Cancer is a leading cause of death around the world. It is estimated that 1,735,350 new cancer cases will be diagnosed in the United States in 2018. Around 609,640 people will die from the disease. The National Institute of Cancer predicts that death toll will increase by 60% by the year 2030 [R]
At some point in their lives, almost 40% of Americans will be diagnosed with cancer. You probably know someone who has battled cancer. [R]
CBD is the hottest thing in the health and wellness field right now. Short for cannabidiol, CBD is an extract from the cannabis plant. It is usually mixed with carrier oil, such as MCT coconut oil, and taken as a supplement.
Unlike the more popular cannabis extract THC, cannabidiol does not have mind-altering effects. When extracted from industrial hemp, CBD is completely legal in the United States.
What are cannabinoids?
Cannabis has been around for thousands of years. As far back as 3,000 years ago, people have been using cannabis for medicinal purposes. Modern medicine is just beginning to explore the effects of CBD in pain relief, inflammation, convulsions, and anxiety.
Scientists have identified active components in the cannabis plant known as cannabinoids. The two most studied cannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). When cannabinoids activate specific receptors in the human body, they produce pharmacologic effects particularly in the central nervous system and the immune system.
Cannabinoids have been studied in the laboratory and the clinic for relief of pain, nausea and vomiting, anxiety, and loss of appetite – major side effects of cancer and cancer treatment. [R]
Cannabinoids might also help:
- Reduce inflammatory
- Block malignant cell growth
- Prevent the growth of blood vessels that supply blood to tumors
- Produce anti-viral effects
- Relieve muscle spasms from multiple sclerosis
The US Food and Drug Administration (FDA) has already approved two cannabis-based drugs for medical use.
Dronabinol (Marinol®) is a gelatin capsule that contains THC. It is prescribed for nausea and vomiting caused by chemotherapy. It can also help improve appetite and prevent weight loss in AIDS patients.
Nabilone (Cesamet®) is a synthetic cannabinoid that is similar to THC. It is also prescribed for nausea and vomiting caused by chemotherapy when other drugs are not working.
A third possible cannabinoid drug is Nabiximols (Sativex®) which is currently under review in the US. This mouth spray contains a one to one ratio of whole-plant THC and CBD extracts. Sativex® is already available in Canada, Australia, the United Kingdom, Spain and 25 other countries for the treatment of cancer pain and muscle spasms from multiple sclerosis.
CBD and the endocannabinoid system
In the mid-1990s, Israeli organic chemist Dr. Ralph Mechoulam discovered the endocannabinoid (EC) system which is present in all humans and some animals as well. A professor at Hebrew University in Jerusalem, Dr. Mechoulam was the first scientist to isolate THC in the early 1960s. He is often referred to as the Grandfather of Marijuana after spending a long career on cannabis research.
The EC system is a network of receptors that affect appetite, mood, memory and more. These receptors are configured only to accept cannabinoids, which is why cannabis-based therapies work so efficiently.
Dr. Mechoulam discovered two main receptors: CB1 and CB2.
CB1 receptors are primarily found in the brain. According to research, THC is specifically cued to CB1 which explains the feeling of intoxication. From a therapeutic standpoint, CB1 is important in modulating and moderating the perception of pain. For example, when you touch a hot stove, your brain tells you that it is hot so you pull your hand away. THC reduces the intensity of this pain when it is present in the CB1 site. CB1 receptors are not present in the part of the brain that regulates heart rate and respiration, so there is no lethal dosage threshold unlike narcotics.
The other cannabinoid receptor – CB2 – is primarily found in the immune system. CBD is keyed to CB2 and works as an anti-inflammatory agent. CBD also has anti-spasmodic qualities and is said to be able to knock THC off the CB1 receptor to counteract the high. Research on CBD is fairly new but the future of CBD-rich medicines looks very promising. [R]
Although THC and CBD are the most talked about cannabinoids, there are dozens more that have been identified and are currently being studied. Cannabigerol or CBG binds to both CB1 and CB2 receptors and is an antagonist to CB1. Cannabichromene or CBC has anti-inflammatory and analgesic properties. Tetrahydrocannabivarin or THCV is another cannabinoid that acts as a THC antagonist.
CBD and cancer
Dr. Cristina Sanchez, a microbiologist at Compultense Univeristy in Madrid, has been studying cannabinoids and cancer since the turn of the century. She was the first to explore the anti-tumor effects of these compounds.
According to Dr. Sanchez, one of the advantages of cannabinoid-based medicines over traditional therapy is that they target specific tumor cells. They will not kill healthy cells unlike standard chemotherapy that targets everything.
