Cannabinoids are well known to possess palliative effects in oncology, including relief of chemotherapy-related vomiting and nausea, pain relief, appetite stimulation, mood elevation, and sleep in cancer patients (see our other articles on pain, anxiety, and sleep).
Research has been accumulating over the last several decades that cannabinoids are known to produce powerful results beyond palliative care, entering the “domain of disease modulation.”  More quality research is needed, but the direct anti-cancer results currently show an inhibition in the growth of new cancer cells, tumor-shrinking properties, and the prevention of metastases. Scientists have published multiple papers proving that cannabinoids can cause several different cancer types to regress.
In 2013, scientists reviewed the best available literature on the subject and wrote that,
“Cannabinoids possess anti-proliferative and pro-apoptotic effects and they are known to interfere with tumor neovascularization, cancer cell migration, adhesion, invasion and metastasization. However the clinical use of ∆9 THC and additional cannabinoid agonists is often limited by their unwanted psychoactive side effects, and for this reason interest in non-psychoactive cannabinoid compounds…such as cannabidiol (CBD), has substantially increased in recent years.”
Several studies limited to synthetic versions of CBD and THC showed anti-cancer effects. A Japanese study using THC determined that it had anti-inflammatory effects and reduced the development of tumors in mice. 
Another study had researchers discover that cannabidiol (CBD) may prevent cancer caused by smoking tobacco, linked to cytochrome p450, family 1, member A1 (CYP1A1). CYP1A1 is a protein found in humans. The protein is harmless at low levels, but has been shown to be cancerous in high amounts. Cannabidiol was found to bind to the protein, keeping it from increasing. It was able to control CYP1A1, keeping it at a normal healthy level, exerting a potent preventative effect on cancer caused by smoking. 
Utilizing cannabis as a therapeutic tool to reduce cancer activity and tumor size does require high doses of cannabis medicine. Tetrahydrocannabinol is highly effective in shrinking the tumor size,  and CBD is very effective in stopping the proliferation of new cancer cells.  While both CBD and THC are effective anti-cancer agents, the combination of CBD and THC together has shown even greater efficacy for healing. There is a very real and well documented synergistic relationship between CBD and THC; as we’ve shared before in our other articles on full spectrum hemp extracts, the whole is greater than the sum of the parts. There is research from Dr Ethan Russo and other cannabis scientists, proving that a full spectrum of cannabinoids and terpenes derived from the whole hemp plant is the most effective approach (see our other article covering the Entourage Effect).
In a study, that is considered to be one of the most in-depth thus far on cancer patients and cannabinoids, involving well over fifty different strains of cannabis and over two hundred cancer cell lines, the lead researcher, Dr. David Meiri stated, “in addition to active cannabinoids, cannabis plants also contain a multitude of other therapeutic agents” and that, “terpenoids and flavonoids are usually present in small quantities, but can have beneficial therapeutic effects, especially as synergistic compounds to cannabinoids.”  Strains of cannabis that are high in limonene, myrcene, and linalool are recommended. 
A 2013 study, showed that a full spectrum of cannabinoids was significantly more effective in the treatment of leukemia cells, compared to dosing each individual compound on its own.  Dr. Meiri and his team are conducting a number of studies documenting the results of cannabinoids and other phytochemicals on tumor development:
“The effects were further investigated in vitro, in various cancer cell lines, and revealed pro-apoptotic (promoting cancer cell death) and antiproliferative response to cannabinoids, as well as inhibition of invasion and migration. However, the medical use of cannabis remains rather limited due to the large number of active compounds that, together with variability among different cannabis strains and cultivation methods, impairs our ability to predict the specific clinical effect and determine the recommended dose.” 
Additional research is continuing to be undertaken on the other active compounds found in cannabis, such as terpenes, and high-quality studies on human participants are starting to be published, some cancer sufferers don’t have the time to wait. Hundreds of stories exist of people whose cancer was cleared after cannabinoid therapy. Currently, many of the anti-cancer results of cannabinoids are shown through either test tube or animal models, with only a few studies in humans published.
The information contained in this article is for informational purposely only and does not constitute medical advice. Prior to making changes to your lifestyle or treatment plan, consult with a licenced medical professional. When utilizing cannabis, it is recommended to work with a Doctor experienced in medicinal cannabis or CBD so that delivery methods and dose may be customized to the individual. While highly educated and aware people may also become their own highly informed health consultants.
