CANCER IN YORKSHIRE 1989-93

ACTIVITIES OF THE REGISTRY  


Registration

The Yorkshire Cancer Registry (YCR) is a population-based Registry which was established in 1957. Its aim is to collect and analyse data on every new case of cancer occurring in residents of the former Yorkshire Health region. The YCR also collects data on non-residents who receive treatment in Yorkshire. These data are exchanged with other cancer registries and this enables a complete dataset of patient activity, relevant to providers as well as purchasers, to be held by YCR.

The YCR serves a population of 3.7 million which constitutes 7.2% of the total population of England and Wales and is contained within a geographical area of approximately 5,300 square miles. During the period covered by this report there have been changes to the District Health Authority boundaries within Yorkshire. Data are presented, therefore, for the 17 former Districts and the 7 newly created purchasing authorities as outlined on page 120 of this report.

Cancers reported to YCR are currently defined by the codes included in the neoplasm chapter of the 9th revision of the International Classification of Diseases (ICD-9, WHO 1975). The range of data collected for each cancer patient is extensive and exceeds that held on any single hospital information system. Highly trained Registry staff collect detailed information on the site, type, size and stage of the cancer, the treatment given during the initial treatment period, where given, and by whom. These data are collected on a cancer registration form (page 121) and are linked on the YCR database with other sources of information such as death certificates and screening details to give an extensive picture of the "events" in the life of the cancer patient.

Cancer registration is based on multiple data sources for the same case to ensure completeness and quality. These sources include hospital departments (especially pathology departments), hospices, breast screening services, general practitioners and death certificates. Following the initial notification of new cancer patients to the YCR, clinical information is abstracted from case notes by YCR staff who visit hospitals and clinics in the region. The advantage of the "active" data collection system is that data are abstracted by our own trained staff who are aware of the needs of the Registry and are dedicated to providing high-quality data.

Copies of death certificates are routinely received from the Office for National Statistics for all cases where cancer is a cause of death. When this information is the first notification of cancer, the YCR sends an enquiry to the hospital where the patient died, or to the GP when the patient did not die in hospital.

Primary registration is only carried out from death certificate where no other information can be obtained. When the cause of death is non-malignant, the YCR is notified by the National Health Service Central Register, where all registered cancer patients are flagged.

Figure 1: Cancer Registration in Yorkshire

Cancer Registration in Yorkshire

 


Data Processing & Quality Control

A good computer system is fundamental to cancer registration both for ensuring the quality and validity of the data entered on the database and for making the data easily accessible to users. The data presented in this report were entered onto the cancer database using software (C-CRIS 1) specifically developed for cancer registration purposes in Yorkshire. The system incorporates many validation checks developed in-house and also those provided by the Office for National Statistics (ONS, formerly OPCS) and the International Agency for Research on Cancer (IARC). This software is currently being further developed, and the new version, (C-Cris 2), which will hold patient-based rather than tumour-based data, will permit more detailed information to be stored and will ensure that the Registry is equipped to meet the demands over the next quinquennium. The new software will be introduced in April 1997. Currently, over 400,000 registrations are held on the database.

In addition to the extensive edit programs carried out by the computer, the continuous process of routine checking for validity and consistency is undertaken by the YCR Quality Assurance Manager. Such a process involves comparing data with the original source documents or case-notes or simply scanning an abstract. Any inconsistencies are then rectified.

 


Indicators of Data Quality

The integrity of the Cancer Registry database is dependent on the completeness of registration and the validity of the diagnosis of the cases which it holds. The new national core contract for cancer registration lays down standards for completeness, accuracy, and timeliness in the collection of the minimum dataset. These standards, all of which are currently achieved by YCR, will become more stringent over time.

Three indicators of quality have been included in the summary statistics tables for each of the key sites presented in this report:

  1. Death Certificate Only (DCO) Registrations.
    These are cases for which Registries have no clinical documentation and which form part of the quota of "unsuccessful" cases as far as completeness of collection is concerned. Such cases are included in incidence rates, but excluded from survival analysis. DCO registrations comprised less than 4% of all registrations during the study period. The proportion varied by cancer site.

  2. Mortality/Incidence Ratio
    The ratio between the number of incident cases registered and the number of deaths per site shows a substantial time/space stability; thus sudden oscillations in M/I ratios are generally the result of under- or over-registration. It is axiomatic that if the number of deaths from cancer exceeds the number registered, then registration is incomplete. The ratio of mortality to incidence bears a strong inverse association to survival so that for lung cancer, for example, the ratio will be close to 100%.

  3. Histological Confirmation
    The percentage of cases which have been verified histologically is a positive indicator of the validity of diagnosis. The higher the proportion of histological verification, the more confident one can be that a neoplasm existed and that it was primary rather than metastatic. The YCR has had full co-operation of all pathologists in the region since 1978. Copies of pathology reports are notified directly to the Registry as a matter of routine. The histological confirmation rate for all invasive cases over the period of this report was 81%.

 


Timeliness of Data

One of the disadvantages of a system of multiple source registration is the delay in receiving and collating data from these diverse sources. Further delays are inevitable while the rigorous validation procedures and quality control methods are implemented prior to dissemination of information. Because of the need for more timely data, YCR staff are striving to process notifications more efficiently and considerable improvements can be demonstrated. By the end of 1995, 88% of cases diagnosed during 1994 had been completely registered. It is anticipated that over 90% of cases diagnosed during 1995 will be completed by the end of 1996.

 


Information Service

The installation of a dedicated computer system within the Registry and the widening of the YCR's reputation as a provider of cancer information have led to a substantial increase in the number of requests for information. The demand has grown from 160 requests in 1992 to 470 in 1995. Requests for the first six months of 1996 indicate a further growth to 550 this year. Current demands are for data to monitor trends in cancer incidence, referral patterns, treatment and outcome. Indeed YCR information is seen as vital to the development of evidence based evaluations of patient care and to the management of cancer service reorganisation as outlined in the "Calman/Hine Report". Another increase in demand has come from Cancer Family Clinics and genetics research projects, accounting for over 25% of requests received in 1995.

Figure 2: Number of Requests Processed by Cancer Registry

Information Unit Requests  

In his introduction to this report, Professor Forman made reference to the Quickdata project, the product of which will permit rapid and detailed outputs to be produced from our data and which will be circulated to our users on diskette during 1997. Further information technology developments mean that YCR information will also be available at a site on the World Wide Web:

             http://www.yco.leeds.ac.uk

Since the production of our last quinquennial report in 1991, the YCR has produced three site-specific reports on lung, head and neck, and breast cancer. The special report series, which are listed at the beginning of this report, provide more detailed information than that which is contained within this report. Other reports in the series, on gastro-intestinal and gynaecological cancers, are currently being planned and should be available in 1997.

For information requests, or copies of our reports, please contact Mr. Andrew Smith, Information Unit Manager: Tel 0113 292 4416.

Lesley Rider
Manager, Yorkshire Cancer Registry

 


contents - foreword - introduction - executive summary - acknowlegements -
activities of the registry - key site analysis (graphics) - more graphics - statistical tables - statistical methods - population tables - registration form