In a laboratory setting, cannabinoids that were administered to treat astrocytoma killed the tumor cells in the Petri dish. Cannabinoids were also analyzed in animal models of breast tumors. The results showed that cannabinoids may be useful for the treatment of breast and brain cancer.
The potential of CBD as an anti-cancer agent has long intrigued scientists because of its ability to interfere with cellular growth in tumors. In vitro studies and animal-based trials conducted by researchers at the California Pacific Medical Center have shown that CBD may help shut down cellular growth receptors in aggressive metastasis. CBD is also able to activate apoptosis, or programmed death of cancer cells.
Can CBD cure cancer?
No, there is no scientific evidence that CBD or other cannabinoids can actually cure cancer.
Dr. Donald Abrams, chief of the Hematology-Oncology Division at San Francisco General Hospital, consultant at the UCSF Osher Center for Integrative Medicine, and one of the leading cancer researchers in the world, says the term "cure" in oncology implies that the patient has survived five years without evidence of cancer.
In a comprehensive review of cannabis literature, researchers from the National Academies of Sciences, Engineering and Medicine (NASEM) did not find sufficient evidence that links cannabis directly to cancer. Large-scale, placebo controlled clinical trials are needed for scientists to be able to recommend cannabis for cancer treatment.
What we do know is that cannabis can be an effective remedy for side effects related to cancer and chemotherapy. These include pain, nausea, vomiting, insomnia, anxiety, and loss of appetite.
Cancer research shows promise
Animal studies in laboratory conditions have shown that cannabinoids can kill cancer cells without harming the healthy cells nearby. This gives scientists hope in the potential efficacy of CBD. While clinical trials on human subjects have been few and very slow – given the status of cannabis as a controlled substance in the United States – preclinical data already supports anecdotal reports from actual cancer patients. [R] [R] [R] [R]
Significant research has demonstrated that cannabinoids may slow down or stop the growth of cancers — including brain, breast, leukemia, liver, melanoma, pheochromocytoma, and other types of cancers. In a 2009 study, cannabinoids have proven to promote apoptosis (programmed death of tumor cells) while stopping angiogenesis (blood supply to the tumor). [R]
One particular study early this year conducted in Madrid showed that in one-third of rats treated, the injection of synthetic THC eliminated malignant brain tumors while extending life in another third. [R]
Even the National Cancer Institute has acknowledged that cannabis can kill cancer cells in a laboratory setting. The US government's principal agency for cancer research has devoted an entire section of its website to how cannabinoids affect the human body.
Preclinical (laboratory or animal) studies on CBD
Studies have demonstrated how cannabis can kill cancer cells in the laboratory. [R]
- Anti-tumor activity
Studies in mice have shown that cannabinoids may block cell growth and cause cell death. Laboratory and animal studies have shown that cannabinoids may be able to kill cancer cells without damaging healthy cells.
Another mice study exhibited anti-inflammation effects of cannabinoids on the colon – which could reduce the risk of colon cancer and possibly help in treatment of the disease.
In a laboratory study of THC, it was able to damage or kill tumor cells in hepatocellular carcinoma or liver cancer. The anti-tumor effects of THC acted on molecules that may also be found in lung cancer cells and breast cancer cells.
Another laboratory study showed how CBD could cause cancer cell death in estrogen receptor positive and estrogen receptor negative breast cancer cells while having little effect on healthy cells. CBD also reduced the growth, number, and spread of tumors in mouse models of metastatic breast cancer.
Cannabinoids were also able to kill cancer cells in glioma tumor models without harming normal cells in the central nervous system. When administered together with chemotherapy, CBD and THC enhanced the effects of chemo in killing human glioma cells.
- Stimulate appetite
Many animal studies have shown that THC, CBD and other cannabinoids can stimulate appetite and increase food intake in cancer models.
- Pain relief
Research has shown how receptors in the brain, spinal cord, and nerve endings respond to cannabinoids for pain relief. Animal studies demonstrated that cannabinoids may prevent nerve pain, numbness, tingling, swelling, and muscle weakness after chemotherapy.
- Control nausea and vomiting
Cannabinoid receptors found in human brain cells may have a role in controlling nausea and vomiting caused by chemotherapy. Animal studies have shown that THC and other cannabinoids are able to prevent vomiting post-chemo.
- Reduce anxiety and improve sleep
Several animal models have revealed the anti-anxiety effects of CBD. This might help cannabinoid receptors control mood and anxiety.
