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Original research
Assessment of mismatch repair deficiency in ovarian cancer
  1. Emma J Crosbie1,2,
  2. Neil A J Ryan1,2,3,
  3. Rhona J McVey4,
  4. Fiona Lalloo5,
  5. Naomi Bowers5,
  6. Kate Green5,
  7. Emma R Woodward3,5,
  8. Tara Clancy5,
  9. James Bolton4,
  10. Andrew J Wallace5,
  11. Raymond F McMahon4,
  12. D Gareth Evans3,5
  1. 1Division of Cancer Sciences, The University of Manchester, Manchester M13 9WL, UK
  2. 2Department of Obstetrics and Gynaecology, St Mary's Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, UK
  3. 3Division of Evolution and Genomic Medicine, The University of Manchester, Manchester M13 9WL, UK
  4. 4Department of Pathology, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, UK
  5. 5Manchester Centre for Genomic Medicine, North-West Genomics Laboratory Hub, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, UK
  1. Correspondence to Prof Emma J Crosbie, Division of Cancer Sciences, The University of Manchester, St Mary's Hospital, 5th floor- Research, Oxford Road, Manchester M13 9WL, UK; emma.crosbie{at}


Background Hereditary causes of ovarian cancer include Lynch syndrome, which is due to inherited pathogenic variants affecting one of the four mismatch repair genes involved in DNA repair. The aim of this study was to evaluate tumour mismatch repair deficiency and prevalence of Lynch syndrome in high-risk women referred to the Manchester Centre for Genomic Medicine with ovarian cancer over the past 20 years.

Methods Women with ovarian cancer diagnosed before the age of 35 years and/or with a suggestive personal or family history of Lynch syndrome cancers underwent tumour testing with immunohistochemistry for mismatch repair deficiency and, where indicated, MLH1 promoter methylation testing followed by constitutional testing for Lynch syndrome.

Results In total, 261 ovarian cancers were tested and 27 (10.3%; 95% CI 6.9% to 14.7%) showed mismatch repair deficiency by immunohistochemistry. Three of 7 with MLH1 loss showed MLH1 promoter hypermethylation, and 18 of the remaining 24 underwent constitutional testing for Lynch syndrome. A further 15 women with mismatch repair proficient tumours underwent constitutional testing because of a strong family history of Lynch syndrome cancers. Pathogenic variants were identified in 9/33 (27%) women who underwent constitutional testing, aged 33–59 years (median 48 years), including one whose tumour was mismatch repair proficient. Most Lynch syndrome tumours were of endometrioid histological subtype.

Conclusions Tumour mismatch repair deficiency identified by immunohistochemistry is a useful prescreen for constitutional testing in women with ovarian cancer with personal or family histories suggestive of Lynch syndrome.

  • genetic testing
  • surgical oncology
  • genetic predisposition to disease
  • gynecology

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  • Contributors DGE is the principal investigator for the study and its guarantor. EJC and DGE conceived the study. All authors contributed to data acquisition and interpretation. EJC and DGE wrote the first draft of the manuscript. All authors reviewed the manuscript and approved its final content.

  • Funding NAJR was a Doctoral Medical Research Council (MRC) Research Fellow (MR/M018431/1), DGE a National Institute for Health Research (NIHR) Senior Investigator (NF-SI-0513-10076), EJC a NIHR Clinician Scientist (NIHR-CS-012-009), and their work was supported through the NIHR Manchester Biomedical Research Centre (IS-BRC-1215-20007).

  • Disclaimer This article presents independent research funded by the NIHR and MRC. The views expressed are those of the authors and not necessarily those of the MRC, NHS, NIHR or the Department of Health.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available from the corresponding author on reasonable request.

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