Danish Gynecological Cancer Database

Aim of database

The aim of the Danish Gynecological Cancer Database (DGCD) is to achieve the greatest possible knowledge regarding examination, treatment methods, and results within the field of gynecological cancer in Denmark. The purpose is treatment quality assurance and improvement, and generation of scientific data.¹

Study population

DGCD is by definition nationwide: “a clinical quality registry where a minimum of 90% of the relevant patient population in Denmark is registered”.² The database was initiated on January 1, 2005. The database before June 1, 2013, is referred to as the old DGCD and the database after this date as the new DGCD. Data from the old DGCD are mapped into the new DGCD in order to assure continuity. Since July 2015, 19,729 patients had been registered in DGCD, on average 1,879 patients per year since January 1, 2005. Table 1 shows an overview of the patients currently enrolled in DGCD and the diagnoses that DGCD covers.^3,4 As seen in Table 2, DGCD has had a high coverage rate throughout the years. The coverage estimates are based on the registrations in the Danish National Patient Registry (NPR).

Table 1 The DGCD’s present patient population according to diagnosis Note: aDue to the mapping of data from the old DGCD to the new DGCD, the number of patients enrolled in 2005–2011 and the number of patients enrolled in 2011/2012 will have a small overlap. Abbreviation: DGCD, Danish Gynecological Cancer Database.

Table 2 Data coverage during the life span of the database based on data from the database Quality Management System (QMS) and the Danish National Patient Registry (NPR) Notes: aDue to increased scrutiny of the new database, there are fewer patients in the database from this period than previously reported. N/A: Data not available. Abbreviation: DGCD, Danish Gynecological Cancer Database.

Main variables

Data are registered online in special data forms programmed in the TietoEnator’s quality measurement system.⁵ Data are placed on a central server hosted by the Registry Support Center (East) – Center for Clinical Quality Improvement and Health Informatics.

The data of DGCD are primarily recorded in four main online forms: clinical data, surgery, pathology, and final quality check. In the old DGCD, some of the variables were optional, thus resulting in varying registration of the optional variables. In the new DGCD, optional data requirements have been eliminated. Due to the setup of the old DGCD, it was possible to add and fill in data forms in a way in which the sequence of patient events were incorrectly registered. In order to get valid data, constant data review and time consuming correction by doctors and secretaries was needed. The structure of the data forms in the new DGCD ensures correct registration.

The first data form covers clinical data. The data are registered by gynecologists specializing in gynecological oncology. The second data form covers surgical data recorded by surgeons specializing in gynecological oncology. The third data form covers pathology data that are registered by a pathologist. All data forms are designed to logically and consecutively provide variables specific for each type of gynecological cancer and surgery.

Staging follows the “International Federation of Gynecology and Obstetrics” (FIGO) system. Staging reports are available both in the FIGO and Tumor Nodes Metastasis system. In case of ovarian cancer, the final staging is based on both surgical and pathological staging. In uterine cancers, the pathological staging is determinative. When the diagnosis is based only on a biopsy, the gynecological clinician can choose to stage the disease based on imaging and clinical findings. The staging follows the FIGO guidelines. Staging and treatment of cervical, vulva, and ovarian cancer is centralized in Denmark and only allowed in centers with specialized gynecological oncologists.

The fourth data form is the final quality check, which is recorded by the gynecologists. Data from all data forms described earlier are consolidated and from this the final staging and diagnosis is performed.

In the new DGCD, data forms for registering pre- and postoperative nurses’ care and data forms for vulva/vaginal cancer and trophoblastic disease were added in 2013. An overview of the main variables in DGCD is presented in Table 3. The old DGCD also included a data form for registration of data regarding the oncological treatment. Due to poor cover rate, this data form was omitted in the new DGCD. Oncologic data in the new DGCD are imported from the NPR which only includes date and type of oncologic treatment.

Table 3 Main variables in DGCD – an overview Abbreviations: DGCD, Danish Gynecological Cancer Database; BMI, body mass index; WHO, World Health Organization; FIGO, International Federation of Gynecology and Obstetrics.

In addition, data such as diagnosis, duration of hospitalization, and perioperative complications are drawn from the NPR. In this way, DGCD data are both validated and supplemented. Pathological data regarding histology and relapse biopsies are drawn from the Danish Pathology Register, data regarding cause of death from the Cause of Death Register, and overall survival from the Civil Registration System, which is updated day-to-day.

Follow-up

Data regarding follow-up are registered in DGCD with a form describing each follow-up visit, including registration of relapse and residual disease. The unique nationwide Civil Registration System and Cause of Death Register ensure virtually complete follow-up of all patients recorded in the DGCD. Until recently, Danish gynecologic cancer patients had follow-up visits at the hospital for 5 years or to recurrence and/or death. According to new guidelines from the National Institute of Health, follow-up visits after the first year will now be based on need.

