Cannabis Is Critical to Cancer Treatment But How Much Do You Need?
There is a significant difference in the dose needed to treat the side effects of cancer treatment and that needed to kill cancer cells.
Between 30% and 90% of chemotherapy recipients experience nausea and vomiting associated with cancer treatment. It can occur at any point before (anticipatory), or immediately after (acute, within 24 hours) or even after the first 24 hour (delayed).
Repeated episodes of vomiting could become detrimental in individuals who are already substantially compromised, such as cancer patients, as the risks of dehydration and electrolyte imbalance are too great. The therapeutic need for antiemetics and pain relief associated with cancer and available chemotherapy agents is still unmet.
Cannabis Stops Nausea and Vomiting
According to the recent meta-analysis, there are 28 studies evaluating the therapeutic potential of cannabinoids in treating nausea and vomiting associated with chemotherapy. Cannabinoids used ranged from THC and THC-like compounds, nabilone and dronabilone, to a mix of THC and CBD in 1:1 ratio. The doses for THC ranged from 5-60mg per day, while the combined THC:CBD were administered in form of a spray containing 27mg and 25mg of each, respectively.
All studies suggested that the number of patients showing complete alleviation of nausea and vomiting was greater in groups using cannabinoids in any formulation. The patients were 4 times more likely to experience this positive effect if they were using cannabinoids.
Cannabis Relieves Cancer Pain
Chronic pain alleviation with cannabinoids has been assessed in more than 2,000 cancer patients to date. Most of the patients experienced improvements in pain measures when using cannabinoids, either as smoked THC (1-5 cigarettes/day) or as a THC:CBD spray (27mg and 25mg/millilitre, respectively). The average number of patients experiencing reduction in pain (of at least 30%) was greater in the cannabinoids group compared to placebo.
One study reported that smoked THC exerted the greatest benefit, and patients reported over 3-fold improvement in pain.
Cannabis Helps with Sleep
Furthermore, there is evidence that cancer, cancer treatments, and their side effects are associated with insomnia and poor quality of sleep. Although the therapeutic potential of cannabis and cannabinoids-based therapies have not been directly evaluated in cancer patients, reports describing beneficial effects exist for other patient populations.
THC-like compound nabilone was associated with improvements in insomnia and greater sleep restfulness in fibromyalgia patients. Furthermore, 11 additional trials found a positive association between using cannabinoids either as THC or CBD alone, or in combination and improvement in sleep quality, and the results were similar for all cannabinoids. So, you can imagine how much more effective the plant will be.
Cannabis Kills Cancer Cells
Recent investigations have shown that activation of cannabinoid-based signaling can also kill cancer cells, and thus prevent further spreading. Besides these antiapoptotic and antiproliferative actions, it has also been demonstrated that cannabinoids can stop the spread of cancer cells dead in their tracks by attacking other aspects of cancer progression.
The first step that a collection of cancer cells has to do to survive is establish blood supply with the host, a process called neovascularization. It has been shown by one of several studies that activation of CB1 and CB2 receptors by THC prevents the host’s blood vessels from establishing connection with cancer cells. The second plan of attack of cancer is to enable cancer cells to move, a process called cellular migration, which is arguably the most important step for cancer spreading. To spread into other tissues, the primary cancer cells have to enter either the lymphatic or blood vessels.
Several studies investigating glioma and cervical cancers have identified reduced migratory potential of cancer cells in vitro with CB1 receptor activation. Further, the invasiveness of cancer is dependent on its ability to degrade the surrounding tissue such that the cancer cells can grow and move, a process requiring a set of important matrix degrading enzymes called matrix metalloproteinases.
Cannabis Decreases Invasiveness of Cancer
CBD and THC have been shown to decrease invasiveness of breast, lung and cervical cancer. If the primary tumor succeeds through neovascularization, migration and invasion it leads to metastasis, which is the transfer of malignant cells from one area to distant organs, and is one of the most frequent reasons for death of cancer patients. CBD-rich extracts have been shown to shut down the signaling cascades that enable breast cancer cells to metastasize, and THC has been implicated in inhibiting crucial pathways to metastasis of lung cancer.
Dosing: How Much Do You Need to Kill Cancer Cells?
The main difference in studies examining cannabinoid-based treatments of cancer-associated side effects and cancer itself lies in the dose. For example, most studies exploring the effects of THC and CBD on cancer cell death, and prevention of migration, invasion and metastases employ concentrations in the micromolar range. How does that translate to the concentrations in the blood after consuming cannabis?
According to the pharmacokinetic parameters of THC, ingestion of 10mg of THC results in concentration of THC of 32 nanomolar in whole blood. That is roughly a hundred to a thousand-fold less than what is used in the in vitro studies that result in cancer cell death. This doesn’t necessarily mean that this relationship is linear, and that one would need to consume a thousand-fold more to achieve cancer-killing concentrations.
The safety and efficacy profile of consuming cannabis in amounts that would yield micromolar concentrations in blood has not been investigated. Perhaps the future lies in devising a strategy for site-specific delivery of THC and CBD at these relevant higher concentrations, only to the tumor microenvironment.