Cannabidiol (CBD) Treatment May Fight Breast Cancer, Researchers Say

Researchers in the U.S. are developing new treatments for breast cancer based on compounds found in Cannabis.

For nearly a decade, a group of scientists at the California Pacific Medical Center Research Institute have been studying the cancer-fighting potential of marijuana’s ingredients.

Belonging to a family of compounds known as cannabinoids, the active ingredients in marijuana, which include THC (tetrahydrocannabinol) and CBD (cannabidiol), have been shown to combat the growth and spread of tumors in various cancer models.

The team’s latest findings, published online in the British Journal of Pharmacology, suggest that both plant-derived and synthetic cannabinoids may hold promise in treating breast cancer.

“We determined that CBD was effective at inhibiting metastatic progression”

“In this investigation, we determined that CBD was effective at inhibiting metastatic progression leading to prolonged survival in multiple preclinical models of breast cancer,” wrote Sean McAllister, PhD, the study’s lead author.

In one mouse model, treatment with cannabidiol was found to reduce breast cancer metastasis by up to 75%. Although THC was not tested, the team notes, previous research has demonstrated its antitumor activity “against a variety of aggressive cancers.”

But the group’s findings also seem to suggest that neither compound alone is the most effective therapy.

Searching for an even more potent compound, the researchers performed experiments with a synthetic cannabinoid called O-1663. In comparison, O-1663 was found to be “significantly more potent and efficacious than CBD.” 

Interestingly, O-1663 seems to activate the same cancer-fighting pathways as THC and CBD do on their own.

“In agreement with this hypothesis, the combined administration of CBD and THC produced a similar magnitude of anti-metastatic activity when compared to O-1663 alone,” wrote Dr. McAllister and his team.

Studies show that THC’s anti-cancer effects occur through pathways known as cannabinoid receptors (CB1 and CB2). These pathways, while expressed by various cells in the body, are found in tumor cells at abnormally high concentrations.

Activation of CB1 and CB2 receptors has been shown to initiate a number of mechanisms leading to tumor cell death, while leaving healthy cells unharmed.

“THC and CBD… have anti-inflammatory, analgesic and neuroprotective effects”

Cannabidiol, on the other hand, does not directly bind to cannabinoid receptors. Rather, CBD’s anti-cancer effects seem to stem from its ability to target the ID1 gene — a known player in the metastasis of numerous cancers, including breast cancer.

Still, while O-1663 appears to hold more promise as a cancer treatment than either CBD or THC individually, the authors note that other benefits have been attributed to the plant-based compounds.

“THC and CBD have been shown to have anti-inflammatory, analgesic and neuroprotective effects,” they explain. Medical marijuana, in various forms, can also be used to manage symptoms of appetite loss and nausea.

The researchers conclude that more studies are needed to identify the mechanisms underpinning THC and CBD’s broader benefits and whether O-1663 can offer the same.