Will cannabis for breast cancer be a mainstream treatment of the future?
A new animal study shows CBD may inhibit metastasis in breast tissue. This means that CBD may potentially regulate breast cancer cells. Moreover, multiple studies are beginning to show how science could potentially utilize the cannabis plant for breast cancer treatment.
Though many of these studies are preliminary, collectively they point the way for further research and human trials. From treatment for cancer-related pain, to potential anti-cancer capabilities, cannabis studies are providing results that may change what we know about cancer.
According to breastcancer.org, “In 2020, an estimated 276,480 new cases of invasive breast cancer are expected to be diagnosed in women in the U.S., along with 48,530 new cases of non-invasive (in situ) breast cancer.” And approximately one in eight women will develop an invasive form of breast cancer in her lifetime. For women, breast cancer is deadly — about 42,170 women in the U.S. are expected to die from it this year.
The disease is notoriously difficult to treat once it has metastasized and proliferated throughout the body’s tissue. That’s why any scientific advances toward treating this late-stage of cancer can have an enormous impact. And through these early studies, we’re seeing what might be possible with the utilization of cannabis for breast cancer treatment.
Cannabis For Late-Stage Cancer Progression
In a study published in Molecular Cancer Therapeutics (2007), scientists discovered how CBD could potentially inhibit the progression of breast cancer, and possibly even during later stages. They used human cancer cell cultures to find that CBD could down-regulate expression of the Id-1 gene, which is a pro-metastatic gene. By doing so, CBD could potentially inhibit the invasiveness of cancer cells and slow down the growth of tumors.1)McAllister, Sean, et al. Cannabidiol as a Novel Inhibitor of Id-1 Gene Expression in Aggressive Breast Cancer Cells. Molecular Cancer Therapeutics, 2007, mct.aacrjournals.org
These findings were then later supported in another study published in Breast Cancer Research and Treatment (2011). Through an experiment in mouse models, scientists concluded that CBD inhibits cancer cell proliferation through modulation of the extracellular signal-regulated kinase (ERK), as well as reactive oxygen species (ROS) pathways. And what do those pathways lead to? Down-regulation of the Id-1 gene.2)McAllister, S.D., Murase, R., Christian, R.T. et al. Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis. Breast Cancer Res Treat 129, 37–47 (2011). https://doi.org/10.1007/s10549-010-1177-4
CBD’s non-toxic approach to down-regulating the expression of Id-1 makes it an even more promising candidate for development. The side effects are low — which is meaningful, since patients suffering from breast cancer are also experiencing a weakened immune system.
It’s possible that CBD might also inhibit metastasis by blocking angiogenesis. A review study published in the Journal of Neuroimmune Pharmacology (2015) described how CBD could inhibit the vascular endothelial growth factor (VEGF) pathway, preventing the tumor from forming new blood vessels.3)McAllister, et al. The Antitumor Activity of Plant-Derived Non-Psychoactive Cannabinoids, Journal of Neuroimmune Pharmacology. DeepDyve, Springer US, 28 Apr. 2015, www.deepdyve.com/lp/springer-journals/the-antitumor-activity-of-plant-derived-non-psychoactive-cannabinoids-cmxY2L7Aev
Other Useful Compounds in Cannabis
While CBD has given researchers more reasons to continue to learn about cannabis for breast cancer, THC has also shown promise. In a study published in the Proceedings of the National Academy of Sciences of the United States of America (2019), scientists tested THC on HER2 positive breast cancer lines in vitro. They found that THC can diminish the number of CB2 receptors binding with HER2, and that it can also block HER2 activation. These results point toward a possibility of using THC to fight tumor growth.4)Blasco-Benito S., et al. Therapeutic Targeting of HER2-CB 2 R Heteromers in HER2-Positive Breast Cancer. Proceedings of the National Academy of Sciences of the United States of America, U.S. National Library of Medicine, 2019, pubmed.ncbi.nlm.nih.gov/30733293/
Researchers have also found that synthetic cannabinoids could potentially fight breast cancer. In a study published in Molecular Cancer Therapeutics (2009), scientists showed that human breast cancer tumors exhibit an over-expression of CB1 and CB2 receptors. Using synthetic cannabinoids JWH-133 and WIN-55,212-2, they inhibited the spread of cancer cells in vitro and in vivo using mouse models.5)Qamri, Zahida, et al. Synthetic Cannabinoid Receptor Agonists Inhibit Tumor Growth and Metastasis of Breast Cancer. Molecular Cancer Therapeutics, U.S. National Library of Medicine, Nov. 2009, www.ncbi.nlm.nih.gov/pmc/articles/PMC4128286/
The results were impressive, as the mice treated with these synthetic cannabinoids experienced a forty to fifty percent reduction in tumor growth. To further prove the effectiveness of CB1 and CB2 agonists, researchers reversed the effects through utilization of CB1 and CB2 synthetic antagonists.
The discovery that CB1 and CB2 receptor signaling can influence tumor growth is an important one for breast cancer. Though receptor expression can change among different forms of cancer, including different subtypes of breast cancer, affecting this expression could be a game-changer for a significant portion of breast cancer patients.
Future Considerations for Cannabis and Breast Cancer
Together, these studies show us that further research into the effects of cannabis on breast cancer is warranted. So far, many of these studies have been preliminary, with results garnered from in vivo and in vitro studies. However, in the United States, gaining access to cannabis continues to be an obstacle for scientists.
Researchers in the U.S. have also experienced road blocks to running human trials with cannabis. Synthetic cannabinoids have shown some promise. But, they lack the presence of the many other compounds present in the cannabis plant. And these are compounds that might have something to offer.
Though other countries are making headway in this research, current restrictions in the United States have a significant impact. More human trials are needed in order to gain a more accurate understanding of how cannabis can work with the endocannabinoid system for breast cancer.
References [ + ]
|1.||↑||McAllister, Sean, et al. Cannabidiol as a Novel Inhibitor of Id-1 Gene Expression in Aggressive Breast Cancer Cells. Molecular Cancer Therapeutics, 2007, mct.aacrjournals.org|
|2.||↑||McAllister, S.D., Murase, R., Christian, R.T. et al. Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis. Breast Cancer Res Treat 129, 37–47 (2011). https://doi.org/10.1007/s10549-010-1177-4|
|3.||↑||McAllister, et al. The Antitumor Activity of Plant-Derived Non-Psychoactive Cannabinoids, Journal of Neuroimmune Pharmacology. DeepDyve, Springer US, 28 Apr. 2015, www.deepdyve.com/lp/springer-journals/the-antitumor-activity-of-plant-derived-non-psychoactive-cannabinoids-cmxY2L7Aev|
|4.||↑||Blasco-Benito S., et al. Therapeutic Targeting of HER2-CB 2 R Heteromers in HER2-Positive Breast Cancer. Proceedings of the National Academy of Sciences of the United States of America, U.S. National Library of Medicine, 2019, pubmed.ncbi.nlm.nih.gov/30733293/|
|5.||↑||Qamri, Zahida, et al. Synthetic Cannabinoid Receptor Agonists Inhibit Tumor Growth and Metastasis of Breast Cancer. Molecular Cancer Therapeutics, U.S. National Library of Medicine, Nov. 2009, www.ncbi.nlm.nih.gov/pmc/articles/PMC4128286/|