As with all cannabis or CBD dosing, start with a micro dose to test for sensitivity, then slowly go up as needed within the dosing range by body weight until symptoms subside. Dosages for advanced cancers are generally in the macro dose range, with a suggested range of 200mg to 2,000g of total cannabinoids per day. The most common suggested ratio of CBD to THC is 1:1. However, at the macro dose level, most people often have difficulty tolerating medication with the higher amount of THC. In the initial stages of taking macro doses, most are not able to tolerate more than 20-30mg of tetrahydrocannabinol from an oral application. Over a four to six week time period, people are often found to have a higher tolerance level and become acclimated to high doses. Be sure to slowly titrate up dosages of THC carefully, and research ways to minimize the sides or impairment.
When high doses are required, many people will utilize a concentrated form of cannabis oil and take it orally, in capsule form, or by adding it to food (nut butters seem to work well for this purpose). The purest, most potent concentrates are created using a CO2-extraction process. For more immediate relief of symptoms such as pain, nausea, or loss of appetite, smoked or vaporized cannabis can be highly effective. This approach lasts one to three hours, whereas most ingested products take thirty to sixty minutes before taking effect and last six to eight hours. The most effective vaporizers utilize cartridges filled with the CO2 concentrate, and these are available in various ratios of THC to CBD.
The Cannabis Health Index, which is a scoring system based on the best available evidence for cannabis in the treatment of various conditions and illnesses, rates the following cancers out of five, with one being the lowest score (1-5). Keeping in mind, in many of these conditions, the research just isn’t there, which means the score rating is lower, than if there’s more research available to rank from.
A 2010 study found that CBD induced the death of human urothelial carcinoma cells with the medical team concluding that they had identified a potential therapeutic target for bladder cancer.  Another study from 2013, had scientists discover that cannabis use seemed to reduce the risk of bladder cancer in the evaluation of nearly 85,000 men in California.
A 2004 study found that CBD had the ability to produce significant anti-tumor activity in both vitro and in vivo, hence suggesting a probable application of cannabidiol as an antineoplastic agent.  Authors of a 2010 study wrote:
“The CB1 and CB2 receptor agonist ∆-9 tetrahydrocannabinol has been shown to be a broad-range inhibitor of cancer in culture and in vivo, and is currently being used in a clinical trial for the treatment of glioblastoma. It has been suggested that other plant-derived cannabinoids, which do not interact efficiently with CB1 and CB1 receptors, can modulate the actions of ∆-9 THC.” 
In multiple glioblastoma cell lines, CBD and THC worked synergistically together to prevent cancer cell development. The treatment of glioblastoma cells with both of these cannabis compounds led to significant changes in the cancer cell life cycle, and brought on a reduction in oxidative damage while destroying cancer cells. These exact changes to the cancer were not found with either compound individually, but only when administered together as a synergistic cancer fighting team. These results seem to suggest that combining CBD with THC may improve the overall effectiveness in the treatment of glioblastoma in cancer sufferers. 
In 2013, GW Pharmaceuticals started the first human trials to study the potential benefits of its 1:1 ratio product Sativex in the treatment of glioblastoma multiforme, a highly aggressive form of brain cancer that makes up half of all new brain cancer diagnoses in the US. The company announced that it had found positive top-line results from the exploration of Phase 2 placebo-controlled study early in 2017.  A 2014 review of the literature confirmed that, in a variety of experimental studies, cannabinoids produced anti-tumor activity in vitro and/or produced anti-tumor evidence in vivo in several models of tumor cells and tumors. The anti-tumor activity also included anti-proliferative results (preventing cancer cell growth), decreased viability, and cancer cell death via apoptosis, toxicity, necrosis, autophagy, as well as antiangiogenic and antimigratory effects. Anti-tumor evidence included a reduction in the size of tumors, antiangiogenic, and antimetastatic results. Also, the majority of the studies described that cannabinoids exercised selective antitumor action in several distinct tumor models. This means that normal healthy cells used as comparisons in the treatment, were not affected at all. The various cannabinoids tested in multiple models of tumors showed anti-tumor results both in vivo and vitro. These findings seem to show that cannabinoids are extremely promising compounds for the treatment of gliomas.  Cristina Sanchez, a cancer researcher at the University of Spain, stated in a 2015 interview that glioblastoma tumors are more responsive to a higher tetrahydrocannabinol content in the CBD:THC ratio.  See the video below for an interview on this topic with Dr Sanchez.
