxins used in therapy, this study also confirms other known effects of cannabis, such as its general tonic and pain-relieving properties, as shown by the lack of significant changes in patients’ survival rates,” Dr. Macias notes. “Clearly, we need more in-depth research in this area to fully understand all the nuances of how cannabinoids affect cancer treatment.”
Original author: Emma Stone