A new review of the available scientific evidence suggests that cannabinoids present in medical cannabis may both enhance the efficacy and minimize side effects associated with conventional cancer treatments.
The 23-page paper, published online this month in the journal Pharmacology & Therapeutics, assesses a range of clinical and preclinical findings that “mainly relate to combination treatments for glioblastoma, hematological malignancies and breast cancer, but also for other cancer types.”
The report concludes that “the available data raises the prospect of cannabinoids increasing the efficacy and reducing the side effects of chemotherapeutic drugs.”
There are only a few studies that have been done on cannabinoids’ anti-cancer effects. These are mainly focused on determining whether the compounds are harmful to cancerous cells. Other research, authors point out—including into the immune system and cannabinoids’ effects on angiogenesis (the formation of new blood vessels), invasion and cancer metastasis—”is still pending.”
In general, even though the interactions of cannabinoids to chemotherapy “represent a complex topic with many unknown variables,” according to the study, “there are two important therapeutic-relevant aspects” of this interaction. “First, systemic potentiation by cannabinoids of chemotherapeutics can lead to a longer life span by overcoming therapy resistance. Second, reduced side effects of chemotherapy.”
Researchers at Rostock Medical University Center in Germany’s Institute of Pharmacology and Toxicology authored the new paper.
The first portion of the review, focusing on efficacy of chemotherapeutics in combination with cannabinoids, looks in large part at a 2021 Phase 1b clinical study involving a combined THC–CBD oral spray, which showed that patients had a longer survival time when the spray was combined with the drug temozolomide.
This book discusses many other types of cancers such as leukemia, blood and bone-marrow cancers.
Second, cannabinoid treatment is examined as a way to treat chemotherapy-related side effects. This includes nausea.
The report states that “in addition to the well-known antiemetic effects of cannabinoids”, “an increasing amount of preclinical research discussed in this overview has shown in recent times that cannabinoids have a beneficial effect on chemotherapy side effects, such as chemotherapy induced peripheral neuropathy, nephrotoxicity and cardiotoxicity, or cystitis, mucositis, and cytotoxicity.”
It is noted that, while the report does not go into detail about cancer-related pains and symptoms, cannabinoids have been used to treat cancer-related chronic inflammation.
The report states that “Cannabinoids are used for a variety of reasons in cancer therapy.”
One matter that authors said needs further investigation is the potential for negative interactions between cannabinoids and chemotherapy drugs, noting that there are “several interactions…that are theoretically possible but have not yet been sufficiently investigated” as well as “further findings that give rise to speculation about possible interactions between cannabinoids and chemotherapeutic agents.”
However, they said that “it’s also possible” that cannabinoids cause yet-unknown interactions that are beneficial to the patient.
Question remain about the “amount to which route of administration affects the interaction with chemotherapy agents” – particularly when it comes to cannabinoids, where widespread smoking has a significant influence.
This report states that well-controlled trials for cancer are needed urgently to prove cannabinoids’ effectiveness as an addition medication in existing chemotherapies. The report concludes that “the extensive preclinical evidence on cannabinoids’ interaction with chemotherapeutics at the tumor cell death level should also be expanded to include the effects of this combination at levels of cancer progression such as invasion, angiogenesis and metastasis.”
This paper ends by reminding us that although humans have been using cannabis for thousands of centuries, it is only in the last few decades that we’ve had the ability to conduct scientific studies on its effects.
It says that “cannabinoids were used for many thousands of years in different forms,” but “it was only possible to study the pharmacological mechanism of action of cannabinoids since the discovery in early 1990s of the endocannabinoid systems.” They could therefore have therapeutic effects yet unknown on cancer development and progression.
Separately, U.S.-based researchers last month published what they described as the “largest meta-analysis ever conducted on medical cannabis and its effects on cancer-related symptoms,” finding “overwhelming scientific consensus” on marijuana’s therapeutic effects.
The study, published in the journal Frontiers in Oncology, analyzed data from 10,641 peer-reviewed studies—what authors say is more than ten times the number in the next-largest review on the topic. It says the findings “indicate that there is a growing consensus in the scientific community about the therapeutic effects of cannabis, especially when it comes to cancer.”
In light of the “scattered heterogeneous” research on the therapeutic benefits of marijuana that is described in the report, the authors sought to “systematically evaluate the literature on medical cannabis focusing on therapeutic potential, its safety profiles, as well as the role it plays in cancer treatments.”
“We expected controversy. In a press release, Ryan Castle, the lead author and head of research for Whole Health Oncology Institute said that they found a scientific consensus. This is the most convincing and dramatic proof of medical marijuana’s effectiveness in the treatment of cancer that has been seen by the scientific community.
In a press release, the Whole Health Oncology Institute stated that “the meta-analysis showed that for each study which showed that cannabis was not effective, there were at least three studies that proved it to be beneficial.” “That 3:1 ratio—especially in a field as rigorous as biomedical research—isn’t just unusual, it’s extraordinary.”
