The Zimbabwe National Cancer Registry employs internationally recognised cancer registration and surveillance practices developed by relevant organisations and watchdogs such as the International Association of Cancer Registries (IACR), the International Agency for Research on Cancer (IARC) and the African Cancer Registry Network (AFCRN). Reference materials developed by the various organisations are available for use at the ZNCR.
The ZNCR is a multiple source cancer registration and surveillance system that has been population-based for Harare, the capital city of Zimbabwe since its inception in 1985. After the achievement of adequate coverage of the target population in 1990, the ZNCR has since been rapidly moving towards becoming population-based for the whole country.
The ZNCR uses a combination of active and passive methods of case finding. In order to register cancer cases, ZNCR staff visit institutions within the health-care delivery system of Harare that are involved in the diagnosis and management of cancer patients.
The Bulawayo branch of the ZNCR located in the country’s second city which covers the southern part of the country employs similar methods.
Cancer notification forms are filled in for each patient. Information collected includes patient demographic data: names, date of birth/age, sex, race and usual residential address. Hospital and patient numbers, date of diagnosis, method of diagnosis, primary site, histological type, extent and stage of disease are also collected. Basic data on initial treatment and follow-up are also collected. HIV status is also recorded when it is available.
The abstract forms are matched manually and electronically with the records in the ZNCR database in order to prevent multiple registrations.
The abstract forms are coded according to the International Classification of Diseases for Oncology (ICD-O-3) and entered into the computer using the CanReg cancer registration software provided by the IARC.
Regular routine visits to the inpatient wards of the 3 government referral hospitals in Harare (Harare Central Hospital, Parirenyatwa Group of Hospitals and Chitungwiza Central Hospital) are made by ZNCR staff. Patient interviews are conducted in order to record patient demographics accurately. Oncology outpatient clinics and medical records departments are also visited regularly.
The three major private hospitals in Harare (St. Anne’s Hospital, Avenues Clinic and West End Hospital) are visited regularly to collect cancer registration forms that are filled in by hospital staff. Arrangements are underway for the Registry to collect data from other smaller private hospitals and clinics.
The National Public Health Laboratory (NPHL) is visited regularly to abstract manually histology reports of cancer patients.
The ZNCR staff periodically visit the private Lancet Clinical Laboratories to identify and abstract histology and cytology reports of cancer patients from the laboratory’s records. The CIMAS Medical Laboratory submits copies of histology reports of cancer patients to the Registry on a monthly basis. The Bulawayo based Diagnostic Pathology Centre (DPC) periodically submits electronic copies of its histology database to the ZNCR.
Permission has been granted by the Premier Services Clinical Laboratories for ZNCR staff to have access to laboratory’s electronic histology and cytology databases to identify cancer diagnosis.
Patients managed at the Radiotherapy Centre (RTC) located at Parirenyatwa Group of Hospitals are registered through the Centre’s medical records system. ZNCR staff also visit the Centre during clinic days to interview and register patients.
The Bulawayo Registry is fully functional and continues to contribute data to the ZNCR. The main sources of information of the registry are: Mpilo Central Hospital, United Bulawayo Hospital (UBH), Mater Dei Hospital, the Radiotherapy Centre, Diagnostic Pathology Laboratory (DPC) and the Bulawayo death registry.
Patient records at Island Hospice and Healthcare were scrutinised to identify cancer diagnoses and abstracted. This is the first time that records of Island Hospice have been utilised. Records at the Hospice provided very useful follow-up information.
Incoming death certificate abstracts are matched with records in the ZNCR computer database. Information on the abstracts is used to update records of known patients.
For cases that were missed or not recorded but where the patients died in a medical institution, a ‘follow back’ is conducted. This involves the tracing of the patient’s records from the institution at which the patient died. A new registration is made when it is established that cancer was diagnosed.
These are referred to as death certificate notifications (DCNs) since death certificates were the first source of notification. When a follow back attempt is fruitless this leads to a death certificate only (DCO) registration. In this case the death certificate is the only document available for the registration. Due to inaccuracy of death certification in some cases, DCO registrations are made after thorough vetting and consultations.
The incidence of non-melanoma skin cancer (basal cell and squamous cell carcinomas) is quite high in the white and albino population of Zimbabwe.
This is typical of white populations of European descent living in sunny climates at low latitudes. Many patients will develop several lesions of the same histological type during their lifetime. The ZNCR only records the first lesion if the histology is the same. Subsequent lesions of the same histological type are ignored. However, basal cell carcinoma and squamous cell carcinoma of the skin in the same patient affecting the same or different sites are registered separately and are regarded as multiple primary tumours.
The ZNCR has over the years developed its own methods of detecting and avoiding multiple registrations to complement the conventional methods. Both manual and electronic methods are in place to identify and eliminate duplicates that might have evaded the tight record linkage process.
This is essential in Africa where the use of names and other demographic data is not always consistent.
Clinical data are coded to the 3rd edition of the International Classification of Diseases for Oncology (ICD-O-3) and socio-demographic data are coded to a system developed by the ZNCR that takes into account practices developed by the government Statistical Agency (Zimstat) for national use. For data analysis purposes, data are converted to the 10th edition of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) to facilitate international comparison.
Coding by Ethnic Groups
We report data for the black population, meaning the population of indigenous African descent and the non-black population, which comprises Europeans, Asians and Coloureds (mixed racial ethnicity).
The CanReg4 cancer registration software developed by the IARC is used for data processing. It is a reliable system that currently adequately meets the data processing requirements of the ZNCR. The Registry will be migrating to the current version 5 of the software in January 2017.