Marijuana and Cancer
Marijuana is the name given to the dried buds and leaves of varieties of the Cannabis sativa plant, which can grow wild in warm and tropical climates throughout the world and be cultivated commercially. It goes by many names, including pot, grass, cannabis, weed, hemp, hash, marihuana, ganja, and dozens of others.
Marijuana has been used in herbal remedies for centuries. Scientists have identified many biologically active components in marijuana. These are called cannabinoids. The two best studied components are the chemicals delta-9-tetrahydrocannabinol (often referred to as THC), and cannabidiol (CBD). Other cannabinoids are being studied.
At this time, the US Drug Enforcement Administration (DEA) lists marijuana and its cannabinoids as Schedule I controlled substances. This means that they cannot legally be prescribed, possessed, or sold under federal law. Whole or crude marijuana (including marijuana oil or hemp oil) is not approved by the US Food and Drug Administration (FDA) for any medical use. But the use of marijuana to treat some medical conditions is legal under state laws in many states.
Dronabinol, a pharmaceutical form of THC, and a man-made cannabinoid drug called nabilone are approved by the FDA to treat some conditions.
Different compounds in marijuana have different actions in the human body. For example, delta-9-tetrahydrocannabinol (THC) seems to cause the “high” reported by marijuana users, and also can help relieve pain and nausea, reduce inflammation, and can act as an antioxidant. Cannabidiol (CBD) can help treat seizures, can reduce anxiety and paranoia, and can counteract the “high” caused by THC.
Different cultivars (strains or types) and even different crops of marijuana plants can have varying amounts of these and other active compounds. This means that marijuana can have different effects based on the strain used.
The effects of marijuana also vary depending on how marijuana compounds enter the body. The most common ways to use marijuana are in food (edible marijuana) and by smoking or vaping it (inhaled marijuana):
- Edible marijuana: When taken by mouth, such as when it’s used in cooking oils, drinks (beer, tea, vodka, soda), baked goods (biscuits, brownies, cookies), and candy, the THC is absorbed poorly and can take hours to be absorbed. Once it’s absorbed, it’s processed by the liver, which produces a second psychoactive compound (a substance that acts on the brain and changes mood or consciousness) that affects the brain differently than THC. It’s important to know that the amount of THC in foods that have had marijuana added to them is often unknown and getting to much THC might cause symptoms of overdose.
- Inhaled marijuana: When marijuana is smoked or vaporized, THC enters the bloodstream and goes to the brain quickly. The second psychoactive compound is produced in small amounts, and so has less effect. The effects of inhaled marijuana fade faster than marijuana taken by mouth.
How can marijuana affect symptoms of cancer?
A number of small studies of smoked marijuana found that it can be helpful in treating nausea and vomiting from cancer chemotherapy.
A few studies have found that inhaled (smoked or vaporized) marijuana can be helpful treatment of neuropathic pain (pain caused by damaged nerves).
Smoked marijuana has also helped improve food intake in HIV patients in studies.
There are no studies in people of the effects of marijuana oil or hemp oil.
Studies have long shown that people who took marijuana extracts in clinical trials tended to need less pain medicine.
More recently, scientists reported that THC and other cannabinoids such as CBD slow growth and/or cause death in certain types of cancer cells growing in lab dishes. Some animal studies also suggest certain cannabinoids may slow growth and reduce spread of some forms of cancer.
There have been some early clinical trials of cannabinoids in treating cancer in humans and more studies are planned. While the studies so far have shown that cannabinoids can be safe in treating cancer, they do not show that they help control or cure the disease.
Relying on marijuana alone as treatment while avoiding or delaying conventional medical care for cancer may have serious health consequences.
Possible harms of marijuana
Marijuana can also pose some harms to users. While the most common effect of marijuana is a feeling of euphoria (“high”), it also can lower the user’s control over movement, cause disorientation, and sometimes cause unpleasant thoughts or feelings of anxiety and paranoia.
Smoked marijuana delivers THC and other cannabinoids to the body, but it also delivers harmful substances to users and those close by, including many of the same substances found in tobacco smoke.
