Multicenter evaluation of blood-based biomarkers for the detection of endometriosis and adenomyosis: A prospective non-interventional study.

OBJECTIVE: To evaluate blood-based biomarkers to detect endometriosis and/or adenomyosis across nine European centers (June 2014-April 2018). METHODS: This prospective, non-interventional study assessed the diagnostic accuracy of 54 blood-based biomarker immunoassays in samples from 919 women (aged 18-45 years) with suspicion of endometriosis and/or adenomyosis versus symptomatic controls. Endometriosis was stratified by revised American Society for Reproductive Medicine stage. Symptomatic controls were "pathologic symptomatic controls" or "pathology-free symptomatic controls". The main outcome measure was receiver operating characteristic-area under the curve (ROC-AUC) and Wilcoxon P values corrected for multiple testing (q values). RESULTS: CA-125 performed best in "all endometriosis cases" versus "all symptomatic controls" (AUC 0.645, 95% confidence interval [CI] 0.600-0.690, q < 0.001) and increased (P < 0.001) with disease stage. In "all endometriosis cases" versus "pathology-free symptomatic controls", S100-A12 performed best (AUC 0.692, 95% CI 0.614-0.769, q = 0.001) followed by CA-125 (AUC 0.649, 95% CI 0.569-0.729, q = 0.021). In "adenomyosis only cases" versus "symptomatic controls" or "pathology-free symptomatic controls", respectively, the top-performing biomarkers were sFRP-4 (AUC 0.615, 95% CI 0.551-0.678, q = 0.045) and S100-A12 (AUC 0.701, 95% CI 0.611-0.792, q = 0.004). CONCLUSION: This study concluded that no biomarkers tested could diagnose or rule out endometriosis/adenomyosis with high certainty.

Endometriosis in women undergoing ovarian tissue transplantation due to premature menopause after gonadotoxic treatment or spontaneous premature ovarian failure.

INTRODUCTION: Cryopreservation of ovarian tissue with subsequent transplantation is an efficient option for restoring fertility in women at risk of premature ovarian failure. The association between infertility and endometriosis is well recognized. Although endometriosis usually ends with the onset of natural or iatrogen menopause due to declining estrogen levels, endometriosis can in rare cases occur after menopause. This study aims to investigate women with premature menopause who were diagnosed with endometriosis during laparoscopy for ovarian tissue transplantation, and to address the questions of how endometriotic lesions after cytotoxic treatment and premature menopause might be explained, whether endometriosis affects pregnancy rates, and whether there is an association between endometriosis and the original cancer. MATERIAL AND METHODS: Seventeen patients who had undergone ovarian tissue transplantation to restore their fertility and who were diagnosed with endometriosis during transplantation were included in this retrospective study. The endometriosis foci were completely removed and ovarian tissue was transplanted into the pelvic peritoneum. Preexisting conditions, use of hormonal preparations, endometriosis stage pain assessment, as well as pregnancy and live birth rate were evaluated. RESULTS: The mean age of the patients was 29.5 ± 6.3 years (range 14-39) at the time of ovarian tissue harvest and 34.6 ± 4.3 years (range 28-40) at transplantation. Prior to transplantation, four patients had taken hormone replacement therapy, four women oral contraceptives and two patients' tamoxifen. Twelve women had stage I endometriosis and five stage II endometrioses according to the rASRM classification. Four patients reported dysmenorrhea. None of the women complained of general pelvic pain or dyspareunia. The pregnancy rate in the study population was 41.2%, with a live birth rate of 35.3%. The pregnancies occurred in three cases after spontaneous conception, in four women after a natural cycle IVF/ICSI. CONCLUSIONS: This study highlights the under-researched association between endometriosis in women entering premature or early menopause either after gonadotoxic treatment or due to primary ovarian insufficiency. As more and more patients seek to have their cryopreserved ovarian tissue transplanted to fulfill their desire to have children, specialists will inevitably encounter women with this condition.

Comprehensive characterization of endometriosis patients and disease patterns in a large clinical cohort.

