For tens of thousands of women, a diagnosis of endometriosis means a life of debilitating pain.
Despite it affecting one woman in ten in the UK, from teenagers through to middle age, treatment options remain limited.
There is no cure and the available treatments often have significant side-effects, affecting fertility, for example, because they contain hormones.
Now a hormone-free device, which would circumvent many of the side-effects associated with existing options, is being suggested as a new treatment — and the results so far look promising.
For tens of thousands of women, a diagnosis of endometriosis means a life of debilitating pain. Despite it affecting one woman in ten in the UK, from teenagers through to middle age, treatment options remain limited
Endometriosis occurs when cells similar to those found in the lining of the womb occur elsewhere in the body — commonly within the pelvis.
These cells behave like those in the womb, each month building up and then breaking down and bleeding as part of the menstrual cycle.
However, when they build up outside the womb, these cells cause pain and inflammation and can lead to scarring.
Women with endometriosis often have very painful periods as well as pelvic pain at other times of the month, and it can also cause a range of other conditions, including infertility, bowel and bladder problems caused by scarring, as well as fatigue and mental health and relationship difficulties.
The endometrial tissue can be removed surgically but this is only effective in about a quarter of patients, and 50 per cent have a recurrence of their symptoms within five years of an operation.
The other main option is hormone medication. As endometriosis tissue grows when exposed to the female hormone oestrogen, treatments that block or reduce the production of oestrogen from the ovaries are often used, such as the Pill, the Mirena coil and gonadotrophin-releasing hormone (GnRH) injections (brand name Zoladex).
But these don’t work for everyone and have side-effects such as nausea, headaches and mood changes.
Endometriosis occurs when cells similar to those found in the lining of the womb occur elsewhere in the body — commonly within the pelvis
They are also unsuitable for women who want to start a family and symptoms usually return once hormonal medication is stopped.
The latest solution, the drug dichloroacetate (DCA), is already used to treat rare metabolic conditions in children and is being investigated as a possible treatment for certain cancers.
DCA works by blocking changes in the metabolic processes of cells (which occur in the mitochondria, the powerhouse of a cell, that control how they produce energy); the drug effectively restores cell function to normal.
In 2019, researchers from the University of Edinburgh found that cells from the pelvic wall of women with endometriosis have a different metabolism. The cells in the pelvic wall produced higher amounts of lactate — a chemical by-product of metabolism.
The scientists believe lactate may encourage the growth of abnormal endometrial cells (similar to the behaviour of cancer cells, which is why the drug is also being investigated as a cancer treatment).
When the Edinburgh team tested DCA in mice, after seven days it reduced levels of lactate and the size of endometriosis lesions.
Now the researchers are trialling the drug on 30 women with the most common type of endometriosis, superficial peritoneal disease, which affects the lining of the pelvis and accounts for 80 to 90 per cent of cases.
Because the drug does not contain hormones, it should avoid the side-effects associated with conventional treatments.
In the trial, each woman has a dose of DCA matched to her weight, twice a day for six weeks, and patients record their pain.
If the women, who know they are taking DCA (as it is an early study, instead of a blinded one), feel it is working, they can take it for another six weeks. As this form of endometriosis can’t be seen on a scan, researchers rely on symptoms reported by the women.
Andrew Horne, a professor of gynaecology and reproductive sciences at the university, who is leading the research, says the majority of women report an improvement in their symptoms.
However, some have reported nausea and, when they stop taking it, the symptoms recur.
Full results are expected this summer and the researchers hope to launch a bigger trial next year comparing it with women taking a placebo. If the trials are successful, then to avoid taking a daily pill women could use a device containing DCA.
‘As women have to keep taking dichloroacetate to get the benefits, one option we are looking at is a vaginal ring which contains the drug and delivers a steady dose,’ says Professor Horne.
‘This might be changed once a week and would be ideal as women wouldn’t have to remember to take tablets every day.
‘Also, because a vaginal ring would deliver the drug direct to the pelvis, we hope it would reduce any side-effects.’
Denis Tsepov, a consultant gynaecologist at The Harley Street Clinic in London, says there is a real need for more treatments. ‘Dichloroacetate can potentially reduce the symptoms and slow the progression of the disease and we welcome this new research,’ he says. ‘But, it is still experimental.’
Another study at the University of Oxford identified genetic links between endometriosis and inflammatory conditions like asthma, osteoarthritis, migraines and back pain.
This raises the prospect that drugs used to treat these conditions, such as anti-inflammatories, may work for endometriosis, too.