Scottish Cancer Registry
Background and history
The Scottish Cancer Registry (SCR) has been collecting information on cancer since 1958. Approximately 45,000 registrations are made annually in Scotland and the cancer registration database currently holds over 1,400,000 records going back to 1958.
The registry is responsible for the collection of information on all new cases of primary malignant neoplasms, carcinoma in situ (including grade III intra-epithelial neoplasia), neoplasms of uncertain behaviour and (since 1 January 2000) benign brain and spinal cord tumours arising in residents of Scotland.
Data quality is monitored using routine indicators, computer validation and ad hoc studies of data accuracy and completeness of ascertainment. Data assurance is also achieved through data exchange with specialist tumour registries such as those of the Scottish Melanoma Group and the UK National Register of Childhood Tumours. For further information on the quality assurance of Scottish Cancer Registry data, please see this note [25KB].
Historically, there were five semi-autonomous regional registries that pooled their data with the central Scottish Cancer Registry. Reorganisation took place in 1997 to form a single cancer registry, managed by ISD, and supported by a team of dedicated ISD staff located in hospitals throughout Scotland.
For patients diagnosed up to 31 December 1996 a limited data set was collected. For patients diagnosed from 1st January 1997 onwards, an extended data set, including information on stage, (for breast, colorectal and cervical cancer) and information on treatment is collected for all patients. Data on ethnicity was also included but is often not available and therefore has always been poorly recorded with over 50% of cases recorded as 'unknown' ethnicity. The data items collected were in line with the minimum data set at that time for cancer registries in England and Wales. To coincide with the extended data collection a new online computer system was developed called SOCRATES (Scottish Open Cancer Registration And Tumour Enumeration System).
The SOCRATES system receives mainly electronic notification of cancer from hospital systems, including discharges (SMR01 records), radiotherapy, oncology, haematology and pathology records, prospective audit datasets as well as deaths from the General Register Office for Scotland and paper records from private hospitals. There are approximately 800,000 source records processed annually by the SOCRATES system using a complex set of rules and linkage routines to create provisional records. These records are accessed online by the team of outposted staff who use them along with local hospital systems to complete a single registration.
A delay of six months is necessary as SMR06 (the database of SOCRATES) is not an episode-based system, but is an accrued record of information on a primary tumour including patient data, diagnostic information and subsequent treatments.
In June 2006, following a period of redevelopment, a new, web based SOCRATES was launched. In addition to updating the technology, the new system features include: improved navigation and presentation of information, enhanced validation, new fields to collect pathological staging for breast and lung, clinical staging for lung and FIGO staging for ovary. From 2009 further hormone status data are being collected for breast. The new system functionality maximises the use of national reference files to derive geographical variables that are required for analysis (for example council area and parliamentary constituency). The data processing system has been further enhanced to improve record linkage and extend the range of source data including full pathology text and screening data.
Coding of cancer registrations
Cancer Information Officers code cancer registrations using the International Statistical Classification of Diseases and Related Health Problems (ICD), and the International Classification of Diseases for Oncology (ICD-O), as is done for all cancer registries. The timing of use by the SCR of the updated versions of ICD and ICD-O for incidence cases registered is as follows:
- Up to 31/12/1996: ICD-9 and ICD-O(1) morphology codes. Records prior to this date have been mapped to ICD-9 and ICD-O(1)
- 1/1/1997 to 31/12/2005: ICD-10, ICD-O(2) site and ICD-O(2) morphology codes
- From 1/1/2006 to present: ICD-10, ICD-O(2/3) site and ICD-O(3) morphology codes
Over time, the three main changes in classification and coding affect bladder tumours, ovarian tumours, and some haematopoietic neoplasms.
In line with recommendations of the European Network of Cancer Registries (ENCR) and subsequently the UK Association of Cancer Registries (UKACR), the SCR began coding non-invasive bladder carcinomas as neoplasms of uncertain behaviour or in situ carcinomas (depending on tumour grade). Prior to this, and in accordance with the index of the tenth revision of the International Classification of Diseases (ICD-10), the term 'bladder carcinoma' was coded as invasive disease (ICD-10 C67) unless otherwise specified. The change occurred around the year 2000. It led to an apparent decrease in the incidence of invasive bladder cancer, and a corresponding decrease in survival (due to the reclassification of better prognosis tumours as uncertain or in situ ). For this reason, bladder tumours of all behaviours are combined for the purposes of some analyses, especially for analysis of secular trends.
The second edition of the International Classification of Diseases for Oncology (ICD-O(2)), corresponding to ICD-10, recommended that cystadenomas of borderline behaviour of ovary, in the range M-8440-8490, should be coded as if invasive. ICD-10 and ICD-O(2) were adopted by the SCR for neoplasms incident from 1/1/1997 onwards. Prior to this, according to the first edition of the International Classification of Diseases for Oncology (ICD-O(1)), corresponding to ICD-9, they would have been coded as neoplasms of uncertain behaviour. With the introduction of the third edition of the International Classification of Diseases for Oncology (ICD-O(3)) (for neoplasms incident from 1/1/2006 onwards in Scotland), they reverted to neoplasms of uncertain behaviour, although coding according to ICD-10 remains unaltered.
The third edition of the International Classification of Diseases for Oncology (ICD-O(3)), adopted by the Scottish Cancer Registry for neoplasms incident from 1/1/2006 onwards, recommends coding myeloproliferative disorders and myelodysplastic syndromes as malignant. In the second edition of the International Classification of Diseases for Oncology (ICD-O(2)), corresponding to ICD-10, they were coded as neoplasms of uncertain behaviour. However, coding according to ICD-10 remains unaltered.
Using Registry Data
Cancer registry data are used for a wide variety of purposes which include public health surveillance; health needs assessment, planning and commissioning cancer services; evaluation of the impact of interventions on incidence and survival; clinical audit and health services research; epidemiolological studes; and providing information to support genetic councelling and health promotion. More detail on the contribution of cancer registries to improvement of cancer services is described on the website of the UK Association of Cancer Registries.