PURPOSE: In many diseases, it is possible to classify a heterogeneous group into subgroups relative to tumor biology, genetic variations, or clinical and pathological features. No such classification is available for endometriosis. In our retrospective case-case analysis we defined subgroups of endometriosis patients relative to the type and location of the endometriosis lesion and relative to basic patient characteristics. METHODS: From June 2013 to July 2017, a total of 1576 patients with endometriosis diagnosed at surgery were included in this study. The patients' history and clinical data were documented using a web-based remote data entry system. To build subgroups, all possible combinations of endometriosis locations/types (peritoneal; ovarian endometriosis; deeply infiltrating endometriosis; adenomyosis) were used. Due to the variation in group sizes, they were combined into five substantial larger groups. RESULTS: Age, pregnancy rate, and live birth rate were identified as characteristics that significantly differed between the five patient groups that were defined. No significant differences were noted in relation to body mass index, length of menstrual cycle, age at menarche, reason for presentation, or educational level. CONCLUSION: This study describes basic patient characteristics in relation to common clinical subgroups in a large clinical cohort of endometriosis patients. Epidemiological information about different clinical groups may be helpful in identifying groups with specific clinical courses, potentially suggesting novel approaches to early detection and to surgical and systemic treatment.

[S2k guidelines for the diagnosis and treatment of endometriosis-Recommendations for pathology]. / S2k-Leitlinie Diagnostik und Therapie der Endometriose ­ Anforderungen an die Pathologie.

The present article summarises the recommendations for the handling, histopathological workup, diagnostics and reporting in surgical pathology of biopsies and resection specimens in patients with the clinical diagnosis of endometriosis. In addition to practical aspects of pathology, the guidelines also take into account the clinical requirements for histopathology for the optimal diagnosis and therapy of the patients.Based on the definition of endometriosis of the corpus uteri (adenomyosis uteri) most commonly used in the pathological literature, this was defined in the guidelines as the detection of the endometriosis focus in the myometrium at a distance from the endomyometrial border of a medium-sized visual field (100× magnification), which in metric units corresponds to around 2.5 mm. In bowel resection specimens, the status of the resection margins had to be documented within the histopathological report.Also mentioned are the requirements for the reporting of carcinomas associated with endometriosis, including the immunohistochemical evaluation of steroid hormone receptors and mismatch repair proteins.

Comparison of methods for isolation and quantification of circulating cell-free DNA from patients with endometriosis.

RESEARCH QUESTION: Which is the optimal extraction method for isolating and quantifying circulating cell-free DNA (ccfDNA) from patients with endometriosis? Endometriosis is a common benign disease, associated with pain, infertility and reduced quality of life. Endometriosis is also a known risk factor for various cancers. Robust biomarkers for early detection and prediction of prognosis, however, are lacking. CcfDNA is an easy to obtain biomarker associated with prognosis of cancer patients and enables non-invasive analysis of somatic mutations. Recently, elevated levels of ccfDNA were detected in patients with endometriosis. DESIGN: Two different ccfDNA extraction methods were compared: Maxwell RSC ccfDNA plasma kit (Maxwell) and QiAamp minElute ccfDNA mini kit (QIAamp). The ccfDNA and circulating mitochondrial DNA (mtDNA) quantities from 34 patients diagnosed with endometriosis were analysed. Fluorometric measurement and quantitative reverse transcription polymerase chain reaction (qRT-PCR) of short and long ALU and mtDNA fragments were used to quantiy ccfDNA. RESULTS: The yield of ccfDNA isolated with the Maxwell method was significantly higher compared with the QIAamp method (P < 0.0001). Integrity of ccfDNA was significantly higher in the QIAamp isolate (P < 0.0001). Recovered mtDNA was not significantly different between both extraction methods used. CONCLUSIONS: The choice of extraction method can significantly influence the ccfDNA output and integrity. Both methods, however, enabled isolation of sufficient ccfDNA for further downstream applications. With this approach, isolation of ccfDNA could enable the non-invasive detection and analysis of somatic mutation within endometriosis tissue.

Diagnosis and Treatment of Endometriosis. Guideline of the DGGG, SGGG and OEGGG (S2k Level, AWMF Registry Number 015/045, August 2020).

Aims The aim of this official guideline published and coordinated by the German Society of Gynaecology and Obstetrics (DGGG) in cooperation with the Austrian Society for Gynaecology and Obstetrics (OEGGG) and the Swiss Society for Gynaecology and Obstetrics (SGGG) was to provide consensus-based recommendations for the diagnosis and treatment of endometriosis based on an evaluation of the relevant literature. Methods This S2k guideline represents the structured consensus of a representative panel of experts with different professional backgrounds commissioned by the Guideline Committee of the DGGG, OEGGG and SGGG. Recommendations Recommendations on the epidemiology, aetiology, classification, symptomatology, diagnosis and treatment of endometriosis are given and special situations are discussed.