Human clinical trials of CBD on cancer patients
The therapeutic potential of CBD and other cannabinoids is now being studied in clinical trials to explore how they can help manage the side effects of cancer and chemotherapy. [R]
- Anti-tumor activity
One study in 2011 administered an oral spray of CBD and THC combined with temozolomide to treat recurrent glioblastoma multiforme. [R]
Another study analyzed CBD as treatment for acute graft-versus-host disease in patients who have undergone allogeneic hematopoietic stem cell transplantation.
- Control nausea and vomiting
Dronabinol (Marinol®) and Nabilone (Cesamet®) have been approved by the FDA for the treatment of chemotherapy-related nausea and vomiting in patients who have not responded to standard therapy. Many clinical trials have shown that both drugs work as well as or even better than other FDA-approved drugs for nausea and vomiting.
A small randomized, placebo-controlled, double-blinded clinical trial in Spain showed how oral spray Nabiximols (Sativex®) was able to relieve chemotherapy-related nausea and vomiting.
There have been 10 small trials on inhaling cannabis for the treatment of chemotherapy-related nausea and vomiting though there is not enough information to interpret these findings.
- Stimulate appetite
A clinical trial compared Dronabinol and standard drug Megestrol in patients with advanced cancer who had reported loss of appetite. Results showed that the THC in Dronabinol was not as effective in increasing appetite or weight gain compared to standard therapy. However, a clinical trial of patients with HIV /AIDS found that THC had increased appetite and increased weight compared with patients who took a placebo.
- Pain relief
In a small study of 21 patients suffering from chronic pain, vaporized cannabis combined with morphine provided better pain relief than morphine alone. On the other hand, combining vaporized cannabis with oxycodone did not produce significant pain relief. These findings require further studies.
Two small clinical trials of oral THC showed how it could possibly relieve cancer pain. In the first study, patients experienced pain relief as well as reduced nausea and vomiting and better appetite. The second study showed that THC could be administered in the same doses as codeine for pain relief.
An observational study of Nabilone also demonstrated relief from cancer pain along with reduced nausea, anxiety, and distress.
Another human trial showed that cannabis extract sprayed under the tongue can be effective in relieving cancer pain compared to opioids alone. Patients who received low doses of the cannabinoid spray showed remarkable pain control and experienced better sleep compared to patients who received a placebo. For some patients with advanced cancer, pain control continued even without increasing dosage of the cannabinoid spray.
- Reduce anxiety and improve sleep
A small case series found that patients who inhaled cannabinoids experienced better mood and reduced anxiety.
Studies on CBD and specific cancers
Scientists have discovered that CBD extracted from hemp might exhibit anti-tumor effects.
Cannabidiol or CBD can stop cell growth and induce apoptosis (cell death) in cervical cancer cells. Cannabinoids also increase lysis (cell decline) in lung cancer cells by lymphokine-activated killer cells via upregulation of ICAM-1. [R] [R]
Research from Complutense University in Spain revealed how cannabinoids can increase the absorption rate of chemotherapy medicine in cancer cells while simultaneously protecting healthy cells. [R]
In 2010, scientists investigated how the administration of CBD could activate TRPV2 and induce apoptosis in human T24 bladder cancer cells. [R]
Another study in 2010 showed how the addition of CBD to THC may improve the overall effectiveness of THC in the treatment of glioblastoma in cancer patients. [R]
The addition of CBD led to a dramatic drop of mitochondrial oxidative metabolism and viability in glioma cells. CBD significantly inhibited the growth of U87 human glioma cells. CBD was able to exhibit significant anti-tumor activity both in vitro and in vivo, which suggests a possible application of CBD as an antineoplastic agent. [R]
A systematic review of 35 published studies involving the anti-tumor effects of cannabinoids revealed the following activities: antiproliferative (cell cycle arrest), decreased viability and cell death by toxicity, apoptosis, necrosis, autophagy, as well as antiangiogenic and antimigratory effects. Evidence included a reduction in tumor size, antiangiogenic, and antimetastatic effects. The studies described the canabinnoids to have targeted distinct tumor models so that normal cells are not affected. This safety factor in anti-tumor effects has been demonstrated in vitro and in vivo. These findings indicate that cannabinoids may potentially treat gliomas. [R]
A 2005 study evaluated the ability of CBD to impair the migration of U87 glioma cells.
