CBD + CBC (or THC) worked best on head & neck cancer cells

This research examined the anti-tumor effects of 24 different types of cannabis extracts on head and neck squamous cell carcinoma (HNSCC) cancer cells. It was published in the journal Cancers in January 2023. 

The study used four "well-characterized human adherent epithelial cancer cell lines" for their in vitro tests - not in humans or animals, but on cell cultures. They tested extracts with both acidic and neutral (decarbed) cannabinoids.

Extracts were classified into three groups:

1. THC-type with high THC (~50% w/w) and low CBD concentration (<1% w/w)
2. CBD-type with high CBD (~50% w/w) and low THC concentrations (<3% w/w)
3. THC:CBD group with equal (~30% w/w) THC and CBD concentrations. 

The results show that the extracts dominant in the acidic cannabinoids (THC-A, CBD-A, CBG-A, etc.) did not perform as well as the extracts dominant in neutral, "decarbed" cannabinoids (THC, CBD, CBG, etc.). The data collected indicated neutral cannabinoid extracts were more than twice as effective at killing cancer cells.

extracts of the decarboxylated CBD-type significantly decreased the cell viability of all four cell lines.

The most effective unmodified extract had the following major cannabinoid profile:

The authors then experimented by changing the dominant cannabininoid in several extracts by adding a cannabinoid isolate consisting of almost pure CBD, THC, CBDV, or CBC. They wanted to determine the cannabinoids most responsible for cell death (or apoptosis - cells killing themselves).

They found "a synergy correlation between CBD/CBC (synergy score, 28.01) at a 2:1 concentration ratio and between CBD/THC (synergy score, 15.41) at a 4:3 concentration ratio". Synergy is the scientific term for the "entourage effect" of several active ingredients combined together showing more effectiveness than a single active ingredient by itself. 

In summary, 2:1 CBD:CBC and 4:3 CBD:THC were shown to be most effective at decreasing the viability of head and neck squamous cell carcinoma cancer cells. 

Conclusions in the authors' words: 

decarboxylated extracts with high levels of Cannabidiol (CBD) were the most effective in killing cancer cells

The cytotoxic effect could be maximized by combining CBD with either CBC or THC in a ratio of 2:1. 

This research suggests using decarboxylated CBD-type extracts enriched with CBC for future preclinical trials aimed at HNSCC treatment.

The full text article is here at MDPI.com.