[Endometriosis: gynecological diagnosis and treatment : What should pain management specialists know?] / Endometriose ­ gynäkologische Diagnostik und Therapie : Was sollten Schmerzmediziner*innen wissen?

BACKGROUND: Endometriosis is one of the most common diseases in women of reproductive age. Despite characteristic symptoms such as dysmenorrhea, chronic abdominal pain, dysuria, dyschezia and dyspareunia, the average latency until diagnosis is around 10 years. In addition to the individual limitations, the disease also has economic and health policy relevance. The complaints are followed by reductions in working hours, cyclically recurring short-term sick leave or presenteeism with reduced performance. OBJECTIVE: An overview of the main recommendations of the S2k guideline on the diagnosis and treatment of endometriosis. MATERIAL AND METHODS: For the S2k guideline "Diagnostics and therapy of endometriosis", a systematic literature search was conducted in PubMed and Cochrane according to a defined algorithm and over a period of more than 5 years, from 01.01.2014 to 31.12.2018. For the evaluation, 322 publications, including systematic reviews, meta-analyses and randomized controlled trials were considered and these were assessed by 41 mandate holders and representatives from 25 Association of the Scientific Medical Societies in Germany (AWMF) and non-AWMF professional societies, organizations, associations and working groups of the German Society for Gynecology and Obstetrics (DGGG), as well as two patient target groups. RESULTS: In a structured consensus process, 48 recommendations and 27 statements were formulated, which are presented in extracts in this paper. DISCUSSION: Interdisciplinary cooperation is essential in the treatment of patients with (suspected) endometriosis. This team should include all necessary disciplines in a cross-sectoral network. This is most likely to be achieved in a certified structure.

Cross-Cancer Genome-Wide Association Study of Endometrial Cancer and Epithelial Ovarian Cancer Identifies Genetic Risk Regions Associated with Risk of Both Cancers.

BACKGROUND: Accumulating evidence suggests a relationship between endometrial cancer and ovarian cancer. Independent genome-wide association studies (GWAS) for endometrial cancer and ovarian cancer have identified 16 and 27 risk regions, respectively, four of which overlap between the two cancers. We aimed to identify joint endometrial and ovarian cancer risk loci by performing a meta-analysis of GWAS summary statistics from these two cancers. METHODS: Using LDScore regression, we explored the genetic correlation between endometrial cancer and ovarian cancer. To identify loci associated with the risk of both cancers, we implemented a pipeline of statistical genetic analyses (i.e., inverse-variance meta-analysis, colocalization, and M-values) and performed analyses stratified by subtype. Candidate target genes were then prioritized using functional genomic data. RESULTS: Genetic correlation analysis revealed significant genetic correlation between the two cancers (rG = 0.43, P = 2.66 × 10-5). We found seven loci associated with risk for both cancers (P Bonferroni < 2.4 × 10-9). In addition, four novel subgenome-wide regions at 7p22.2, 7q22.1, 9p12, and 11q13.3 were identified (P < 5 × 10-7). Promoter-associated HiChIP chromatin loops from immortalized endometrium and ovarian cell lines and expression quantitative trait loci data highlighted candidate target genes for further investigation. CONCLUSIONS: Using cross-cancer GWAS meta-analysis, we have identified several joint endometrial and ovarian cancer risk loci and candidate target genes for future functional analysis. IMPACT: Our research highlights the shared genetic relationship between endometrial cancer and ovarian cancer. Further studies in larger sample sets are required to confirm our findings.

Targeted sequencing of FH-deficient uterine leiomyomas reveals biallelic inactivating somatic fumarase variants and allows characterization of missense variants.

Uterine leiomyomas (ULs) constitute a considerable health burden in the general female population. The fumarate hydratase (FH) deficient subtype is found in up to 1.6% and can occur in hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome. We sequenced 13 FH deficient ULs from a previous immunohistochemical screen using a targeted panel and identified biallelic FH variants in all. In eight, we found an FH point mutation (two truncating, six missense) with evidence for loss of the second allele. Variant allele-frequencies in all cases with a point mutation pointed to somatic variants. Spatial clustering of the identified missense variants in the lyase domain indicated altered fumarase oligomerization with subsequent degradation as explanation for the observed FH deficiency. Biallelic FH deletions in five tumors confirm the importance of copy number loss as mutational mechanism. By curating all pathogenic FH variants and calculating their population frequency, we estimate a carrier frequency of up to 1/2,563. Comparing with the prevalence of FH deficient ULs, we conclude that most are sporadic and estimate 2.7-13.9% of females with an FH deficient UL to carry a germline FH variant. Further prospective tumor/normal sequencing studies are needed to develop a reliable screening strategy for HLRCC in women with ULs.

