Exploring medicinal cannabis in endometriosis

Endometriosis is a notoriously painful condition affecting more than 11% of Australian women. The condition is characterised by the growth of endometrial tissue (which normally lines the uterus) outside the uterus. Seedings of endometrial tissue can occur in the lining of the pelvis, the abdomen, ovaries, bowel and in uterine muscle (known as adenomiosis). The pain associated with endometriosis often follows a cyclical pattern, in line with a woman’s menstrual cycle. Seedings of tissue can flare up around the time of menstruation, causing pain, which for some is excruciating and debilitating, leaving sufferers bedridden for days. For some women with endometriosis, pain can occur between cycles and/or during intercourse, invading and disrupting important aspects of life.

A range of treatment options are currently deployed for endometriosis, including analgesics such as paracetamol, application of heat packs to the site of pain, over-the-counter and prescription anti-inflammatories, and medications that regulate hormonal regulation, such as the oral contraceptive pill, or progestogen-only pill. If these treatments are not successful, options such as gonadotropin-releasing hormone (Gn-RH) agonists and antagonists might be used to block the production of estrogen and induce an artificial menopause.

Dr Mark Hardy is an addiction medicine specialist with broad experience in treating endometriosis. He explained that while higher-ended treatments can help to control symptoms, they come with increased side effects.

“Chemically inducing menopause can result in hot flashes, vaginal dryness and irritability, as well as increasing the risk of osteoporosis,” he said.

“Surgical treatments are available for women with a large burden of endometriosis, involving the removal of endometriomas via a laparoscopic procedure. This sees the endometrial tissue removed via a laser or a diathermy blade. This option can have good results, but comes with risks of damaging healthy tissue and causing scar tissue adhesions to areas such as the bowel and fallopian tubes, which can worsen pain and result in other complications. Unfortunately, for some women, the endometriosis comes back, so in certain circumstances a combination of treatments is needed.”

Addiction medicine specialist Dr Mark Hardy has broad experience in treating endometriosis.

Could medicinal cannabis help?

Interest in medicinal cannabis is growing among Australian doctors and patients — in particular, its ability to treat conditions such as chronic pain. Medicinal cannabis is currently used as an adjunct treatment and management option for refractory chronic pain, a common symptom of endometriosis.

Applied Cannabis Research is conducting an observational study through CA Clinics, investigating medicinal cannabis for the treatment of endometriosis. The study aims to recruit 200 women — who will be followed up for 12 months — and will collect safety and efficacy data, as well as track pain and quality-of-life outcomes. The observational study is a sub-study of the CA Clinics Observational Study (CACOS), which aims to collect data on medicinal cannabis for a range of hard-to-treat conditions.

“Research shows that women with endometriosis often may wait up to eight years before they receive a diagnosis,” said Louis Williams, CEO of Aruma Labs, which will include its medicinal cannabis products in the study. “During that time, they can suffer debilitating pain, depression and a diminished quality of life. Our aim, through this partnership with Applied Cannabis Research, is to collect patient-reported data to understand whether our unique formulations have potential as a safe and effective treatment option in the ongoing management of the pain that often accompanies endometriosis.”

“Chronic pain associated with endometriosis is a complex and debilitating problem for millions of women worldwide,” Dr Hardy added. The positive impacts of medical cannabis on pain are potent enough to consider medical cannabis as a pain-management option, adjunct to current treatments.”

Dr Hardy explained that the study will examine different constituents of medicinal cannabis: Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). CBD most likely works via an anti-inflammatory pathway; THC is thought to have a direct effect on pain via cannabinoid receptors in the brain and other parts of the body.

“For women with crippling pain caused by endometriosis, cannabinoids could have something to offer, and this is something that we want to find out. Medicinal cannabis is not a panacea, but could have an important role in adjunctive treatment,” he said.

“In severe endometriosis, I often see women who have to take large quantities of analgesics just to get through the day. This can lead to tolerance; dependence; problems with the liver, kidneys and stomach; and loss of functional capacity.

“Cannabinoids have the advantage of being opioid sparing, with far less chance of overdose compared with opioids.”

CA Clinics’ Dr Davina Hiley added, “Many women suffer from distressing endometriosis symptoms. Common treatments such as hormonal therapy, analgesia, anti-inflammatories or even surgical intervention are often ongoing, and have their own set of risks and side effects. There’s therefore a need to consider other therapeutic management options such as medicinal cannabis.”

The CACOS endometriosis sub-study will investigate the safety and efficacy of a THC-dominant product, a CBD-dominant product and a balanced THC–CBD product. Optimal dosing and constituent profiles will be assessed over the 12-month follow-up period by monitoring factors such as pain scores, pain interference, sleep patterns and welfare.

“At this point we don’t know if any of the cannabinoids will work, but that’s what we want to find out,” Dr Hardy said. “Do patients find that their pain gets better? Are people coping better as a result of taking this medication? What constituents work best and how do they work in combination with other strategies such as hormone treatments or surgery? Having a real-world observational study of this kind will inform us how the treatment behaves in the community and will be very useful in generating data on an area of medicine that is relatively unexplored. We will be hanging out for the results.”

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