In a 2018 study, researchers insisted on the importance of cannabis use in glioblastoma brain tumors stating, “the effects of cannabinoids can be potentially enhanced by combination of different cannabinoids with each other or with chemotherapeutic agents.” They went on to share that, “despite aggressive therapeutic approaches consisting of maximum safe surgical resection and radio-chemotherapy, more than 95% of GBM patients die within 5 years after diagnosis.” Promisingly, they also mention that “recent phase II (human) clinical trials indicated positive results regarding the survival of GBM patients upon cannabinoid treatment.” 
In another 2018 study, scientists stated that, “cannabinoids elicit effects at different levels of cancer progression, including inhibition of proliferation (growth), neovascularization, invasion and chemoresistance, induction of apoptosis (cancer cell death) and autophagy as well as enhancement of tumour immune surveillance.” 
Depending on the country in which you reside and the corresponding state laws, you can purchase CBD oil via a prescription from your doctor, or over the counter. In New Zealand, you can legally purchase CBD oil with a prescription. In countries like the USA, some states allow the sale of CBD over the counter. Sativex, for example, is a prescription only medication, whereas some other full spectrum CBD products can be found on the shelves in various states. As always, before making changes to your treatment plan, consult with a licenced medical professional.
In a 2006 study, researchers acknowledged the anti-tumor effect of tetrahydrocannabinol and focused their efforts on the antitumor activities of other plant-based cannabinoids such as cannabidiol (CBD) for breast and other cancers. The results from a panel of tumor cell lines clearly indicated that, based on the five natural compounds tested, CBD was the most potent in preventing cancer cell development. 
Studies in 2010 focused on ErbB2-positive types of breast cancers that are usually resistant to treatment had scientists conclude that there is strong evidence for the use of cannabinoids to treat this type of cancer. 
In a 2015 study, which was focused on the anti-tumor role and mechanism of CBD against very aggressive breast cancer cell lines including triple-negative (TNBC). It showed for the first time that:
"CBD inhibits breast cancer growth and metastasis through novel mechanisms by inhibiting EGF/EGFR signaling and modulating the tumor microenvironment. These results also indicate that CBD can be used as a novel therapeutic option to inhibit growth and metastasis of highly aggressive breast cancer subtypes including TNBC, which currently have limited therapeutic options and are associated with poor prognosis and low survival rates." 
In a 2015 interview, Cristina Sanzhez stated that her research showed breast cancer was responsive to cannabis therapy, and it was even more responsive when the CBD:THC ratio was much higher in CBD. 
In a 2011 study, scientists discovered that cannabidiol could promote the death of prostate and colon cancer cells and that the activity was linked to enzymes that remove phosphates from proteins and modulate the activities of these enzymes. In the following year, an animal trial showed that colorectal carcinoma cell lines, “cannabidiol protected DNA from oxidative damage, increased endocannabinoid levels and reduced cell proliferation in a CB(1)-, TRPV1- and PPARγ-antagonists sensitive manner. It is concluded that cannabidiol exerts chemopreventive effect in vivo and reduces cell proliferation through multiple mechanisms.” 
In a 2008 study analyzing the available literature, researchers reported that, “recent evidence indicates that endocannabinoids influence the intracellular events controlling the proliferation of numerous types of endocrine and related cancer cells, thereby leading to both in vitro and in vivo anti-tumor results. In particular, they are able to inhibit cell growth, invasion and metastasis of thyroid, breast and prostate tumors.”  This is important to note, as the body's own endocannabinoid system (ECS) is a molecular system responsible for maintaining balance across all major bodily functions. Errors to the ECS, result in errors in cells, and errors in cells result in the growth of tumors, cancerous tissues and degenerative conditions. (For more information on the endocannabinoid system, read our full article The Endocannabinoid System Explained).
In a 2012 study, scientists discovered a potential biochemical mechanism for the results of CBD on tumors caused by Kaposi’s sarcoma-associated herpesvirus (KSHV). This is a very prevalent type of cancer among the elderly in the Mediterranean region, immune-compromised individuals such as organ transplant recipients, inhabitants of sub-Saharan Africa, and AIDS patients. The treatments currently available for Kaposi’s sarcoma can prevent tumor development but they aren’t effective in completely eradicating KSHV in the host. When the immune system of the host becomes weaker, KSHV starts to replicate again, and active tumors begin growing again. “New therapeutic approaches are needed,” the authors wrote, mentioning that CBD “exhibits promising anti-tumor effects without including psychoactive side effects.” 