Standards Used by a Clinical and Scientific Endometriosis Center for the Diagnosis and Therapy of Patients with Endometriosis.

Endometriosis is one of the most common benign gynecological diseases. The extremely heterogeneous complex of symptoms complicates the diagnosis and treatment of this disease. In most patients, there is a latency period of several years between the first occurrence of symptoms and the definitive diagnosis. This paper aims (1) to evaluate standards for the diagnosis and treatment of patients with (symptoms suspicious for) endometriosis in terms of feasibility, and (2) to assess the potential use of data collected by a certified clinical and scientific endometriosis center to answer scientific questions. Standards for outpatient consultations were developed for a special endometriosis outpatient clinic. Between January 2014 and December 2017, a total of 1715 outpatients with a suspicion of endometriosis presented to this special endometriosis outpatient clinic; the diagnosis and treatment of patients was carried out in accordance with the developed standards. Data of this patient cohort obtained from patient records created during outpatient consultations and from a questionnaire recorded in an Oracle-based database was analyzed. The patient cohort was also compared with another patient cohort who had attended different outpatient clinics and had been diagnosed intraoperatively with endometriosis. 41.8% of patients examined during special outpatient consultations had surgery for suspicion or recurrence of endometriosis. Endometriosis was confirmed in 81.5% of cases. Pain symptoms were the main indication for surgery in 70.1% of cases compared to 45.1% of cases in the comparison group. The structured approach used in the special endometriosis outpatient clinic is a key aspect of the care provided by the certified clinical and scientific endometriosis center. It ensures that patients are diagnosed and treated in accordance with guideline recommendations, that diagnosis and treatment comply with certification requirements, and that the collected data can be used to answer scientific questions.

Comparison of preoperative and postoperative sexual function in patients with deeply infiltrating endometriosis with and without bowel resection.

OBJECTIVE: To analyze preoperative and postoperative sexual function following surgery for deeply infiltrating endometriosis (DIE) with and without bowel involvement. STUDY DESIGN: Patients with DIE who underwent surgery between 2001 and 2011 with segmental bowel resection (WB) or without segmental bowel resection (WOB) were surveyed using the German version of the Massachusetts General Hospital Sexual Functioning Questionnaire (KFSP). Responses were given on a six-point scale for the items sexual interest, sexual arousal, orgasm, lubrication, and general sexual satisfaction. As there are no cut-off values for the existence of sexual function disorders, a control group with no history of endometriosis was evaluated. Differences between the preoperative and postoperative results, as well as between WB, WOB, and a control group, were compared using the Wilcoxon test, Mann-Whitney U test, and Fisher's exact test. RESULTS: Eighty-nine patients without bowel resection (mean age 34.3 years; mean follow-up 63.2 months), 87 patients with bowel resection (mean age 37.7 years; mean follow-up 69.6 months), and 100 control patients aged 21-58 years (mean age 35.0 years) were evaluated. Preoperatively, both treatment groups had significantly poorer scores in all categories in comparison with the control group. The WOB group improved significantly in all categories postoperatively, with no further significant differences from the control group. No significant postoperative improvement was observed in the WB group, and the group had significantly poorer scores in comparison with the control group. The number of previous operations is associated with significantly poorer postoperative KFSP results. Sterility and age > 40 years are associated with significantly less improvement in the KFSP, although with lower initial values. CONCLUSIONS: Patients with DIE with or without bowel involvement have significantly impaired sexual function preoperatively. Complete resection of endometriosis in the WOB group was able to improve sexual function, as the women had sexual scores similar to those in the healthy control group postoperatively. Possible explanations for the lack of postoperative improvement of sexual function after segmental bowel resection include the type of surgery carried out, or injury to the affected nerves resulting from the endometriosis.

Retraction Note: Improving usability and pregnancy rates of a fertility monitor by an additional mobile application: results of a retrospective efficacy study of Daysy and DaysyView app.

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Major and minor complications after resection without bowel resection for deeply infiltrating endometriosis.