Cannabidiol was able to inhibit human glioma cell migration through a cannabinoid receptor-independent mechanism. The results further reinforce the evidence of CBD limiting tumor invasion. [R]
A 2013 study demonstrated that CBD significantly downregulates Id-1 gene expression and associated glioma cell invasiveness and self-renewal. Id-1 is a key transcriptional regulator of glioblastoma aggressiveness. [R]
The aggressive behavior of glioblastoma multiforme (GBM) is due to high invasiveness, proliferation rate, and resistance to standard chemotherapy. Temozolomide (TMZ), carmustine (BCNU) and doxorubicin (DOXO) displayed limited efficacy in the treatment of GBM. Activation of the transient receptor potential vanilloid type 2 (TRPV2) has been found to inhibit GBM cell proliferation and overcome BCNU resistance of GBM cells. Evaluating the role of CBD in TRPV2 activation, researchers found that CBD increases TRPV2 activity which sensitizes glioblastoma cells to cytotoxic chemotherapeutic agents. [R]
Another 2013 study found that CBD inhibited U87-MG and T98G cell proliferation and invasiveness in vitro. It also caused a decrease in the expression of proteins specifically involved in growth, invasion and angiogenesis. [R]
Local administration of THC- and CBD-loaded microparticles to mice bearing glioma xenografts reduced tumor growth. Treatment with cannabinoid-loaded microparticles also enhanced apoptosis and decreased cell proliferation and angiogenesis in these tumors. [R]
Scientists found that treatment regimens combining CBD and DNA-damaging agents (DNA-damaging agents (temozolomide, carmustine, cisplatin) produced synergistic antiproliferating and cell-killing responses in human GBM cell lines. [R]
A placebo-controlled study with 21 patients showed how THC and CBD extracts improved the survival of patients with recurrent glioblastoma, a particularly aggressive brain tumor, when given together with standard chemotherapy. The group with 12 random patients took Sativex together with temozolomide while the group with 9 patients took a placebo with temozolomide. Results showed that 83% of patients with documented recurrent glioblastoma treated with THC and CBD had survived the first year compared with 53% of patients in the placebo group. [R]
In a 2011 study conducted at the Beth Israel Deaconess Medical Center in Boston, CBD induced programmed cell death that inhibited the growth of breast cancer cells. [R]
A 2006 study investigated the anti-tumor activities of non-THC cannabinoids such as cannabidiol, cannabigerol, cannabichromene, cannabidiol acid and THC acid. Of the five compounds tested in a panel of tumor cell lines, cannabidiol was the most potent inhibitor of cancer cell growth with significantly lower potency in healthy cells. CBD inhibited the growth of xenograft tumors in a mice model of human MDA-MB-231 breast carcinoma. CBD also demonstrated a capability of inducing apoptosis. [R]
CBD slows down the proliferation and invasion of human breast cancer cells by differential modulation of the extracellular signal-regulated kinase (ERK) and reactive oxygen species (ROS) pathways. In two models of metastasis, CBD significantly reduced the size of primary tumor mass as well as the number of lung metastatic foci. With data demonstrating the efficacy of CBD in pre-clinical models of breast cancer, the results of the study could lead to the development of novel CBD therapies for the treatment of breast cancer metastasis. [R]
CBD could down-regulate Id-1 expression in aggressive human breast cancer cells. CBD represents the first non-toxic exogenous agent that can significantly decrease Id-1 expression in metastatic breast cancer cells leading to the down-regulation of tumor aggressiveness. [R]
Results of a 2012 investigation revealed that cannabidiolic acid (CBDA) inhibits migration of the highly invasive MDA-MB-231 human breast cancer cells through a mechanism involving inhibition of cAMP-dependent protein kinase A and activation of the small GTPase, RhoA. Data suggests that CBDA offers potential therapeutic modality in the abrogation of breast cancer cell migration. [R]
Similar findings came out in 2017 where CBDA mediated the down-regulation of c-fos in highly aggressive breast cancer MDA-MB-231 cells. [R]
Researchers from Italy published a study in 2012 showing that CBD can stop the development, growth, and spread of malignant tumors leading to colon cancer in rats. [R]
Scientists looked into the link between the anti-cancer activity of cannabinoids and induction of phosphatases. They concluded that cannabinoids induced apoptosis in colon and prostate cancer cell lines. [R]
Endocannabinoids are able to inhibit cell growth, invasion and metastasis of thyroid, breast and prostate tumors. [R]
Current treatments for Kaposi sarcoma can inhibit tumor growth but are unable to eliminate the Kaposi sarcoma herpes virus (KSHV) from the host. CBD is able to reduce proliferation and induce apoptosis in those infected by the virus. [R]
Results of a 2017 study indicate that CBD causes a reduction in leukemia cell size, which persists post-treatment. [R]
Data from a 2012 study showed how CBD could inhibit lung cancer cell invasion and metastasis by increasing tissue inhibitor of matrix metalloproteinases-1 (TIMP-1). [R]
COX-2 and PPAR-γ promoted CBD-induced apoptosis of human lung cancer cells. In primary cells from a patient with lung cancer, CBD elicited decreased viability associated with apoptosis. [R]
CBD caused a profound inhibition of A549 cell invasion, together with a decreased expression and secretion of plasminogen activator inhibitor-1 (PAI-1). In vivo, CBD had a significant downregulation of PAI-1 protein in A549 xenografts. Key data were confirmed in H460 and H358 human lung cancer cell lines. [R]
A study published in the British Journal of Pharmacology presented comprehensive evidence on how cannabinoids, especially CBD, act as potent inhibitors of prostate carcinoma viability in vitro. [R]
A team of Canadian scientists investigated the anti-tumor and anti-inflammatory activities of CBD in human prostate cancer cell lines LNCaP, DU145, PC3. Results indicate that CBD is a potent inhibitor of cancer cell growth, with significantly lower potency in healthy cells. An extract containing high levels of CBD downregulated CB1, CB2, VEGF, PSA, cytokines/chemokine IL-6/IL-8. Overall findings reveal that CBD may effectively inhibit spheroid formation in cancer stem cells. [R]
Research findings demonstrate that anandamide induces cytotoxicity in A375 human melanoma cells. [R]
Breakthrough in CBD for pancreatic cancer
Close to 9,800 people are diagnosed with pancreatic cancer every year in the United Kingdom. Pancreatic cancer is particularly aggressive and has very low survival rates.
