(INTERVIEW) Gil Bar Sela - Cannabis in Cancer Treatment
- Today we'll look at the opinion of prominent Israeli scientist Gil Bar Sela, who is currently at the forefront of research into the healing potential of cannabis in oncology
The body of science examining the therapeutic effects of cannabis in cancer treatment provides a fairly strong basis for the view that this plant indeed has something to offer in helping against cancer.
However, it is currently emerging that the effects of cannabis are closely related to changes in the functioning of the human body's immune system.
This phenomenon could be problematic for researchers, especially for patients currently undergoing cancer treatment and various types of immunotherapy.
This is where Gil Bar Sela, head of the Department of Supportive and Palliative Care at the Rambam Health Care Campus in the Israeli city of Haifa, enters the scene, along with a team of specialized colleagues.
Gil Bar Sela and his colleagues decided to thoroughly examine the potential interactions between immunotherapy (the drug nivolumab) and cannabis compounds.
Study on Medical Cannabis and Its Interactions with Cancer Drugs
The researchers ultimately conducted a thorough retrospective observational study, during which records of a total of 140 patients receiving nivolumab between 2015 and 2016 were analyzed.
89 of these patients reported taking only cancer medications. The rest of the patients admitted to taking cancer medications and simultaneously using cannabis.
Patients were using nivolumab specifically for treating lung cancer and kidney carcinoma.
The resulting analysis showed that cannabis use was the only significant factor that modified patients' final response to nivolumab:
- 37.5% of patients who did not use cannabis had a positive effect from nivolumab
- Only 15.9% of patients simultaneously using cannabis had a positive effect from nivolumab
Despite the cancer drugs being less effective on patients under the influence of cannabis, there was no radical difference in the final survival rate and treatment success between the two groups.
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Professor Gil Bar Sela responds to these results and explains that although they are not yet conclusive, they must be taken into account from both a scientific perspective and from the patients' perspective.
Now let's look at 3 questions and answers directly from Professor Bar Sela.
1. What results and findings do you consider key here? Were any of them truly surprising to you?
"The absolutely crucial finding here is the fact that in patients using cannabis along with immunotherapeutic drugs, we observed a deterioration in the effectiveness of this type of drug.
Cannabis was the only factor among all observed that influenced the resulting effect of immunotherapeutic drugs.
Other parameters such as smoking, hypertension, and others naturally negatively affected the overall survival rate of patients. This is simply understandable, and we took it into account when grouping the results.
During retrospective studies, we collect all available data about all participating patients and then evaluate them using a multivariate regression model.
Of course, it can be expected that not all results will be beneficial or even make sense.
For example, results for lung cancer patients compared to patients with 'lighter' types of cancer show a dramatically lower survival rate for lung cancer patients, and so on. These parameters are directly related to the specific type of disease and other general life factors of the patients.
However, the connection between the effectiveness of immunotherapeutic drugs and cannabis use is a topic we should start focusing on.
It hasn't been discussed since the nineties when similar factors were observed in patients suffering from AIDS.
The current results again confirm that the interaction between cannabis use and immunotherapeutic drugs is indeed real and true. Cannabis suppresses the immune system response, just as was observed in the past."
2. How convincing do these results seem to you? Furthermore, what are the implications for patients using other types of immunotherapeutic drugs besides nivolumab?
"First, it's important to remember that we are working only with retrospective data. We should always take these with a bit of reservation.
Currently, we are working on another study during which we are collecting patient blood samples. Again, these are patients using immunotherapeutic drugs either in isolation or simultaneously with cannabis.
The following data should again help us understand what interactions between immunotherapeutic drugs and cannabis truly exist and to what extent immune system influence occurs.
Again, this is only a prospective trial study where we are collecting data from all patients using immunotherapeutic drugs. The heterogeneous nature of the participating patients and unknown differences between individual participants' immune system functions add to the difficulty.
In the end, this is 'only' another step that will subsequently lead us to a proper and detailed laboratory study of interactions between cannabis use and immunotherapeutic drugs.
So far, we know that there is a possible interaction between cannabis and all immunotherapeutics. This is not exclusive to nivolumab.
3. What would you advise practicing oncologists and cancer patient caregivers? What should they know about current research and how cannabis can affect their treatment?
"According to most previous studies, it appears that cannabis does indeed act as an immunosuppressant. In our retrospective study, we found that cannabis use had a negative impact on the action and effectiveness of immunotherapeutic drugs.
Personally, I always share this information with my patients. I think it's a very important piece of information that patients should know. Then they can decide how they want to continue treatment based on their free will.
However, it is still obvious that many more studies and data are needed. In any case, I think patients should know about this interaction now, not perhaps in a year or two.
Source:
"3 Questions On...How Cannabis Affects Cancer Treatment:... : Oncology Times." LWW, journals.lww.com/oncology-times/Fulltext/2017/11100/3_Questions_on___How_Cannabis_Affects_Cancer.29.aspx.