Cancer drugs could help end women’s monthly agony
As if your abdomen ‘is being singed with a red-hot poker’ is how one woman describes the pain of endometriosis. ‘Like someone is trying to prise you apart. it’s the worst pain imaginable,’ says another. And endometriosis doesn’t just cause debilitating pain — it is also a leading cause of infertility.
Yet although about 1.5 million women in the UK are affected, endometriosis has long been a Cinderella condition.
Earlier this month, in a letter published in The Lancet, women with endometriosis called for more research.
‘Endometriosis has received little funding because it only affects women and there remains a gender bias in research,’ says Andrew Horne, a professor of gynaecology and reproductive sciences at the University of Edinburgh.
‘ it has also suffered because it is an “invisible” chronic pain condition — it’s not like having a broken leg for example — and other people struggle to envisage what it’s like to live with.’
Endometriosis occurs when the tissue that normally forms the lining of the womb each month occurs elsewhere in the body.
This can cause pain, as every month the tissue is expelled at the time of menstruation, but has nowhere to go.
it also triggers inflammation, which can lead to the development of scar tissue that sticks to internal organs, causing even more pain. if endometriosis forms around the reproductive organs, it can affect fertility.
famous sufferers include Marilyn Monroe, who is believed to have become addicted to the painkillers prescribed to help with the condition. it’s also thought to have contributed to her difficulties conceiving.
Hormonal drugs can help reduce symptoms by lowering the levels of oestrogen (the hormone is thought to encourage endometriosis), but this can trigger menopause-like side-effects. There are surgical options to cut or burn away the tissue. However, it regrows in as many as three out of four women, according to some experts.
in desperation some women opt for a hysterectomy, but even this does not solve the problem for all.
But new options may be on the horizon with the discovery that endometriosis cells behave much like cancer cells.
scientists now hope to exploit that similarity and use cancer drugs to treat the condition.
A study published a fortnight ago in the New England Journal of Medicine found that some forms of endometriosis show genetic cancer-like changes.
Canadian scientists studied tissue from the wombs of 39 women with a type of endometriosis called deep-infiltrating, a relatively rare form of the disease that, as the name implies, pushes deep within tissue.
‘The results are interesting as they found that the endometriosis had a number of the gene mutations that you would see with cancer — but not enough for it to become a cancer,’ says Professor Horne.
The news is of particular interest to Professor Horne as he and his team at Edinburgh University are testing cancer drugs as a treatment for a more common form of endometriosis.
The new treatment will target endometriosis in the peritoneum — the lining of the pelvis — which is where the condition occurs in 80-90 per cent of cases (although it can affect many areas in the body, from around the bowel to the lungs).
‘ The endometriosis tissue invades the peritoneum, sticks to it and forms its own blood supply in much the same way cancer cells would do,’ says Professor Horne.
‘And we have found that the cells in the peritoneum of women with endometriosis differ metabolically (i.e. in the way they produce energy) from cells in women without it.
‘They produce energy in a similar way cancer cells do.’
Normally cells break down sugars in their mitochondria — the energy packs within the cells. Cancer cells instead switch off their mitochondria and break down sugars in the cytoplasm — the main area of the cell. This is known as the Warburg effect.
The cells in the pelvis of women with endometriosis also behave in this way. Professor Horne and his team have been testing cancer drugs that switch off the Warburg effect.
These are dichloroacetate, a drug that has been used for years for another condition, lactic acidosis, and is being tested on those with brain tumours; galloflavin, which is also being tested for breast cancer; and gossypol, currently being tested for use in breast and prostate cancer.
‘ We have done lots of tests with promising results — it seems that we can change the endometriosis cells back to normal cells,’ adds Professor Horne.
so far the research, funded by the charity Wellbeing of Women, has been carried out on donated tissue collected from women with endometriosis.
But the researchers are starting to test the treatments on mice, too, to help see if they reduce the pain of the condition, says Professor Horne.
it’s envisaged that the drugs would be offered in the early stages of the disease to prevent widespread painful growths and would be given in far smaller doses than may be used for cancer to minimise the side- effects. Dichloroacetate, for example, can cause numbness and fatigue.
‘The treatment for endometriosis may be given as tablets but it would need to be taken every day,’ adds Professor Horne. ‘Another option would be to give it as a vaginal ring or coil that slowly releases small amount of the drug.’
He hopes to start trials on women within a year.
if successful, the research could have wider implications.
‘A respected endocrinologist once said to me: “When we find a cure for endometriosis, we’ll be able to cure cancer,” ’ says Lone Hummelshoj, chief executive of the World Endometriosis Research foundation.
Hugh Byrne, a consultant gynaecologist at st George’s and the Lister Hospitals in London, welcomes the cancer drug research. ‘There is a need for more options for women with endometriosis and this approach makes sense,’ he adds.
‘Endometriosis does behave like a cancer: it spreads around the body, invades and destroys local tissue, and is sporadic in that it affects some women and not others.
‘However, this is early stage research and we need far more data.’
7 1⁄ 2 Average number of years it takes after first symptoms to get an endometriosis diagnosis