PURPOSE: To analyze major and minor complications following surgery for deeply infiltrating endometriosis including long-term impairment of intestinal, bladder, and sexual function. METHODS: Patients who had undergone resection for deeply infiltrating endometriosis without anterior rectal resection between 2001 and 2011 were included (n = 134). Clinical and surgical data, as well as minor and major complications, were recorded. A questionnaire was sent to the patients and to a healthy control group (n = 100). RESULTS: Major complications occurred in 3.7% and minor complications in 12.7% of the patients. Surgical revision was necessary in five cases. The questionnaire response rate was 66.4%, with a mean follow-up period of 75.6 months. Weak urinary flow was reported by 26.4% of the patients; a feeling of residual urine by 16.1%; constipation by 13.5%; more than one bowel movement/day by 16.9%; insufficient lubrication during intercourse by 30.3%. The findings for weak urinary flow, feeling of residual urine, and insufficient lubrication differed significantly from the control group. Subgroup analysis did not identify any statistical associations between questionnaire responses and dyspareunia or dysmenorrhea as reasons for surgery, or previous endometriosis surgery in the patient's history. CONCLUSIONS: The major and minor complication rates were consistent with or lower than the literature data. Few studies have investigated complication rates associated with treatment for endometriosis in the sacrouterine ligaments and/or the rectovaginal septum. The high rates of impaired bladder function and sexual function after endometriosis surgery, as well as inadequate data, make further prospective studies on this topic necessary.

Improving usability and pregnancy rates of a fertility monitor by an additional mobile application: results of a retrospective efficacy study of Daysy and DaysyView app.

BACKGROUND: Daysy is a fertility monitor that uses the fertility awareness method by tracking and analyzing the individual menstrual cycle. In addition, Daysy can be connected to the application DaysyView to transfer stored personal data from Daysy to a smartphone or tablet (IOS, Android). This combination is interesting because as it is shown in various studies, the use of apps is increasing patients´ focus on their disease or their health behavior. The aim of this study was to investigate if by the additional use of an App and thereby improved usability of the medical device, it is possible to enhance the typical-use related as well as the method-related pregnancy rates. RESULT: In the resultant group of 125 women (2076 cycles in total), 2 women indicated that they had been unintentionally pregnant during the use of the device, giving a typical-use related Pearl-Index of 1.3. Counting only the pregnancies which occurred as a result of unprotected intercourse during the infertile (green) phase, we found 1 pregnancy, giving a method-related Pearl-Index of 0.6. Calculating the pregnancy rate resulting from continuous use and unprotected intercourse exclusively on green days, gives a perfect-use Pearl-Index of 0.8. CONCLUSION: It seems that combining a specific biosensor-embedded device (Daysy), which gives the method a very high repeatable accuracy, and a mobile application (DaysyView) which leads to higher user engagement, results in higher overall usability of the method.

Fumarate hydratase (FH) deficiency in uterine leiomyomas: recognition by histological features versus blind immunoscreening.

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome is a rare autosomal dominant disease caused by germline mutations in the fumarate hydratase (FH) gene. Affected individuals develop cutaneous and uterine leiomyomas and aggressive RCC. To date, only few publications described the frequency and morphology of FH-deficient uterine leiomyomas. We reviewed 22 cases collected over 8 years from routine and consultation files based on distinctive histological features. In addition, we screened 580 consecutive uterine leiomyomas from 484 patients, 23 extra-uterine and 8 uterine leiomyosarcomas, and 6 leiomyomas with bizarre nuclei for FH loss using immunohistochemistry (IHC) on tissue microarrays (TMAs). All 22 FH-deficient cases were suspected on H&E sections and confirmed by FH IHC. Patients' ages ranged from 25 to 70 years (median 36). Seventeen patients had multiple nodules (2-14) measuring up to 11.8 cm. None of the patients had stigmata or family history of the HLRCC syndrome. Histologically, all FH-deficient tumors showed consistent and reproducible features as reported previously. FH loss was detected in 2/534 evaluable leiomyomas (0.4%), but in none of leiomyosarcomas. Two of six leiomyomas with bizarre nuclei were FH-deficient. FH-deficient uterine leiomyomas are rare in routine material (= 0.4%). They can be reliably identified or suspected by consistent morphological features. Our data showed predictive morphology to be superior to blind IHC screening for detecting them. The relationship of FH-deficient uterine smooth muscle tumors to the HLRCC syndrome needs further clarification.

Major and minor complications after anterior rectal resection for deeply infiltrating endometriosis.