A 2013 initiative was carried out by Dr. Wai Liu and colleagues involved the use of a number of cannabinoids, either in combination with each other or alone, to test their anti-cancer properties in relation to leukemia. Out of the six cannabinoids studied, every single one of them possessed anticancer properties just as effective as those seen from tetrahydrocannabinol. Even more impressive, they were more potent in their results on cancer cells when combined with each other.
The cannabinoids showed the ability to cause problems in the development of cancerous cells, halting their growth and preventing them from spreading. In some tests, the researchers were able to completely destroy cancer cells using unique dosage patterns of cannabinoids.
When cannabinoids are combined with existing treatment options, we would find some very potent strategies for fighting cancer. Importantly, these cannabis compounds are cheap to produce and by implementing them in treatment plans, could reduce the cost of anti-cancer drugs in the future. 
The study actually tested two forms of cannabidiol (CBD), two forms of cannabigevarin (CBGV), and two forms of cannabigerol (CBG), which account for two of the most common cannabinoids found in cannabis besides from tetrahydrocannabinol.
In a 2010 study, researchers first discovered evidence of cannabidiol’s anti-invasive anticancer action on human lung cancer cells. Two years later, german scientists were, quite incredibly, able to show for the first time, exactly how CBD kills cancer cells in human lung cancers. 
In a 2013 study review, researchers showed comprehensive evidence of plant-based cannabinoids ability to prevent the viability of prostate carcinoma in vitro. The study also showed that the cannabinoid extract was active when used with drugs commonly used to treat prostate cancer (Casodex or Taxotere), or alone, on its own. They also examined the potential mechanism behind these antineoplastic results.  The next year, researchers also studying the benefits of CBD on prostate cancer found that their results clearly indicated that CBD possesses potent preventative effects on cancer cell development, with much less potency in non-cancer cells. They went on to state that treatment with CBD, “may effectively inhibit spheroid formation in cancer stem cells. This activity may contribute to its anticancer and chemosensitizing effect against prostate cancer.” 
The most common form of cancer is by far and large, skin cancer, with over 3.5 million new people diagnosed each year in the US, and over 4000 people in New Zealand annually (with a population size of almost 5 million), which equates to 13 people each day. In a 2013 study, researchers found that the endocannabinoid produced by the endocannabinoid system called anandamide, possessed anticancer properties in human cutaneous melanoma cells.  Cannabidiol may prove effective, as it has the ability to help the body make more anandamide, which has a similar chemical makeup to that of tetrahydrocannabinol. (Full more information on anandamide and how to raise levels in the body by combining hemp with maca, see our article on Hemp and Maca).
The National Cancer Institute, is an organization run by the US Department of Health and Human Services, acknowledges cannabis as a powerful treatment option for effective relief of a variety of symptoms associated with chemotherapy and cancer treatments, including nausea and vomiting, pain, loss of appetite, and anxiety.  For a long time, cannabis has been shown to effectively reduce the vomiting and nausea that often occurs after chemotherapy treatments. Studies have demonstrated that CBD is effective at treating various intractable symptoms of nausea, along with preventing anticipatory nausea in chemotherapy patients.  
In one study, cancer patients suffering with neuropathic pain who had previously and unsuccessfully tried to manage their discomfort with opioids saw, after two weeks, a large reduction in pain levels after being given cannabis oil containing both CBD and THC.  (For more information on pain relief, read our article on How Hemp Works for Pain).
Cannabis has also been shown to aid in preventing weight loss and loss of appetite in chemotherapy patients. Tetrahydrocannabinol has been found to strongly stimulate appetite in people who have cachexia related to cancer. Also, patients undergoing chemotherapy and given THC have a large appetite and report that food just “tastes better.”  Typically, a low dose of THC, roughly 2.5 mg, can assist with weak appetite with very few sides.
Research has also shown that cannabis may assist with reducing swelling in the hands and feet that can come with chemotherapy. Both CBD and THC have shown to possess antiinflammatory properties. 
In a survey of 131 cancer patients participating in cannabis treatments for six to eight weeks, all measured symptoms were reported with significant improvements, including vomiting, nausea, fatigue, weight loss, mood disorders, anorexia, sexual function, constipation, sleep disorders, pain, and itching.  Those given tetrahydrocannabinol were found to experience a higher quality of relaxation and sleep.