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A study into the biology of uterine Fibroids and Endometriosis at Oxford University.

FENOX is a prospective study that aims to improve our understanding of the underlying mechanisms of endometriosis and uterine fibroids and their associated symptoms by means of longitudinal observation and laboratory analyses.

Logo for the EndoCaRe Centre's FENOX Study.


Millions of women suffer from the consequences of endometriosis and uterine fibroids. These include pelvic and abdominal pain, abnormal uterine bleeding, infertility and miscarriages. As such, these conditions not only affect women and their families in their everyday lives, but also have been shown to have an enormous socioeconomic impact for society in general: In the United States, fibroids are cited to be the cause for over 50% of hysterectomies, and direct costs for their treatment is estimated to be $4-9 billion.

Clinically relevant, non-invasive diagnostic tests including biomarkers or imaging techniques do not exist for many forms of endometriosis resulting in an average delay in diagnosis of 8-12 years. Current treatment options are associated with significant side effects and risks and include hormonal suppression/modification, surgical removal or, in the case of fibroids, embolization and MRI guided focussed ultrasound (MRgFUS).

Therefore, there exists a significant unmet clinical need to better understand the underlying mechanisms of these conditions and conditions associated with endometriosis and uterine fibroids, which will enable us to develop more specific diagnostic tests and will eventually lead to individualised treatment, with fewer side effects and better efficacy. To achieve this goal, it is essential to collect prospective high quality, standardised clinical and intra-operative data and corresponding biological samples. Our group has been at the forefront of the development of standard operating procedures and questionnaires for endometriosis as part of the World Endometriosis Research Foundation’s (WERF) Endometriosis Phenome and Biobanking Harmonisation Project (EPHect), and we are planning to establish similar standards in uterine fibroid research.

In the FENOX (Fibroids and Endometriosis in Oxford) study, we aim to improve our understanding of the underlying mechanisms of endometriosis and uterine fibroids and their associated symptoms by means of longitudinal observation and laboratory analyses. To achieve this, samples and clinical data will be collected from women undergoing surgery. These samples will be used in state-of-the-art biomedical assays to improve our understanding of the underlying biology of these symptoms in women with endometriosis and/or fibroids, which will lead to a better understanding of the conditions, stratification of patient groups and tailored therapies, and the development of novel drug targets and biomarkers for diagnosis and treatment.

Women attending clinics or admitted for surgical treatment will be asked to participate in this study. Once consented, they are asked to complete detailed questionnaires at baseline and then at intervals (6-8 weeks, 6 months, 1 year and yearly, for a total of 5 years) about their symptoms, medications, co-morbidities, and ethnicity. Consenting women will also be asked to donate biological samples such as blood, urine and saliva at baseline and optionally, some of these again at a follow-up visit after their surgery, in addition to tissue taken at time of surgery.


  • To identify the underlying mechanisms of endometriosis and uterine fibroids and their associated symptoms to improve the outcome of affected women.
  • To identify novel biomarkers of endometriosis.
  • To identify clinical subgroups of endometriosis and uterine fibroids.
  • To understand the genetics underlying these conditions and explore the relevant downstream molecular pathways.
  • To investigate the relation between the presence of fibroids and the symptoms, e.g. abnormal uterine bleeding.
  • To identify novel drug targets.
  • To develop models of disease progression and prediction.
  • To investigate conditions or symptoms associated with endometriosis and/or uterine fibroids, including: symptoms and characteristics of the female reproductive system (characteristics of menstrual bleeding, fertility, infertility, pregnancy outcomes), pelvic as well as non-pelvic pain conditions, metabolic phenotypes (polycystic ovarian syndrome (PCOS), obesity and fat distribution), cardiovascular conditions and symptoms, neuroangiogenesis and related neurological symptoms, immunological disorders, and cancers.

Withdrawal of Participants from Study

Each participant has the right to withdraw from the study at any time. In addition, the Investigator may discontinue a participant from the study at any time if the Investigator considers it necessary for any reason including:

  • Pregnancy
  • Ineligibility (either arising during the study or retrospectively, having been missed at screening)
  • Withdrawal of Consent
  • Loss to follow up
  • Loss of mental capacity

If you would like to be withdrawn from the  study,  please contact us at:


Funding for this study has been obtained from the Nuffield Department of Women's and Reproductive Health under the Oxford/Bayer-Alliance for Women’s Health.