CBD and CBC Can Kill Head and Neck Cancer Cells, Study Finds
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Cannabis extracts that are high in CBD can kill head and neck cancer cells, a new study has found.
Published in Cancers, the study looked at the anti-tumor effects of 24 unique cannabis extracts on head and neck squamous cell carcinoma (HNSCC). The researchers found that CBD-dominant extracts could induce apoptosis and kill these cancer cells. Combining CBD with cannabichromene (CBC) in a 2:1 ratio made this effect even stronger.
The researchers say that further research is still needed before developing products based on these findings. However, they believe their study suggests that the cannabis extracts already used in palliative care to help with symptom management may be providing an additional, previously unknown anti-cancer effect.
Extracts high in CBD cause cancer cell death
HNSCC is the sixth-most common cancer worldwide and accounts for more than 90% of the cancers of the head and neck. Despite its prevalence, and significant advances being made in cancer screening and prevention over the past several years, HNSCC is still thought to be responsible for around 450,000 deaths worldwide each year.
Cannabinoids are one of several compounds that are currently being investigated as a novel therapy for a variety of cancer types. In this new study, the researchers tested and compared the cytotoxic effect of 24 different cannabis extracts on HNSCC cells in a cell viability assay. The cannabinoid profile of each extract was also determined using electrospray ionization liquid chromatography-mass spectrometry (ESI-LC/MS).
The researchers found that decarboxylated CBD-dominant extracts caused a significant increase in cell death across all HNSCC cell lines that were tested. This relationship also appeared to be dose-dependent, with a greater percentage of cells dying when higher concentrations of extract were applied. Using western blot analyses, the researchers confirmed that this cell death was a result of the extracts inducing apoptosis.
The researchers also ran a second batch of cell assays, this time using a non-cancerous human fibroblast cell line. In these experiments, there appeared to be no significant changes to cell death rates when the lines were exposed to the extracts. This would suggest that the anti-tumor effect of the CBD-dominant extracts is selective to HNSCC cancer cells.
CBD and THC may enhance this effect
To determine exactly which components of the CBD-dominant extract may be responsible for this anti-tumor effect, the researchers used liquid chromatography to separate the best-performing extract out into four fractions, which were each separately characterized using ESI-LC/MS and ultra-high-performance liquid chromatography with an ultraviolet detector (UHPLC-UV).
The resulting four fractions each had a different cannabinoid as its major constituent, either being dominant in CBD, cannabidivarin (CBDV), THC, or CBC.
The researchers found that the CBD-dominant fraction was able to kill a significant portion of the cancerous HNSCC cells. However, it was notably less potent at doing so than the unfractionated extract had been.
When the CBD fraction was combined with either the CBC fraction or the THC fraction, the effect on the cancer cells increased to match that of the whole extract. The researchers also determined that a combination of CBD-CBC or CBD-THC fractions in a 2:1 ratio were the most potent in terms of their cytotoxicity.
“Yet, it is not clear whether the cytotoxic effect of CBD and CBC combination is the result of one cannabinoid enhancing the activity of the other or from hitting different signaling pathways at once,” the researchers wrote.
While more research is still needed to determine how such extracts bring about apoptosis, the researchers point out that medical cannabis is already in use in many areas as a palliative treatment for cancer patients.
“Based on this research, these chemovars can provide additional anti-cancer properties in addition to the palliative effects that cancer patients can benefit from,” they wrote. “Furthermore, we recommend enriching extracts with CBC to reach a CBD to CBC ratio of (2:1) to maximize the cytotoxic effect on HNSCC.”
Cannabis and cancer
While these results are promising, other studies urge caution when it comes to the beneficial aspects of cannabis for cancer patients.
For example, a 2020 study published in Clinical Cancer Research suggested that cannabis use may actually be a driving factor in the rising prevalence of head and neck cancer cases. The researchers found that THC may activate a certain molecular mechanism in the body that can accelerate tumor growth in patients with human papillomavirus-positive head and neck cancers.
More studies of cannabis flower and cannabinoid extracts will be essential to fleshing out the current scientific understanding of how cannabis and cancer cells interact. While some medical cannabis preparations such as nabilone are already licensed for treating certain side effects of cancer chemotherapy, a small but alarming trend of some individuals abandoning traditional cannabis treatments in favor of cannabis-based products has caused concern among medical professionals.
“I write on whether oncologists should recommend cannabis and I'm a very strong proponent of it, because a day doesn't go by that I don't see a cancer patient with nausea, loss of appetite, pain, insomnia, depression, and I can recommend one medicine to those patients,” Donald Abrams, a doctor and professor of clinical medicine at the University of California, San Francisco, told Analytical Cannabis in 2019.
“What pains me is people forgoing conventional therapy that may benefit them greatly and even cure them, in favor of using these products that have absolutely no evidence to support their use,” he continued. “And in San Francisco, patients pay up to $7,000 a month for these products. I just find it criminal and tragic.”
“As an oncologist in San Francisco for the past forty years, I have to say, if cannabis cured cancer, I would certainly have a lot more survivors.”