If you have prostate cancer, you may wonder whether marijuana can help treat it or relieve symptoms. Here’s what research shows. In our hospital we notice the popular use of cannabis oil in prostate cancer (PCa) patients, they even replace standard treatment with the use of cannabis oil.
Can Medical Marijuana or CBD Help With Prostate Cancer?
Medical marijuana is often used to treat conditions such as chronic pain, Parkinson’s disease, multiple sclerosis, epilepsy, and Crohn’s disease. Though it’s been studied, there’s not a lot known about whether it can help treat cancer, particularly prostate cancer. Here’s what science does show.
THC vs. CBD: What’s the Difference?
The major components of marijuana are THC (tetrahydrocannabinol) and CBD (cannabidiol). These are known as cannabinoids. THC is what gets you high. CBD does not get you high. Rather, it gives you a mellow, comfortable feeling.
Can Medical Marijuana Treat Prostate Cancer?
There are very well established treatments for prostate cancer that include testosterone blockers, radiation, and surgery as well as other medications. Cannabinoids have been shown to have some activity against prostate cancer in the lab and in mice. But it is not recommended for prostate cancer treatment.
Like other chemicals, these cannabinoids can bind to a part of a cell known as a cell receptor and then influence the cell’s behavior. Cell receptors that bind to cannabinoids fall into two categories:
- CB1. These receptors are mostly found in the brain and responsible for the potentially pain-relieving properties of marijuana.
- CB2. These receptors are in the cells of the immune system and blood-forming organs, and may also be in other tissues. When scientists stimulate these receptors with cannabinoids, they’ve been able to kill cancer cells from a variety of human tumors, including brain cancer, lymphomas, and breast cancer.
Research suggests that these cannabinoids help regulate cell growth. They also seem to prevent the growth of cancer cells by making them less likely to survive, grow, spread, and stick to other cancer cells. This means that they may be able to treat many different kinds of cancer, including prostate cancer.
It’s thought that marijuana specifically targets tumor cells but doesn’t really target non-tumor cells. This means that it may be less toxic to the body than other forms of treatment, like chemotherapy.
Research also shows that prostate cancer cells have higher levels of both CB1 and CB2 receptors than normal cells. This means that these cancer cells might be more attracted to cannabinoids than normal cells. Laboratory studies have shown that when these cells are treated with cannabinoids, three things happen:
- The cells are more likely to die.
- Androgen receptor activity on the prostate cancer cell surface decreases. This is important because prostate cancer is fueled by androgens, which are male hormones.
- THC and CBD discourage the formation of tumor blood vessels, which prostate cancer cells need to feed and grow.
One Spanish study found that when cannabinoids were added to three different types of human prostate cancer cells, they slowed the growth of all of them. In fact, the cannabinoids that targeted CB2 were able to kill prostate cancer cells by triggering apoptosis, aka cell death by suicide.
The researchers then transplanted one type of human prostate cancer cell, an aggressive form of cancer known as PC-3, into mice. They divided the mice into three groups: one treated with salt water, one with a cannabinoid, and the third with the same cannabinoid plus a chemical that blocked its effects on CB2. The mice who received the cannabinoid alone experienced a significant reduction in tumor growth compared to the other two groups.
These studies have only looked at prostate cancer cells grown in laboratories or in mice. There are no studies looking at how cannabinoids work in humans, so we don’t know if they would work the same way in people. It’s also unclear exactly how cannabinoids prevent prostate cancer cells from getting bigger or dividing.
Can I Use Medical Marijuana to Relieve Symptoms From Prostate Cancer Treatment?
Research shows that medical marijuana may help with:
- Cancer-related pain. It can help with severe pain, especially if it’s used with opioids. The combination may decrease pain signals in the brain as well as inflammation.
- Neuropathy. This is a feeling of weakness, numbness, tingling, or burning in the hands or feet due to nerve damage. It’s a common side effect of chemotherapy. Animal studies show that cannabinoids can help relieve some of the symptoms, but human studies are mixed.
- Nausea and vomiting. Dronabinol and nabilone are synthetic cannabinoids the FDA approved for the treatment of chemotherapy-induced nausea and vomiting. There isn’t research on other forms of marijuana such as smoking, vaping, or CBD oil.
- Weight loss. Some research shows that THC may help ramp up appetite and slow down weight loss in people with advanced cancer.
Is It Safe to Use Medical Marijuana or CBD Oil With Prostate Cancer?
There are some risks. These include:
- Loss of control over movement, disorientation, and feelings of anxiety or paranoia. carries health risks since it contains many of the same substances found in tobacco smoke.
- Unpredictability. Marijuana plants come in different strains with different levels of active compounds. This makes it harder to predict how you’ll respond to it.
How Can You Get CBD and Medical Marijuana?