Cancer in the pancreas is one of the deadliest cancers in the world. According to the American Cancer Society, the one-year relative survival rate is 20% for all stages of pancreatic cancer combined. It is the 12th most common cancer globally, with the highest incidence occurring in developed countries. [R]
Pancreatic cancer is often diagnosed in people over 75 years old. Only five percent of all patients survive for five years after the initial diagnosis. [R]
This year a breakthrough in cannabidiol research may have finally found a way to improve the average survival rate for pancreatic cancer patients.
In a study conducted by British scientists, mice with pancreatic cancer that were treated with CBD and chemotherapy survived nearly three times longer than those treated with chemotherapy alone. [R] [R]
"We found that mice with pancreatic cancer survived nearly three times longer if a constituent of medicinal cannabis was added to their chemotherapy treatment," said lead researcher Marco Falasco of Queen Mary University of London. "Cannabidiol is already approved for use in clinics, which means we can quickly go on to test this in human clinical trials. If we can reproduce these effects in humans, CBD could be in use in cancer clinics almost immediately, compared to having to wait for authorities to approve a new drug." [R]
cannabidiol (CBD) has already shown efficacy in alleviating the side effects of chemotherapy such as nausea and vomiting. The results from this study provide more justification for testing CBD in humans to explore the possible anti-cancer properties of cannabidiol. [R] [R]
While human trials on CBD as a possible cancer treatment option may move faster in the UK, legalization continues to hamper scientists in the US. Cannabis is still considered a Schedule 1 substance under federal law but that could change with the FDA approving the first CBD-based drug for treating severe forms of epilepsy last June.
Studies have linked CBD to promising results across many medical fields, including easing migraine pain, improving stroke recovery, and reducing seizure intensity. These findings underscore the importance of continued research on the effects of CBD on humans. [R] [R] [R]
"There is a large body of scientific data which indicates that cannabinoids specifically inhibit cancer cell growth and promote cancer cell death," said Dr. David Meiri -- lead researcher on an Israeli project studying 50 varieties of cannabis and its effects on 200 different cancer cells.
Dr. Meiri and his team have successfully killed brain and breast cancer cells through exposure to cannabis. In future studies they hope to find more varieties of cancer cells that would respond similarly.
This is not to say that people with cancer should forego traditional treatment options. Dr. Meiri warns that not all cancer cells respond to cannabinoids the same way. Placebo-controlled clinical trials are needed to fully understand how CBD can affect each type of cancer.
The future of CBD and cancer
Current scientific research certainly looks promising, but data has been limited to preclinical studies. They offer hope but CBD therapies must be carried out in actual human trials to confidently claim that cannabis has anti-cancer properties.
In order for cannabis to find its way into standard clinical cancer treatment, comprehensive and large-scale pharmacological studies need to be done. Lifting the federal ban on medical cannabis can surely help.
Recognizing the need for safer and more effective therapies in battling the debilitating side effects of cancer, the American Cancer Society supports the need for more scientific research on cannabinoids for cancer patients.
Even the federally-funded National Cancer Institute has acknowledged preclinical studies that show how cannabis could kill cancer cells.
Medical decisions about cancer symptom management should be between patient and doctor. Do not replace your traditional cancer treatment with CBD without talking to your doctor. Cancer treatment must balance benefit and harm, according to patient preference and values, and complying with applicable laws and regulations.