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EXPPECT research highlights

This page summarises the EXPPECT group’s latest research, research highlights, and key research priorities for endometriosis.

Gabapentin for chronic pelvic pain in women (GaPP2): a multicentre, randomised, double-blind, placebo-controlled trial

In September 2020, the EXPPECT-led GaPP2 trial was published in The Lancet.

What did the study show and what does it mean?

Treatment with gabapentin did not result in significantly lower pain scores in women with chronic pelvic pain, and was associated with higher rates of side-effects than placebo. Given the increasing reports of abuse and evidence of potential harms associated with gabapentin use, it is important that clinicians consider alternative treatment options to off-label gabapentin for the management of chronic pelvic pain and no obvious pelvic pathology.

Repurposing dichloroacetate for the treatment of women with endometriosis

Researchers, led by Andrew Horne and Philippa Saunders, from the University of Edinburgh found that cells from the pelvic wall of women with endometriosis have different metabolism compared to women without the disease. The cells produced higher amounts of lactate similar to the behavior of cancer cells. When the cells from women with endometriosis were treated with dichloroacetate, they were found to return to normal metabolic behavior. The scientists also noted a reduction in lactate and an impact on the growth of endometrial cells grown together with the pelvic cells. Further tests on a mouse model of endometriosis found, after seven days, a marked reduction in lactate concentrations and the size of lesions.

This research was published in the Proceedings of the National Academy of Sciences (PNAS) in December 2019.

This publication received widespread media attention, including:

Read their research article.

Surgical removal of superficial peritoneal endometriosis for managing women with chronic pelvic pain: time for a rethink?

In August 2019, Professor Horne and colleagues published an article in BJOG regarding management of superficial peritoneal endometriosis (SPE).

In conclusion, we believe that it is crucial for policy makers, funding bodies, researchers, clinicians, and women with endometriosis to work together in a ‘precision medicine ecosystem’ to build a knowledge base that can determine whether SPE is better suited to surgical, multimodal or conservative treatment, to guide and improve individualised patient care.

Professor Horne and colleaguesArticle authors

Read their article.

Don't over exaggerate the low risk of ovarian cancer for women with endometriosis 

In December 2017, Professor Horne and colleagues published an article in The Lancet highlighting the importance of doctors communicating effectively the low increase in risk of ovarian cancer for women with endometriosis - to avoid needlessly scaring women or potentially recommending unnecessary treatments.

Over the last few years, there has been increasing concern amongst women with endometriosis about their risk of ovarian cancer and this has been aggravated a misinterpretation of the data to support the link. I hope that our analysis of the data and the messages presented in this article will provide clarification, reassurance and reduce unnecessary (and potentially risky) preventative intervention measures.

Professor Andrew Horne

Ovarian cancer in the general female population has a rate of 1.3%, for women with endometriosis it is 1.8% - still a low risk in overall terms and not much different to that of the general population.

Endometriosis UK welcomes the clarification published in The Lancet that endometriosis comes with only a very small increase in the risk of ovarian cancer, and hope all Doctors and those writing about the link will now find it easier to communicate this appropriately. Women suffer for an average of 7.5 years before receiving a diagnosis of endometriosis, and during this time their symptoms may have been misdiagnosed or ignored as 'not significant' - being told to 'get on with it' or 'it's all in your head' is not uncommon. There is a lot to take in when finally getting a diagnosis - how to manage the pain, treatment and surgical options, and impact on fertility. Adding unnecessary cancer scares is unhelpful and detracts from a woman being able to decide about the best way to manage her disease.

Emma CoxChief Executive of Endometriosis UK


My doctor told me that I had an increased risk of ovarian cancer as I have endometriosis. I was fast tracked for two scans, internal examinations and extra blood tests, then given an emergency appoint to see a cancer specialist in a cancer centre the following week. I was really worried, it was a big scare for me and my family. The cancer specialist was very reassuring that there was nothing wrong, although he seemed surprised at what had happened and why I was there. When he explained there was only a very small increase for me in the risk of ovarian cancer – 0.5% - I was shocked. I’d been given the impression the risk was massive.

Amanda (woman with endometriosis)

Results of the Endometriosis Priority Setting Partnership

In May 2017, the results of the Endometriosis Priority Setting Partnership led by Andrew Horne and Philippa Saunders from the University of Edinburgh, and overseen by the James Lind Alliance—a non-profit initiative funded by the National Institute for Health Research — were published in The Lancet with a commentary in The BMJ, and highlighted in the national press:
Patients and clinicians agreed that improving the diagnosis of endometriosis and stopping its progression are key research priorities for the condition.