THC-CBD Cannabis Extract Found to Suppress Estrogen Receptor-Positive Breast Cancer Tumors in New Study
- The study found that a whole-cannabis extract with THC and CBD significantly reduced tumor growth in mice with estrogen receptor-positive breast cancer, with the highest dose showing a 75.94% tumor volume reduction.
- Researchers used a 1:6 THC-CBD ratio and administered doses of 2, 10, or 20 mg/kg over 30 days, observing statistically significant tumor shrinkage and lower levels of the tumor proliferation marker PCNA in all cannabis-treated groups.
- Apoptosis-like changes were noted in tumor cells at low and high doses, though further molecular confirmation is required; some liver enzyme elevations suggested possible dose-related liver stress at the highest dose.
- The study’s limitations include small sample size, lack of blinding, and absence of separate THC and CBD testing, and findings currently apply only to mice, not humans, warranting cautious interpretation and further research.
A whole-cannabis extract containing THC and CBD significantly reduced the growth of estrogen receptor-positive breast cancer tumors in mice, according to a newly published preclinical study.
The study, published in Veterinary World, examined a cannabis extract containing THC and CBD at a 1:6 ratio using mice implanted with MCF-7 human breast cancer cells. MCF-7 cells are commonly used to model estrogen receptor-positive breast cancer, one of the most prevalent forms of the disease.
Researchers divided 25 mice into five groups. One received sesame oil as a negative control, one received the chemotherapy drug 5-fluorouracil, and three received oral doses of the THC-CBD extract at 2, 10 or 20 milligrams per kilogram of body weight for 30 days.
Tumor volume increased by an average of 7.34% in the negative control group. In comparison, tumors declined by 35.99% in mice receiving 5-fluorouracil, 51.88% in the low-dose cannabis group, 39.71% in the intermediate-dose group and 75.94% in the high-dose group.
The reduction in tumor volume was statistically significant for all three cannabis doses compared with the negative control. Although all three cannabinoid groups had smaller tumors than the chemotherapy group at the end of the study, only the high-dose group showed a statistically significant improvement over 5-fluorouracil when researchers compared the percentage change in tumor volume.
Tissue analysis also found significantly lower levels of proliferating cell nuclear antigen, or PCNA, in all three cannabis groups compared with both control groups. PCNA is used as an indicator of tumor-cell proliferation, suggesting the extract’s primary effect may have involved slowing the reproduction of cancer cells.
Researchers also observed more tumor cells with physical characteristics associated with apoptosis, or programmed cell death, in the low- and high-dose groups. However, the authors cautioned that additional testing would be needed to confirm apoptosis through molecular mechanisms.
Most blood measurements remained within normal ranges among mice receiving the cannabis extract. However, the high-dose group had substantially elevated levels of the liver enzymes ALT and AST, indicating possible dose-related stress on the liver.
The study was limited by its small sample size, lack of blinding and relatively small tumors. Researchers also did not test THC and CBD separately, measure cannabinoid concentrations in the blood or provide a complete chemical profile of the whole-cannabis extract.
The authors said the findings provide new in vivo evidence that a defined-ratio THC-CBD formulation may have antitumor and antiproliferative effects against estrogen receptor-positive breast cancer. However, the results remain limited to an animal model and do not demonstrate that the treatment would be safe or effective in humans.
The research was conducted by scientists affiliated with Thailand’s National Cancer Institute, Government Pharmaceutical Organization, Ministry of Public Health, Lerdsin Hospital and Chulalongkorn University. It was funded by the Department of Medical Services Fund, while the Government Pharmaceutical Organization supplied the cannabis extract.