You may also have heard of CBD oil. It’s sold everywhere from your grocery store to vitamin shops. It doesn’t contain THC, the ingredient in marijuana that gets you high. CBD is usually sold as an oil, but you can also find it as an extract, a vaporized liquid, edibles like gummies, in foods, in drinks, and in beauty products. Remember, CBD is not regulated by the FDA, so it’s also hard to know how much CBD you’re getting. One study of 84 CBD products found that more than a quarter contained more CBD than was on the label, and some products even contained THC.
The only medical marijuana product approved by the FDA is a prescription oil called Epidiolex to treat epilepsy. There’s no research to suggest it can treat prostate cancer or relieve cancer treatment-related symptoms. It also may cause side effects like:
- Dry mouth
- Loss of appetite
It may also interact with other medications you take, like blood thinners. Talk to your doctor to make sure you don’t have any medical conditions that make using it unsafe.
If you’re considering using medical marijuana, check your state regulations. If it’s legal, you should be able to purchase it at a medical dispensary.
Harvard Health Publishing: “Pot for the Prostate,” “CBD Products Are Everywhere, but Do They Work?”
International Journal of Molecular Sciences: “Cannabinoids and Prostate Cancer: A Systematic Review of Animal Studies.”
British Journal of Pharmacology: “Non-THC Cannabinoids Inhibit Prostate Carcinoma Grown in Vitro and in Vivo: Pro-apoptotic Effects and Underlying Mechanisms.”
British Journal of Cancer: “Inhibition of Human Tumor Prostate PC-3 Cell Growth by Cannabinoids R(+)-Methanandamide and JWH-015: Involvement of CB2.”
Using cannabis in prostate cancer patients
In our hospital’s daily practice we notice the popular use of cannabis oil in prostate cancer (PCa) patients. As a nursing specialist for urology, I have even met patients who are so convinced of the curative benefits of cannabis oil in treating prostate cancer that they replace standard treatment with the use of cannabis oil.
These patients include those who have localised prostate cancer where active surveillance is followed, those with biochemical recurrence after treatment, and patients with metastatic PCa. I have always wondered whether cannabis oil could indeed be a cure for prostate cancer. Unfortunately, I do not see in practice the desired beneficial effect and the PSA values continue to rise. To find some answers, I did a search in scientific literature.
Cannabis, a very easy plant to grow, has been used for centuries for its medicinal properties. The oldest known document about cannabis use originates from the Chinese emperor Shen Nung in 2727 B.C. It suggested that cannabis has a neuron-protective effect. The Egyptians used cannabis to treat glaucoma and as an anti-inflammatory agent (inflammation of the eyes, fever). Cannabis was even used in obstetrics (mixed with honey) and the mixture was applied in the vagina to “cool” the uterus. In the Old Testament, there is also an account of God instructing Moses to make a holy anointing olive oil-based “Kaneh Bosm.”
Cannabis contains more than 400 chemical components 80 of which contain cannabinoid components and 200 non-cannabinoids components. For medical purposes, cannabinoid substances such as THC (Delta-9-tertrahydrocannabinol), CBD (cannabidiol) and non-cannabinoid substances such as terpenoids and flavonoids are relevant.
Medicinal cannabis must be distinguished from recreational cannabis which is used to achieve a psychotomimetic state of ‘high’. Cannabis strains used for recreational purposes contain a higher THC and lower CBD ratio than cannabis for medicinal use. Usually two cannabis plants are used: cannabis sativa which has a higher THC concentration and cannabis indica which has a higher CBD concentrate. The flavonoids are known for their antioxidant and anti-inflammatory effects. The terpenoids are resins (oil) with a strong odour.
In the 1990s, the endocannabinoid system (ESC) of the body was discovered by Raphael Mechoulam, an Israeli professor of medical chemistry. The endocannabinoid system, a central regulatory system, is the body’s largest receptor system and is important to maintain the homeostasis of the body.
Human beings produce their own cannabinoids (endocannabinoids) according to need and are not stored in the body. Like endorphins, the human body produces endocannabinoids in response to activities such as physical exercise (the high of runners might be due to endocannabinoids, not endorphins!).
Cannabinoid receptor type 1 (CB1) is mainly found in the brain, and also in the lungs, the reproductive organs, etc. Cannabinoid receptor type 2 (CB2) is usually located in the immune system and in the bones. THC mainly works on CB1 receptors, CBD on CB2 receptors.
In vitro studies with THC have shown that cannabinoids affect migration, angiogenesis and apoptosis (programmed cell death) of cancer cells, but each type of cancer appears to respond differently to the effect of exogenous cannabinoids. Many types of cancer cells have a higher concentration of CB1 and CB2 receptors.
Use of cannabis in cancer
– Pain: Cannabinoids have been used for centuries to lessen pain. Historical texts and old pharmacopoeia noted the use of cannabis for menstrual cramps, pain during childbirth, and headaches. Studies have shown that the cannabinoids have no effect on acute pain and post- operative pain. Two placebo-controlled studies with a cannabis extract showed modest benefits when using cannabinoids in addition to opioids and other adjuvant pain-killers in cancer patients with chronic pain. However, the effect of cannabinoids in chronic neuropathic pain was clearly demonstrated in 29 randomized studies.
– Nausea and vomiting: An initial study in 1975 showed a beneficial effect of THC on nausea induced by chemotherapy. Subsequently, two systematic reviews showed benefits of cannabinoids in nausea and vomiting due to chemotherapy, but most studies were observational or uncontrolled.
– Stimulation of appetite: Cannabinoids seem to have only a modest effect in cancer patients with cachexia. More promising results were seen in studies in the population without cancer.
– Pre-clinical studies (in vitro = cells in laboratory and in vivo = in mouse model) have shown the antiproliferative, anti-metastatic, anti-angiogenic and pro-apoptotic effects of cannabinoids in various malignancies (lung, glioma, thyroid, lymphoma, skin, pancreas, endometrium, breast and prostate). Even if an identified substance in vitro / in vivo appears to have a beneficial effect on a disease, it is important to realise that only one in 5,000-500,000 substances obtain a registration and becomes available to the patient (after 10-16 years of different study phases). Cannabis has never been clinically studied as a treatment for malignancy.
On the Internet, patients can get a lot of information about the curative effect of cannabis oil on prostate cancer but this information extrapolate the results of pre-clinical work to possible effects in people without any factual evidence. I often see patients in the doctor’s office showing me a website where it has been proven that cannabis oil can cure prostate cancer, which is obviously their own interpretation. In my view this can be a misleading message even though the website does not explicitly provide false information. The website [See figure below] shows information which is based on a study published in the British Journal of Cancer. This is correct, but the website “neglects” to mention that this is a publication of an in vitro study. The patient might not even know what an in vitro study is and is not aware that there are no studies on humans yet to prove this.
A challenge for the caregiver can be that the patient is convinced that we as healthcare practitioners work together with the pharmacists, and that we do not wish to carry out clinical trials (unfortunately, I hear that very often). We can hardly persuade patients that this is not true.
It is also important that we inform the patient about the possible interactions of cannabis oil with certain regular medications such as Coumarin (this blood thinner interacts with cannabis oil, leading to an increase of the INR and a greater risk of bleeding!). There are different types of cannabis oil available, such as CBD and THC oils with different concentrations which makes it difficult for patients to make a choice.
• There is no proof of cannabis oil as cure for prostate cancer;
• It is important not to be prejudiced or judgmental against patients who use cannabis oil;
• Listening to the patient’s view can be helpful since the patient often confides to the nurse rather than to their physicians;
• Avoid persuading patients not to use cannabis oil, but try to convince them of the need to follow a regular treatment combined with cannabis oil;
• Consider adverse interactions between cannabis oil and certain medications and inform your patient about these.
- Abrams, D.I. Integrating cannabis into clinical cancer care. Current Oncology, 23, S8-S14 (2016).
- Benzi Kluger, Piera Triolo, Wallace Jones, Joseph Jankovic. The Therapeutic Potential of Cannabinoids for Movement Disorders. Mov Disord. 2015 Mar; 30(3):313–327.
- Bowles, D.W, O’Brien, C.L, Camidge D.R, Jimeno A. The intersection between cannabis and cancer in the U.S. Critical Reviews in Oncology/Hematology, 83, 1-10 (2012).
- Bridgeman M.B and Abazia D. T. Medicinal Cannabis: History, Pharmacology, And Implications for the Acute Care Setting. P T. 2017 Mar; 42(3): 180–188.
- De Petrocellis L. et al. Non-THC cannabinoids inhibit prostate carcinoma growth in vitro and in vivo:pro-apoptotic effects and underlying mechanisms. Br J Pharmacol. 2013 Jan; 168(1): 79–102.
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- Machado Rocha F.C. et al. Therapeutic use of Cannabis Sativa on chemotherapy-induced nausea and vomiting among cancer patients: systematic review and meta-analysis. Eur. J. Cancer Care 2008;17:431-43.
- Olea-Herrero N. et al. Inhibition of human tumour prostate PC-3 cell growth by cannabinoids R(+)-Methanandamide and JWH-015: Involvement of CB2. British Journal of Cancer volume 101, pages 940–950 (15 September 2009).
- Portenoy R.K et al. Nabiximols for opioid-treated cancer patients with poorly-controlled chronic pain: a randomized, placebo-controlled, graded dose trial. J. Pain 2012;13:438-49.
- Ramos J.A. et al. The role of cannabinoids in prostate cancer: Basic science perspective and potential clinical applications. Indian J Urol. 2012 Jan-Mar; 28(1): 9–14.
- Tramer M.R. et al. Cannabinoids for control of chemotherapy induced nausea and vomiting: quantitative systematic review. BMJ 2001;323:16-21.
Corinne Tillier, Nurse Practitioner Urology, Antoni van Leeuwenhoek Hospital, Amsterdam (NL), [email protected]