Examples of research

DGCD has formed the basis of several scientific studies and publications. This spans from scholarship fellows and bachelor theses to PhD theses, doctoral theses, and post-doc publications. In 2014 alone, DGCD data were used in nine ongoing PhD projects and three ongoing post-docs.⁶

Several DGCD studies have been published for assurance of quality. Fagö-Olsen et al demonstrated in 2011 that centralization of treatment for ovarian cancer improves survival. It was shown that patients with stage IIIC and IV ovarian cancer benefit from treatment in a tertiary referral center.⁷

Another quality study based solely on DGCD data by Håkansson et al in 2012 validated the use of the risk of malignancy index (RMI) as a tool for ovarian cancer risk assessment and referral to a tertiary center. They found that RMI ≥200 was a reliable tool for identifying patients with ovarian cancer.⁸

In 2014, Svolgaard et al published an article for assurance of quality based on DGCD data. The aim was to evaluate the Danish nationwide progress in implementing lymphadenectomy for women presenting with tumor(s) macroscopically confined to the ovary, and the effect of lymphadenectomy on the overall survival. The study concluded that the national number of lymphadenectomies was too low, although increasing, and that the effect of lymphadenectomies on overall survival was not significant.⁹ The results of the study formed the basis for a very intense debate about systematic lymphadenectomy and revision of guidelines. DGCD publishes annual reports, which are widely used as a source of quality results of Danish gynecologic cancer treatment.³

A DGCD validation study from 2014 concluded: the data on endometrial cancer registered in the DGCD regarding surgery and pathology is valid and complete, and they provide a solid base for research.¹⁰ The completeness of data on pathology and surgery reported to the DGCD was 97.3% and the agreement for the reported data in the DGCD was 88.3%.¹⁰

A DGCD validation study on postoperative complications in ovarian cancer, tubal cancer, and ovarian borderline tumor patients showed that the completeness of reporting to the DGCD was 94.2% and the strength of agreement between the variables in the DGCD and the medical file varied from moderate to very good.¹¹ A new large validation study on ovarian cancer based on a combination of NPR and DGCD variables is currently under progress (personal communication by Sørensen et al, March 6, 2016). DGCD has also been used in studies showing how comorbidity independently affects overall survival in women with uterine or ovarian cancer.¹²

DGCD is furthermore extensively used in translational and clinical national and international studies as data are easily combined with data from the Danish Cancer Biobank.^13–16 In one of the first DGCD-based translational studies from 2010 performed by Petri et al, data from DGCD combined with material from the Danish Cancer Biobank were used in comparison of proteomic biomarker panels in urine and serum for ovarian cancer diagnosis. The authors concluded that urine and serum proteomic panels can be used individually or in combination in ovarian cancer diagnostics.¹⁷

The Danish Multidisciplinary Cancer Group (DMCG) produced a report on cancer survival in Denmark in the period 1995–2012.¹⁸ This report included calculations of ovarian cancer survival based on DGCD data. The report showed that the 5-year survival for ovarian cancer was 37% in the period 2005–2009, that the mortality rates of ovarian cancer patients in Denmark have been decreasing since 1995, and the survival trends have been gradually increasing since 2000. This report provided important information on trends in the management and prognosis of ovarian cancer. Edwards et al have continued working on the report.¹⁹

Administrative issues and funding

The DGCD is funded by the Danish regions. The monitoring and improvement of the treatment quality of gynecological cancer is the key objective that ensures the funding of DGCD, which is anchored to the national expert group, the Danish Gynecological Cancer Group, consisting of clinicians and researchers responsible for developing and maintaining national clinical guidelines for the treatment of gynecological cancer. DGCD is under the auspices of the DMCG; an umbrella organization comprised of 24 national, disease-specific cancer groups and clinical databases. The running and maintenance of DGCD is managed by the DGCD steering committee, which consists of a chairperson and 14 members appointed by the Danish Gynecological Cancer Group board and the Registry Support Centre (East) – Centre for Clinical Quality Improvement and Health Informatics.

To ensure maximal coverage rate, shortage lists are created specifically for each hospital and continually updated. The steering committee develops the annual DGCD report and clinical quality indicators in cooperation with Registry Support Centre (East) – Epidemiology and Biostatistics. The present 13 quality indicators, which are used to monitor the quality of the management of gynecological cancer between different regions of Denmark and across hospitals, are presented in Table 4. The quality indicators are under constant validation and development.³

Table 4 Clinical quality indicators used Abbreviation: FIGO, International Federation of Gynecology and Obstetrics.

Conclusion

The DGCD is a large compulsory nationwide clinical database with a high coverage of all gynecological cancers. The large number of variables provides a basis for several quality and research publications. The selected data from all the registers are, together with DGCD data, available in a structured form in the Statistical Analysis Software portal and as raw data. This very complete collection of available data from several registers forms one of the unique strengths of DGCD, compared to many other clinical databases. It provides unique possibilities for validation and completeness of data. Other unique strengths of the DGCD are the high coverage, almost 100% follow-up, and that DGCD represents data from all Danish patients with a gynecologic malignancy with minimal risk of selection bias in research and presentations. One of the major problems in DGCD registration is the lack of specific oncology data such as more detailed oncologic treatment, oncologic complications, and response and relapse data

Acknowledgments

The large data source of DGCD relies on the entry of relevant data by the clinicians. We thank all of our colleagues from Denmark’s gynecological, pathology, and oncological wards for their thorough work. Data in the DGCD are collected in accordance with current Danish data protection laws. The Data Protection Agency and the National Board of Health govern the laws and procedures for data access to DGCD. This paper was funded by the Program for Clinical Research Infrastructure (PROCRIN) established by the Lundbeck Foundation and the Novo Nordisk Foundation and administered by the Danish Regions.

Disclosure

The authors report no conflicts of interest in this work.

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References

1.	DGCG Executive Committee. DGCD Regulations, October 2, 2013. §6.2.
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3.	Danish Gynecological Cancer Database. National report 2014/2015. Available from: http://www.dgcg.dk/images/rsrapport_DGCD_2014-15.pdf. Accessed February 6, 2016.
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