In our previous article “Can Cannabis Kill Cancer?”, we highlighted research that establishes evidence of the anti-cancer properties of THC and CBD (the most active compounds) or cannabinoids naturally occurring in cannabis.
Where much of the research of the past decade has focused on the success of individual cannabinoids to reduce and inhibit tumor growth, the most recent investigation has found a far greater effect through a combination of THC and CBD in concert with radiation treatment.
THC & CBD with Radiation Therapy – the One-Two Punch on Glioma
In a 2014 study published in Molecular Cancer Therapeutics, researchers from St. George’s University of London uncovered “dramatic reductions” in high-grade glioma masses – a deadly form of brain cancer – when THC and CBD were used in conjunction with radiation treatment, or radiotherapy, on mice. This study was the first to document the effects of cannabinoids on cancer when used with radiotherapy.
Dr. Wai Liu, one of the study’s lead authors, wrote about the significance of this groundbreaking research for the Washington Post. He and his team made several important findings:
‘A low dose of THC and CBD together was just as effective as a high dose of either compound in killing cancer cells and had the best overall effect, especially because it reduced the unwanted side effects of overexposure to THC.
Irradiation as the sole treatment had little effect on tumor growth. THC and CBD administered together marginally reduced it. The combination of both cannabinoids with irradiation had the greatest effect and stopped tumor growth during the course of treatment.’
Just as in a one-two punch, it is thought that because THC and CBD work on different pathways in the body, using them together “primes” tumor cells and makes them “more sensitive to the ‘cell killing’ effects of radiation,” Dr. Liu told Medical Daily.
As a result, tumor sizes were significantly smaller on the final day of treatment with subjects who had received the “triple threat” of irradiation coupled with THC and CBD compared to the control group. As the Huffington Post reported, the tumors had shrunk to as low as one-tenth the sizes of those in the control group in many cases.
Given the very low long-term survival rates for glioma patients – only 10% survive the first five years – Dr. Liu is optimistic about the results. He writes, “… it could provide a way of breaking through glioma and saving more lives.”
Dr. Liu also told HuffPost, “The results showed that the final effect was superior to the sum of the parts.”
The Synergy of Cannabis with Cancer Treatments
Jahan Marcu, Ph.D., Director of Research and Development of Green Standard Diagnostics, a lab that tests safe uses of medical marijuana, calls this effect synergy.
In his article as science editor of Freedom Leaf, the magazine of an organization by the same name that supports the marijuana legalization movement, Dr. Marcu writes, “combining CBD and THC with conventional treatments may be the best synergy for cancer sufferers.”
In addition to the St. George’s University study, Dr. Marcu cites several other studies that have achieved success in experimental models with combining cannabinoids and conventional cancer treatments.
The synergistic effects on cancer that Dr. Marcu and other cannabis researchers note function in two ways.
First, there is the synergy between THC and CBD documented in past research. CBD has been observed to enhance THC’s medicinal benefits while reducing its anxiety-producing and intoxicating effects. At the same time, CBD, having anti-cancer properties in its own right, complements THC by acting on different pathways.
Second, the interaction of THC and CBD with radiation or chemotherapy treatments produces its own synergy. Dr. Liu found that exposure to cannabinoids primed or sensitized cancer cells to the effects of irradiation. For Dr. Marcu, it is the other way around – chemotherapy and radiotherapy make cancer cells much more sensitive to THC and CBD.
Either way, Dr. Marcu concludes that because of the way cancer cells adapt, change, and mutate to extremes, making them resistant to treatment through both conventional therapies and cannabis when taken alone, “the best bet is combining cannabis-based preparation with conventional treatment for cancer.”