Because marijuana plants come in different strains with different levels of active compounds, it can make each user’s experience very hard to predict. The effects can also differ based on how deeply and for how long the user inhales. Likewise, the effects of ingesting marijuana orally can vary between people. Also, some chronic users can develop an unhealthy dependence on marijuana.
There are 2 chemically pure drugs based on marijuana compounds that have been approved in the US for medical use.
- Dronabinol (Marinol®) is a gelatin capsule containing delta-9-tetrahydrocannabinol (THC) that’s approved by the US Food and Drug Administration (FDA) to treat nausea and vomiting caused by cancer chemotherapy as well as weight loss and poor appetite in patients with AIDS.
- Nabilone (Cesamet®) is a synthetic cannabinoid that acts much like THC. It can be taken by mouth to treat nausea and vomiting caused by cancer chemotherapy when other drugs have not worked.
Nabiximols is a cannabinoid drug still under study in the US. It’s a mouth spray made up of a whole-plant extract with THC and cannabidiol (CBD) in an almost one to one mix. It’s available in Canada and parts of Europe to treat pain linked to cancer, as well as muscle spasms and pain from multiple sclerosis (MS). It’s not approved in the US at this time, but it’s being tested in clinical trials to see if it can help a number of conditions.
How can cannabinoid drugs affect symptoms of cancer?
Based on a number of studies, dronabinol can be helpful for reducing nausea and vomiting linked to chemotherapy.
Dronabinol has also been found to help improve food intake and prevent weight loss in patients with HIV. In studies of cancer patients, though, it wasn’t better than placebo or another drug (megestrol acetate).
Nabiximols has shown promise for helping people with cancer pain that’s unrelieved by strong pain medicines, but it hasn’t been found to be helpful in every study done. Research is still being done on this drug.
Side effects of cannabinoid drugs
Like many other drugs, the prescription cannabinoids, dronabinol and nabilone, can cause side effects and complications.
Some people have trouble with increased heart rate, decreased blood pressure (especially when standing up), dizziness or lightheadedness, and fainting. These drugs can cause drowsiness as well as mood changes or a feeling of being “high” that some people find uncomfortable. They can also worsen depression, mania, or other mental illness. Some patients taking nabilone in studies reported hallucinations. The drugs may increase some effects of sedatives, sleeping pills, or alcohol, such as sleepiness and poor coordination. Patients have also reported problems with dry mouth and trouble with recent memory.
Older patients may have more problems with side effects and are usually started on lower doses.
People who have had emotional illnesses, paranoia, or hallucinations may find their symptoms are worse when taking cannabinoid drugs.
Talk to your doctor about what you should expect when taking one of these drugs. It’s a good idea to have someone with you when you first start taking one of these drugs and after any dose changes.
What does the American Cancer Society say about the use of marijuana in people with cancer?
The American Cancer Society supports the need for more scientific research on cannabinoids for cancer patients, and recognizes the need for better and more effective therapies that can overcome the often debilitating side effects of cancer and its treatment. The Society also believes that the classification of marijuana as a Schedule I controlled substance by the US Drug Enforcement Administration imposes numerous conditions on researchers and deters scientific study of cannabinoids. Federal officials should examine options consistent with federal law for enabling more scientific study on marijuana.
Medical decisions about pain and symptom management should be made between the patient and his or her doctor, balancing evidence of benefit and harm to the patient, the patient’s preferences and values, and any laws and regulations that may apply.
The American Cancer Society Cancer Action Network (ACS CAN), the Society’s advocacy affiliate, has not taken a position on legalization of marijuana for medical purposes because of the need for more scientific research on marijuana’s potential benefits and harms. However, ACS CAN opposes the smoking or vaping of marijuana and other cannabinoids in public places because the carcinogens in marijuana smoke pose numerous health hazards to the patient and others in the patient’s presence.
Learn how marijuana and drugs derived from the marijuana plant can affect cancer-related symptoms.
Cannabis is the dried preparation, or resinous extract, of the flowers or leaves of the cannabis plant, a member of the hemp family. It is an illegal drug in many countries, including the UK.
