The fact that both the THC isolate and the whole plant cannabis extract were shown to be effective at reducing tumor viability is truly groundbreaking and should be an impetus for advancing the development of nontoxic, cannabinoid-based treatments for breast cancer.
When the cannabinoid preparations were added to tamoxifen, a standard chemotherapy drug, in a cell plate, the combined therapy was about 20-25% more effective than chemotherapy alone. But these results were not replicated in live-animal trials. Importantly, the cannabinoids also did not negatively impact the efficacy of the chemotherapy. This suggests that at the very least using cannabis as an add-on treatment to deal with common side effects of chemotherapy, like nausea and appetite loss, won’t impede chemotherapy’s ability to destroy cancer cells.
The vast majority of this preclinical research has examined the anticancer activity of pure compounds, mainly THC isolates. But medical cannabis patients aren’t using pure, single-molecule THC to battle cancer. Instead, they are consuming whole plant cannabis oil extracts that include hundreds of compounds, many of which also have therapeutic properties. These artisanal cannabis oil preparations are available in licensed dispensaries in states where medical cannabis is legal and elsewhere via the unregulated black market.
THC & Triple-Negative Breast Cancer
CB2 actually conjoins with HER2 – forming what is called a dimer – and this dimerization is associated with poor treatment outcome for breast cancer. The PNAS report shed new light on THC ’s anticancer mechanism of action: When THC binds to the CB2 receptor, it breaks up the CB2 – HER2 dimer, triggering a chain reaction of signals that culminates in tumor regression.
Triple-negative, the breast cancer subtype with the worst prognosis, does not generally respond well to chemotherapy. But the Spanish group found that THC and THC -rich cannabis oil both offer some hope in improving treatment outcomes for this highly aggressive cancer. Again, the whole plant extract was found to be more effective than THC alone in decreasing the viability of cancer cells in vitro as well as in mouse model studies.
Alex Andia, who holds his PhD in Chemistry, teaches Organic Chemistry at the City University of New York – City College. He is also the brains behind Chemical Makeup, a non-profit dedicated to promoting the queer voice in science.
As with hormone-sensitive breast cancer, THC ’s antitumoral effect in HER2 -positive breast cancer experiments was shown to be mediated by the CB2 cannabinoid receptor. Published in the Proceedings of the National Academy of Science, a subsequent report by Cristina Sanchez and other Spanish scientists noted that HER2 and CB2 receptors are often found in the same exact place on cells.
If you’re taking certain medications like blood thinners and thyroid and seizure medications, you’ll need periodic blood tests to make sure your levels are where they should be. If you’re on a medication like this and you’re going to use CBD products, Mathias Schmucki says, your doctor will need to monitor you to make sure your levels stay on track. “Everybody’s different, so you won’t really know how CBD will affect your body’s metabolism of other medications,” she says.
“Research on medical cannabis products, including CBD oil, has been limited because federal laws in the United States have made it difficult to study,” Weiss says. But now that hemp production is legal, it can be studied, Mathias Schmucki notes. “Lifting federal regulations off of the growing and scientific study of cannabis plants will help over time in answering some of these questions about areas like safety, dosing, and contraindications,” she says.
Side Effects and Risks
Project CBD: “Is CBD Really Non-Psychoactive?”
“As a doctor, I make the distinction between complementary and alternative medicine,” says Andrea Mathias Schmucki, MD, a patient advocate for the Living Beyond Breast Cancer Hear My Voice advocacy program and a former family physician. She is herself being treated for metastatic breast cancer, or cancer that’s spread to other parts of her body. “I look at CBD as complementary, using it in addition to, rather than as an alternative to, traditional treatment.”
Weiss offers these cautions: