Medical Cannabis, Prostate Cancer and Ovarian Cancer: A Look at the Research

Summary

There is a lot of promise surrounding medical cannabis and CBD and their potential to manage all sorts of cancers, including prostate or ovarian cancer. However, the strength of the evidence so far is low-to-moderate at best, and some harmful side-effects of smoked cannabis should be considered. We should not take promising preliminary evidence and individual case studies as proof that medical cannabis can help manage or treat prostate or ovarian cancer.

However, it is worth remembering that cancer is a systemic disease, and some may be responsive to cannabinoid treatment, others less so. There is much interest in the anti-inflammatory properties of cannabis to treat various types of cancer generally, as well as the management of side-effects like chemotherapy.

Introduction

September is both Ovarian Cancer and National Prostate Cancer Awareness Month. Although there are many differences between the two types of cancer, we thought it best to bring attention to both this September, asking “Could medical cannabis help manage the side effects of ovarian or prostate cancer treatment, and perhaps even be a way to target and kill cancerous cells?” The signs are positive, but before we answer this question, let’s take a look at what ovarian and prostate cancer are.

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What is Ovarian Cancer?

Ovarian cancer is a type of cancer that forms in the ovaries, where abnormal cells multiply quickly and invade and destroy healthy body tissue. Among women, ovarian cancer is the seventh-most common cancer and the eighth-most common cause of death from cancer. In 2015, ovarian cancer was present in 1.2 million women and resulted in 161,100 deaths worldwide. The American Cancer Society estimates that 12,810 women in the US will die from ovarian cancer in 2022.  In 2018, 4.4% (184,799 deaths) of total cancer-related mortality among women was attributed to ovarian cancer. Cervical cancer is a different type of cancer.

Ovarian cancer actually denotes a group of cancers that originate in the ovaries or in the related areas of the fallopian tubes and the peritoneum. Epithelial ovarian cancer is the most common type of cancer, with fallopian tube cancer and primary peritoneal cancer being less common but similar in cancer type and treatment. The most common tumor type is high-grade serous carcinoma, occurring in about 70% of ovarian cancer cases. Rare types of ovarian cancer include sarcomas, germ cell tumors (teratomas and dysgerminomas), and stromal tumors (granulosa tumors).

Mutations in the breast cancer susceptibility genes 1 and 2 (BRCA1 and BRCA2) and those associated with Lynch syndrome (a type of colon cancer, previously called hereditary non-polyposis colorectal cancer or HNPCC), raise ovarian cancer risk.

Symptoms of ovarian cancer include:

  • Abdominal bloating or swelling.
  • A frequent need to urinate.
  • Back pain.
  • Bloating.
  • Changes in bowel habits, such as constipation.
  • Discomfort in the pelvic area.
  • Fatigue.
  • Quickly feeling full when eating.
  • Weight loss.

Anyone with ovaries can get ovarian cancer, but it mostly affects those over 50, with the typical age of diagnosis being 63. Due to some of the symptoms of ovarian cancer (e.g., back pain, bloating and fatigue) being somewhat subtle and easily mistaken for other health problems (e.g. endometriosis), ovarian cancer can be diagnosed quite late. Moreover, existing screening tests like transvaginal ultrasound and laboratory markers like cancer antigen-125 (CA-125) assay make it difficult to detect ovarian cancer, as they are not reliable tests. There is certainly an argument to be made that alternative detection methods can be created, and doing so may also help detect other types of cancer in women.

a male and female reproductive organ models

How is Ovarian Cancer Treated?

The main two methods of treatment for ovarian cancer include:

  • Surgery to remove cancerous tissue. This can involve removing both ovaries, the womb and the tubes connecting them to each other (fallopian tubes).
  • Chemotherapy drugs like cisplatin (platinum-based chemotherapy), carboplatin and paclitaxel (Taxol). Chemotherapy may be used to shrink any tumors prior to surgery and/or be employed after surgery in order to get rid of any potential leftover cancer cells. Second-line chemotherapy drugs include topotecan.
  • Hormone therapy options like luteinizing hormones, tamoxifen and aromatase inhibitors.
  • Immunotherapy.

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What is Prostate Cancer?

Prostate cancer is a type of cancer that occurs in the prostate gland, which is found at the base of the bladder. Prostate cancer tends to affect men over 50, although it is possible to get it at any age (but very rare for those under 40). Prostate cancer tends to develop very slowly and is very difficult to test for, which can make it difficult to get early detection. In the U.S. there were about 268,490 new cases of prostate cancer and around 34,500 deaths from prostate cancer in 2022. The main risk factor for prostate cancer is age, but other factors like lack of physical activity, smoking, and obesity also increase the risk of prostate cancer.

The most common type of prostate cancer is adenocarcinoma of the prostate, of which there are two subtypes: acinar adenocarcinoma and ductal adenocarcinoma of the prostate. Other types of prostate cancer include transitional cell carcinoma of the prostate, squamous cell carcinoma of the prostate, small cell prostate cancer, and, more rarely, sarcoma or lymphoma that initially developed from the prostate.

Symptoms of prostate cancer include:

  • Blood in urine or semen.
  • Difficulty in starting to pee (hesitancy).
  • Dull pain in the pelvic area.
  • Feeling that your bladder has not emptied fully.
  • Needing to pee more frequently, often during the night.
  • Needing to rush to the toilet.
  • Straining or taking a long time while peeing.
  • Weak flow when urinating.

Due to how slowly prostate cancer grows, it is possible to live for years without symptoms arising or treatment being needed. However, this does not make the condition any less devastating, especially as prostate cancer is the second leading cause of cancer death in the U.S. after lung cancer.

In some countries prostate cancer kills more men than breast cancer kills women, which can be attributable to factors like age, lifestyle and socioeconomic status. Due to the difficulties in treating prostate cancer (e.g. the pain of having to go through chemotherapy during older age), less aggressive methods of treatment can help improve the lives of many men suffering from prostate cancer. Healthcare funding disparities could also play a role, but evidence for whether disparities favor men or women is mixed and varies between countries and conditions. (As can be seen in the difference in results here, here, here and here, but this argument is not the focus of this article.)

The most common tests for prostate cancer are:

  • Urine samples.
  • Digital rectal examination – literally the doctor inserting gloved fingers into your rectum.
  • Blood sample tests for prostate-specific antigen (PSA) levels. Raised levels of PSA are seen as a potential sign of prostate cancer.

Sadly, most methods of prostate cancer detection are uncomfortable and unreliable, making prostate cancer difficult to diagnose.

How is Prostate Cancer Treated?

Prostate cancer is treated by the following methods:

  • Surgery, which can involve removing parts of or the whole prostate gland.
  • Chemotherapy drugs like docetaxel (Taxotere) or cabazitaxel (Jevtana), which is often given in combination with the steroid prednisone.
  • Radiation therapy (radiotherapy).
  • Hormone therapy (e.g., androgen deprivation therapy, or ADT).
  • Immunotherapy.

How Might Medical Cannabis Help Manage Prostate or Ovarian Cancer?

This is difficult to answer for certain, as there is little research into this area. Existing research suggests that medical cannabis can be useful for helping manage several symptoms or side effects arising from cancer and chemotherapy treatment, including:

As for why medical cannabis can help treat some kinds of cancer, there are two main theories behind why, which do not necessarily compete with each other:

  1. Some evidence shows that cancer cells express cannabinoid receptors and that phytocannabinoids (plant cannabinoids) like tetrahydrocannabinol (THC) and cannabidiol (CBD) can bind to these receptors and instruct the cancerous cell to stop growing or even self-destruct (apoptosis). Cannabinoids do this by activating the production of a waxy, lipid molecule called “ceramide,” which regulates the differentiation, proliferation and death of cells. Activating ceramide production can shut down cancerous signaling pathways.
  2. Cannabis contains a plethora of anti-inflammatory compounds that can help reduce inflammation and help soothe an overactive immune system. As with many other health problems, inflammation plays a major part in the development of many types of cancer. Helping dampen it down can potentially help reduce the overall impact of the disease and reduce the spread of cancer cells.

When it comes to ovarian and prostate cancer specifically, it is difficult to say whether or not one or both of these theories is true as there is little research into this area. However, there is some research (mostly, and it is promising. For example, one case study found that a combination of laetrile (aka amygdalin, a bitter substance found in fruit pits, such as apricots, raw nuts, lima beans, clover, and sorghum) and CBD helped reduce the size of the mass growing inside the patient.

Another study shows that a combination of CBD and paclitaxel can inhibit tumor growth in those with ovarian cancer. Another case study reports a positive outcome with the mixture of medical cannabis (both CBD oil and Rick Simpson oil or RSO) and chemotherapy, helping the patient eat properly and overcome chronic pain. The precise mechanism as to why medical cannabis may work for patients with ovarian cancer is not known, but helping tame inflammation may be a big part of it.