The parts of cannabis that are considered important for medical reasons are called cannabinoids. This is the name for the complex chemicals found in cannabis that are responsible for the effect cannabis has on the body. Two cannabinoids are of particular interest:
- THC – delta-9 tetrahydrocannabinol (responsible for the psycho-active and addictive effects of cannabis)
- CBD – cannabidiol
It’s important to make clear the difference between cannabis, cannabis oil and CBD oil.
Cannabis and cannabis oil
Cannabis and cannabis oil are classified as a class B drug in the UK, because they contain the component THC. It is illegal to possess or supply them. However, from 01 November 2018, cannabis-based products for medicinal use will be available in the UK in some circumstances only.
Only specialist doctors who are listed in the General Medical Council’s (GMC) specialist register will be able to prescribe cannabis-based products. They will only be prescribed when the specialist considers that the patient will benefit and when the patient has an unmet special clinical need that cannot be met by licensed products.
- Medicinal cannabis, therefore, will be prescribed on a case-by-case basis
- Patients will NOT be able to get cannabis-based products from their GP
- If you feel you might benefit from these products, speak to your consultant or healthcare team
- Administration by smoking remains prohibited.
(For more information, see our blog on cannabis-based medicinal products.)
CBD oil is different from cannabis oil, because it does not contain THC.
It is currently legal in the UK – as long as it has been produced from an EU approved strain of hemp and as long as it is marketed as a food supplement without any medicinal claims. You can buy it in many high street health food shops.
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What is the evidence for cannabis-based products in the treatment of brain tumours?
Treating the side-effects of a brain tumour
There’s now conclusive evidence for the use of cannabis and its products, such as cannabis oil and CBD oil, for other therapeutic purposes, i.e. pain relief and treating chemotherapy-induced nausea and vomiting.
As such, the cannabis-based drug, Nabilone, has a medical licence and can be legally prescribed for chemotherapy-induced nausea and vomiting.
Treating the brain tumour itself
Currently, the evidence that cannabis-based products can treat brain tumours themselves is limited.
There have been some promising pre-clinical trials in mice, in which THC, CBD and radiotherapy used together appeared to slow tumour growth. More research involving clinical trials in people needs to be done.
There have also been some positive results using a drug called Sativex (a combination of THC and CBD) alongside the chemotherapy drug temozolomide (TMZ). It was found that in people with recurrent glioblastoma, those treated with Sativex had a higher chance of longer survival time, compared to those who didn’t have the drug.
However, it was a small trial, on only 21 patients, to test the safety and effectiveness of using Sativex. The next stage will be to look at whether Sativex works better than standard treatment or whether it produces fewer side-effects. Although a large amount of progress has been made, it could be up to another five years before this drug is licensed for use in brain tumour patients.
How can I get cannabis-based products?
Speak to your healthcare team.
Apart from the special circumstances described earlier above, and the prescribing of Nabilone for chemotherapy-induced nausea and vomiting, it might be possible for Sativex to be accessed via off-label prescribing.
Off-label prescribing is where your doctor can prescribe a drug licenced for another condition, if they feel it would benefit you and there is no other licensed treatment or all licensed treatments have failed. Sativex is licensed for the treatment of spasticity (tightening of the muscles) in multiple sclerosis.
However, many doctors may be reluctant to prescribe off-label as the responsibility for the prescribing and any adverse effects, lies with them. Also the professional codes, ethics and prescribing policies of their hospital trust may prevent it. You can always speak to your doctor about this.
Some people affected by a brain tumour may decide to self-medicate with cannabis.
We would always recommend that any supplements, alternative or complementary treatments that you/your loved one wishes to use are discussed with your/their medical team. This is because it may, for example, interact with other medications, such as anti-epileptic medicines, steroids or chemotherapy.
It is important to be aware that you cannot be sure of the concentrations and ratios of THC and CBD in grown or street cannabis.
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There’s conclusive evidence for the use of cannabis and its products, such as cannabis oil and CBD oil, for other therapeutic purposes.