According to the institute, “the level of agreement found here is comparable or even exceeds many other institutions.” [Food and Drug Administration]-approved medications.”
Also last month, government and university researchers out of South Korea report that they have successfully identified a new cannabinoid—cannabielsoxa—produced by the cannabis plant as well as a number of other compounds “reported for the first time from the flowers of C. Sativa.” “The team tested 11 isolated cannabis compounds for their anti-tumor activity in neuroblastoma cancer cells and discovered that seven showed “strong inhibitory activity.”
A separate study of medical marijuana patients in Minnesota, published in February, found that people with cancer who used cannabis reported “significant improvements in cancer-related symptoms.” It also stated that high marijuana prices can burden less-financially stable patients, and “raise questions about the affordability and accessibility of this therapy.”
The National Cancer Institute (NCI) late last year estimated that between about 20 percent and 40 percent of people being treated for cancer are using cannabis products to manage side effects from the condition and associated treatment.
According to the agency, “the growing popularity of marijuana products among cancer patients has been correlated with the number of states who have legalized medical cannabis use.” But research is still lagging on which cannabis products will be effective in treating cancer-related symptoms, and side-effects of treatment.
In the NCI article, a set of scientific studies published in JNCI Monographs were cited. That package of 14 articles detailed the results of broad, federally funded cannabis surveys of cancer patients from a dozen agency-designated cancer centers across the country—including in areas where marijuana is legal, permitted only for medical purposes or still outlawed.
Just under one third (32,9 percent) of cancer patients have reported that they use cannabis. Respondents said marijuana was used primarily for treating symptoms related to treatment and cancer, such as sleep problems, pain, and mood swings. Report: The report states that the most popular perceived benefits are “pain, sleep, anxiety, and side effects of treatment.”
Separately, another recent study, in the journal Discover Oncology, concluded that a variety of cannabinoids—including delta-9 THC, CBD and cannabigerol (CBG)—”show promising potential as anticancer agents through various mechanisms,” for example by limiting the growth and spread of tumors. However, the authors acknowledge that obstacles remain to incorporate cannabis in cancer treatments, like regulatory barriers, and that optimal dosing is still needed.
Other recent research on the possible therapeutic value of lesser-known compounds in cannabis found that a number of minor cannabinoids may have anticancer effects on blood cancer that warrant further study.
While cannabis is widely used to treat certain symptoms of cancer and some side-effects of cancer treatment, there’s long been interest in the possible effects of cannabinoids on cancer itself.
A review of literature from 2019 found that the majority of studies were based on experiments in vitro, which means they didn’t involve humans but instead isolated cancer cells of human origin. Some of the research involved mice. Consistent with the latest findings, that study found cannabis showed potential in slowing the growth of cancer cells and even killing cancer cells in certain cases.
A separate study found that some cases, different types of cancer cells affecting the same part of the body appeared to respond differently to various cannabis extracts.
A scientific review of CBD last year also touched on “the diverse anticancer properties of cannabinoids” that the authors said present “promising opportunities for future therapeutic interventions in cancer treatment.”
Research from 2023 also found that marijuana use was associated with improved cognition and reduced pain among cancer patients and people receiving chemotherapy
Researchers at the University of Colorado discovered that, while the intoxicating effect of cannabis and its initial “high” may impair cognition temporarily, those who have used products of marijuana from dispensaries licensed by the state for more than two weeks report a clearer mind.
The National Institutes of Health in 2023 awarded researchers $3.2 million to study the effects of using cannabis while receiving immunotherapy for cancer treatment, as well as whether access to marijuana helps reduce health disparities.
On the political side, President Donald Trump’s recent choice to serve as the next White House drug czar has called medical marijuana a “fantastic” treatment option for seriously ill patients and said she doesn’t have a “problem” with legalization, even if she might not personally agree with the policy.
Under the Trump administration, “marijuana” is also now one of nearly two dozen “controversial or high-profile topics” that staff and researchers at the National Cancer Institute (NCI) are required to clear with higher-ups before writing about.
In a leaked memo, marijuana and opioids were listed along with COVID-19 vaccines, fluoride and measles as well as abortion, autism and diversity and gender ideologies. These are all believed to be the personal priorities of Health and Human Services Sec. Robert F. Kennedy Jr. and Trump.
NCI is a part of National Institutes of Health, which is itself a part of Health and Human Services.
Prior to publishing anything on the specified topics, NCI staff are required to send the materials to an agency clearance team, says the new memo, first reported by ProPublica.
Staff are advised that depending on the content of the material, it may require additional clearance and review by the NCI directors and deputy directors as well as the NIH or HHS. In some cases the materials will only need to be reviewed once, however the NCI Clearance Team may share them with NCI leadership and NIH or HHS.
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