There is a similar level of evidence for the use of medical cannabis for prostate cancer as there is for ovarian cancer: there is not much available, but the lab studies and anecdotal reports generally reflect positively. Prostate cancer cells contain cannabinoid receptors, including increased expression of CB1 and CB2 receptors. Activation of these receptors “results in a decrease in cell viability, increased apoptosis, and decreased androgen receptor expression and prostate-specific antigen excretion.”

Studies have shown that medical cannabis can help reduce the size of tumors in animals, but animals in the lab are different from people living in the real world. One study, for example, shows that there is an increased likelihood of developing prostate or testicular cancer in those who use cannabis regularly. These mixed results suggest that dosing, the type of cancer being treated, and the chemotype (i.e., the cannabinoids, terpenes, and flavonoids in cannabis) of the plant make a difference as to whether or not medical cannabis can help manage prostate cancer.

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Key Information and Takeaways

Ovarian Cancer

  • Total Studies = 8
  • Positive Studies = 8
  • Inconclusive Studies = 0
  • Negative Studies = 0
  • 5 Meta-Analyses (all positive); 3 Lab Studies (all positive)
  • 2 studies include CBD (both positive)
  • Possible Overall Efficacy: Low to moderate, due to the lack of human trials.

Prostate Cancer

  • Total Studies = 22
  • Positive Studies = 18
  • Inconclusive Studies = 4
  • Negative Studies = 0
  • 8 Meta-Analyses (5 positive, 3 inconclusive); 2 Animal Studies (both positive); 2 Human Trials (1 positive, 1 inconclusive); 10 Lab Studies (all positive)
  • 4 studies include CBD (all positive); 3 studies include THC (all positive); 1 study includes CBDA (positive); 1 study includes THCA (positive); 1 study includes CBG (positive); 1 study includes CBC (positive) 1 study includes CBN (positive); 1 study includes THCV (positive); 3 studies include Anandamide (all positive); 3 studies include 2-AG (all positive);
  • Possible Overall Efficacy: Low to moderate, due to the lack of proper human trials.

Potentially Useful Cannabis Compounds

Cannabinoids

  • Tetrahydrocannabinol (THC)
  • Cannabidiol (CBD)
  • Cannabigerol (CBG)
  • Cannabichromene (CBC)
  • Tetrahydrocannabivarin (THCV)
  • Cannabinol (CBN)
  • Cannabidiolic acid (CBDA)
  • Tetrahydrocannabinolic acid (THCA)

All of these cannabinoids have anti-inflammatory properties that may help reduce pain, anxiety, insomnia, appetite loss, and inflammation in those with many different types of cancer. CBD, in particular, has been shown to improve outcomes in those with ovarian cancer or prostate cancer.

Terpenes

Many terpenes have anti-inflammatory properties that could help reduce inflammation in those with cancer. Beta-caryophyllene, in particular, is a partial agonist of CB2 receptors, which can help reduce inflammation in areas where CB2 receptors are overexpressed.

Flavonoids

Flavonoids have been shown to have anti-inflammatory properties and could be used to regulate the immune system.

Potential Pros

  • Cannabis contains many anti-inflammatory compounds that can help reduce inflammation associated with some kinds of cancer.
  • Medical cannabis can help manage the side effects of cancer and chemotherapy.
  • Medical cannabis can reduce the need for stronger, more addictive painkillers.

Potential Cons

  • Avoid cannabis intake if you are undergoing immunotherapy. Existing research suggests that cannabis and cannabinoid treatment may reduce the efficacy of immunotherapy and potentially worsen clinical outcomes.
  • Some studies suggest that smoking cannabis can increase the likelihood of developing prostate or ovarian cancer, although cannabis may also inhibit tumor growth in prostate cancer if smoking is avoided and appropriate dosing regimes are developed. More research is needed on this subject.
  • No definitive evidence that cannabis works to manage or treat prostate or ovarian cancer, with some studies showing an increase in the likelihood of prostate or ovarian cancer.

Prostate and Ovarian Cancer infographic

Conclusion

There is a lot of promising evidence that medical cannabis and CBD may be useful for managing and possibly even treating ovarian or prostate cancer. However, the evidence that does exist is limited in that it is mostly lab data, case reports, or meta-analyses, which are good sources of information and evidence but do not have the same weight as a human trial (in particular a double-blind, placebo-controlled trial). This can make it difficult to say that medical cannabis can help manage prostate or ovarian cancer. The evidence that currently exists suggests that medical cannabis and CBD could be very useful for both types of cancer.