Enter cannabis. Plentiful preclinical research suggests that specific cannabinoids, such as CBD, may have anticancer and tumor-inhibiting properties.
But, how does that research translate from the test tube to the human body, an infinitely more complex, dynamic environment?
An October 2020 review from a team of researchers in Bulgaria has summarized the anticancer effects of CBD and laid out a tentative map of the ways CBD could enhance or support conventional cancer treatments.
Their study dives into the effects of CBD on different cancer cells, and explains how, when combined with conventional cancer drugs, CBD may promote a special kind of synergy that improves outcomes.
How does CBD target cancer?
Endocannabinoids, or cannabinoids produced by the body, and the cannabinoids in the cannabis plant both play a role in regulating pathways that affect cancer, including how cancer cells grow, migrate, and spread.
The clinical use of THC is often controversial because of its intoxicating psychoactive effects. CBD, on the other hand, is non-intoxicating, and it’s also a well-tolerated compound with a good safety profile. CBD has been shown to reduce tumor growth and progression in cancers as diverse as breast, lung, and colon cancer.
“A large body of evidence from animal and cell experiments demonstrate the numerous direct anti-cancer effects of cannabinoids, including CBD,” said Dr. Dustin Sulak, an integrative physician, cannabis medicine expert, and founder of Healer.com. “Specifically, CBD rarely causes adverse effects, can provide substantial relief on its own, and is especially useful as an adjunct to THC,” he said.
Researchers have now started digging deeper into how CBD might work synergistically with common chemotherapy drugs, and how this potent cannabinoid can be transitioned out of the laboratory and into the treatment room.
The effects of CBD on different kinds of cancer
In the 2020 review study from Bulgaria mentioned above, the research team explored the evidence supporting the use of CBD in the treatment of diverse types of cancer. Here are their findings on the three most common forms of the disease:
CBD has an inhibitory effect on breast tumor cells, specifically the MCF-7 cell line, which is frequently used in research on cancer treatment drugs. Researchers found that CBD exerts a more powerful action in halting the spread of breast cancer cells compared to other cannabinoids.
Research carried out in 2012 found that CBD exerts a mechanism that prevents the spread of lung cancer tumors. The same research team also reported that CBD encourages cancer cell death in primary lung tumor cells.
Test tube experiments on different prostate cell lines have shown that CBD decreases androgen receptor expression, which strongly influences the development and progression of prostate cancer. Inhibiting the activity of these receptors may delay prostate cancer progression.
CBD to inhibit tumor growth and spread
One of cancer’s most problematic characteristics is the spread of cancerous tumors throughout the body. Unlike regular healthy cells, cancer cells express a number of mutations that prevent cellular death. These mutated cells can then spread and colonize multiple other sites in the body.
Cancer research often focuses on the primary place a cancer originated and not the secondary sites where it has spread to. Fascinatingly, investigations into cannabinoids like CBD often focus on its ability to inhibit the progression of cancer cells that have already migrated and begun forming new tumors.
According to the Bulgarian research review, CBD acts on a number of pathways in the body to encourage tumor suppression. One of the most significant ways CBD may slow tumor progression is via its modulation of the PI3K pathway, a major pathway that modulates cell growth, metabolism, survival, and spread, and therefore represents a target for cancer treatment.
How CBD can be combined with cancer therapies
According to the Bulgarian review, a number of reports advocate for combination therapy approaches. Combining CBD with specific anticancer drugs has already shown to render certain cancer cells more vulnerable to the effects of cancer drugs.
In pancreatic cancer patients, other landmark research has demonstrated that CBD in conjunction with chemotherapy can yield promising outcomes, a type of cancer notorious for being treatment resistant. Mice with pancreatic cancer lived nearly three times longer when a conventional cancer treatment, gemcitabine, was combined with CBD. In addition to extending lives, CBD could enhance quality of life too.
Another study has shown that CBD and conventional treatment temozolomide can be combined to treat gliomas—brain and spinal cord tumors—more successfully.
CBD for cancer therapy side effects
There’s also plentiful research supporting CBD as an adjunctive drug that prevents and reduces the side effects of cancer therapies. One of the most unpleasant effects of hard-hitting cancer drugs is peripheral neuropathy, which causes weakness, numbness, and pain in the hands and feet. Up to 75% of patients can experience this as a result of certain chemotherapy regimens.
CBD can help prevent the development of this sensitivity. According to a 2014 study in mice, CBD doses administered before paclitaxel, a form of chemotherapy, prevented the development of nerve sensitivity in mice. Importantly, the nervous systems of the mice were unharmed and chemotherapy efficacy wasn’t compromised by the treatment.
Another investigation has shown that CBD can support the kidneys and decrease kidney toxicity induced by cisplatin, a chemotherapy agent linked to kidney damage.
Does the future of cancer treatment include CBD?
Like many nascent fields of cannabis science, the data exploring CBD and cancer treatments is currently limited. What the 2020 Bulgarian review lays out, however, is a body of evidence indicating the diverse ways CBD can support cancer treatments—and the need for more comprehensive clinical investigations to test its efficacy.
“This review concisely summarizes the data on CBD’s ability to inhibit a variety of cancers and to act synergistically with conventional anticancer treatments,” said Dr. Sulak. “While we have a lot to learn about how to maximize these potential benefits in our human patients, the impressive safety, tolerability, and symptomatic benefits of CBD make a strong case for its use by patients with cancer.”