PURPOSE: The aim of the present study was to analyze major and minor complications-including long-term impairment of intestinal, bladder, and sexual function-following surgery for deeply infiltrating endometriosis using anterior rectal resection. METHODS: Patients who had undergone anterior rectal resection due to endometriosis between 2001 and 2011 were included (n = 113). Clinical and surgical data, as well as minor and major complications, were recorded. A questionnaire was sent to the patients and also to a healthy control group (n = 100). RESULTS: Major complications occurred in 15.9% of cases and minor complications in 15%. Patients with postoperative ileostomies (n = 8) initially had ultralow anastomoses significantly more often. The questionnaire response rate was 77%, with a mean follow-up period of 85.9 months. Weak urinary flow was reported by 22.4% of the patients: a feeling of residual urine by 18.4%; more than one bowel movement/day by 57.5%; and insufficient lubrication during intercourse by 36.5%. These results differed significantly from the control group. Subgroup analysis showed no statistical associations between questionnaire responses and major or minor complications, ultralow anastomoses, bilateral dissection of the sacrouterine ligaments, or dissection of the vagina and rectovaginal space. CONCLUSIONS: The major complication rate was consistent with the literature, but there were fewer minor complications. Patients with bowel anastomoses below 6 cm (ultralow) should receive information postoperatively about the high risk of insufficiency and should be closely monitored. The high rate of bladder, bowel, and sexual function impairment, and inadequate data make further prospective studies on this topic necessary.

Genetic risk factors for ovarian cancer and their role for endometriosis risk.

OBJECTIVE: Several genetic variants have been validated as risk factors for ovarian cancer. Endometriosis has also been described as a risk factor for ovarian cancer. Identifying genetic risk factors that are common to the two diseases might help improve our understanding of the molecular pathogenesis potentially linking the two conditions. METHODS: In a hospital-based case-control analysis, 12 single nucleotide polymorphisms (SNPs), validated by the Ovarian Cancer Association Consortium (OCAC) and the Collaborative Oncological Gene-environment Study (COGS) project, were genotyped using TaqMan® OpenArray™ analysis. The cases consisted of patients with endometriosis, and the controls were healthy individuals without endometriosis. A total of 385 cases and 484 controls were analyzed. Odds ratios and P values were obtained using simple logistic regression models, as well as from multiple logistic regression models with adjustment for clinical predictors. RESULTS: rs11651755 in HNF1B was found to be associated with endometriosis in this case-control study. The OR was 0.66 (95% CI, 0.51 to 0.84) and the P value after correction for multiple testing was 0.01. None of the other genotypes was associated with a risk for endometriosis. CONCLUSIONS: As rs11651755 in HNF1B modified both the ovarian cancer risk and also the risk for endometriosis, HNF1B may be causally involved in the pathogenetic pathway leading from endometriosis to ovarian cancer.

Association of vitamin D levels and risk of ovarian cancer: a Mendelian randomization study.

BACKGROUND: In vitro and observational epidemiological studies suggest that vitamin D may play a role in cancer prevention. However, the relationship between vitamin D and ovarian cancer is uncertain, with observational studies generating conflicting findings. A potential limitation of observational studies is inadequate control of confounding. To overcome this problem, we used Mendelian randomization (MR) to evaluate the association between single nucleotide polymorphisms (SNPs) associated with circulating 25-hydroxyvitamin D [25(OH)D] concentration and risk of ovarian cancer. METHODS: We employed SNPs with well-established associations with 25(OH)D concentration as instrumental variables for MR: rs7944926 (DHCR7), rs12794714 (CYP2R1) and rs2282679 (GC). We included 31 719 women of European ancestry (10 065 cases, 21 654 controls) from the Ovarian Cancer Association Consortium, who were genotyped using customized Illumina Infinium iSelect (iCOGS) arrays. A two-sample (summary data) MR approach was used and analyses were performed separately for all ovarian cancer (10 065 cases) and for high-grade serous ovarian cancer (4121 cases). RESULTS: The odds ratio for epithelial ovarian cancer risk (10 065 cases) estimated by combining the individual SNP associations using inverse variance weighting was 1.27 (95% confidence interval: 1.06 to 1.51) per 20 nmol/L decrease in 25(OH)D concentration. The estimated odds ratio for high-grade serous epithelial ovarian cancer (4121 cases) was 1.54 (1.19, 2.01). CONCLUSIONS: Genetically lowered 25-hydroxyvitamin D concentrations were associated with higher ovarian cancer susceptibility in Europeans. These findings suggest that increasing plasma vitamin D levels may reduce risk of ovarian cancer.