A federal health agency is acknowledging that a sizable portion—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.
Such widespread uptake by patients raises concerns that use is outpacing scientific knowledge on efficacy and risks, the agency said in a blog post published on Wednesday, but added that rescheduling marijuana could help remove current barriers to research to address the “scientific evidence deficit.”
“According to findings from several of the studies, anywhere from about 20% to 40% of people being treated for cancer use cannabis or cannabinoids,” the National Cancer Institute (NCI) post says, “often broadly referred to as medical marijuana—to help manage side effects like nausea, pain, sleeplessness, anxiety, and stress.”
“The growing popularity of cannabis products among people with cancer has tracked with the increasing number of states that have legalized cannabis for medical use,” it continues. “But research has lagged on whether and which cannabis products are a safe or effective way to help with cancer-related symptoms and treatment-related side effects.”
Nearly 3 in 4 Americans now live in a state where medical marijuana is legal, the post says, citing a Pew Research Center study from February.
Mohab Ibrahim, a physician and the medical director of the Comprehensive Center for Pain and Addiction at the University of Arizona Health Sciences, noted in the NCI post that some evidence shows marijuana can suppress a person’s immune system, especially when used long-term, or interact negatively with other medications, for example increasing drowsiness.
He explained that federal prohibition makes it “challenging to test cannabis products in clinical settings,” the post says in a section about the “cannabis-and-cancer information gap,” noting that Ibrahim and others “said they hope cannabis will eventually be reclassified as a schedule 2 or 3 drug, which would likely open the doors for more studies.”
A series of new studies is putting a spotlight on the growing use of #cannabis among #CancerSurvivors and some of the trend’s downstream effects. Learn more: https://t.co/z1PHwJUSZ0 pic.twitter.com/qz8owNLJA4
— NCI Cancer Control (@NCICancerCtrl) October 16, 2024
Among the research cited in the new NCI post is a series of scientific reports published last month in NCI’s journal JNCI Monographs. The 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.
A main finding of one study led by NCI researchers, for example, is that patients’ “reported use of cannabis since diagnosis varied only slightly by legal status.” Of those surveyed between September 2021 and August 2032, 34.3 percent of patients who resided in states where marijuana was legal reported using the substance, compared to 31.5 percent in medical-only states and 24.7 percent in states where cannabis was illegal.
In all, just under a third (32.9 percent) of patients reported using cannabis, with respondents reporting that they used marijuana primarily to treat cancer- and treatment-related symptoms such as difficulty sleeping, pain and mood changes. The most common perceived benefits “were for pain, sleep, stress and anxiety, and treatment side effects,” the report says.
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. Authors acknowledged that obstacles to incorporating cannabis into cancer treatment remain, however, such as regulatory barriers and the need to determine optimal dosing.
Earlier this year, other 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.
That research, published in the journal BioFactors, looked at minor cannabinoids and multiple myeloma (MM), testing responses in cell models to the cannabinoids CBG, CBC, CBN and CBDV as well as studying CBN in a mouse model.
“Together, our results suggest that CBG, CBC, CBN, and CBDV can be promising anticancer agents for MM,” authors wrote, “due to their cytotoxic effect on MM cell lines and, for CBN, in in vivo xenograft mouse model of MM.”
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.
As a 2019 literature review found, the majority of the studies have also been based on in vitro experiments, meaning they did not involve human subjects but rather isolated cancer cells from humans, while some of the research used 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 earlier this 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 published late last year found that marijuana use was associated with improved cognition and reduced pain among cancer patients and people receiving chemotherapy
While cannabis produces intoxicating effects, and that initial “high” can temporarily impair cognition, patients who used marijuana products from state-licensed dispensaries over two weeks actually started reporting clearer thinking, the study from the University of Colorado found.
Late last year, the National Institutes of Health 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.
Federal courts are also considering two separate lawsuits on legal access to therapeutic psilocybin among cancer patients in end-of-life care.
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