It is the reference and consultation document for the staff of any Cancer Registry. It contains a detailed description of the work rules, the classifications used for the coding of the different items and the criteria adopted in the Registry for exceptional cases. It also includes appendices on aspects of interest, mainly data related to the sources of information (person responsible or contact person for each source, information provided, frequency of consultation/notification, etc.).
The manual must be reviewed periodically, updating its contents with the changes made in the Registry's working methods
How the data is collected?
Traditionally, a difference is established between active and passive collection, although in general both methods coexist:
- Active collection: it is the Registry staff who go to the different sources of information to obtain the data. From the documentation, in general the medical records are the base document, the necessary information is extracted so that the case can be registered.
- Passive collection or notification: the staff of each source completes the notification forms or computer files with the data and sends them to the Registry.
It is necessary to know, in each center, the sources of information and their procedures, in order to identify what data are useful to the Registry and where they are found, in order to design the corresponding information flow or system. There will be sources that will be crucial for the detection of cases and others that will only have to be consulted in certain circumstances. Similarly, not all of them will offer the same quality guarantees.
Only a periodic evaluation of the sources, inexcusable in the first years of operation, allows adjusting the resources of the Registry and modifying the flow of inquiries, in relation to those sources that, due to accumulated experience, guarantee sufficient exhaustiveness and quality for the collection of information, avoiding an investment of resources in redundant sources, of low quality or in which it is not necessary to make a systematic but occasional consultation to solve the problem cases.
The work of the Registries is complex, it requires a continuous work of data collection and processing, of the evaluation of the activity and of the information sources, whose contribution may change with the passage of time. The inaccessibility of information sources and the deficit in the quality of the clinical documentation from different centers are problems that can clearly affect the proper functioning of the Registries.
Alluding to all these difficulties, Feinstein in 1967, mentioned in one of his articles that a good Cancer Registry professional should have a series of skills , among which he highlighted those of carrying out a good detection, search and follow-up of cases, those of finding old histories and deciphering the information existing in them, and those of seducing doctors to collaborate with the registry. The importance of these skills mentioned by Feinstein is still in full force.
Cancer Registries need to go or receive information from various sources, public and private, to: a) identify possible cases, b) confirm that they are true registrable cases, under the criteria defined by the Registry itself, and c) collect more detailed data depending on the objectives of the Registry.
The selection of information sources should be done in such a way as to ensure the completeness and validity of the information. The procedure followed must make it possible to integrate the information of the same person from different sources and detect the cases already registered, distinguishing whether they are multiple primary tumors or duplicate cases.
The recorded information is divided into three large blocks
Personal identification: It is essential to have a clear identification of the patient in order to be able to contrast the data from different sources and thus avoid duplication, both in the registration of cases and in the follow-up. The information collected must include the name and surname, and also other information such as the date of birth. It is essential to include a personal identification number (DNI., Unique health history number, Social Security number) that, in case of doubt, facilitates this procedure.
Data on the disease: Which includes aspects related to the history of the disease, the anatomical location of the tumor and its morphological characteristics. Registries increasingly record the stage at which the tumor is diagnosed due to their great interest in the study of survival. The treatment carried out, although data of extraordinary interest, is not routinely collected in population cancer registries, given the difficulties involved in searching.
Sources of information: The origin of the data collected will be stated, which will allow a new consultation if necessary.
Basic and optional data
The information accumulated in a Registry will be the minimum necessary to meet the objectives set, therefore, the basic data will be those that allow determining the incidence of cancer in the population covered by the Registry. Optionally, depending on your resources, other data considered of interest may be collected.
Before starting its activity, a Register carefully analyzes: a) the usefulness of each of the items to be included, in relation to the objectives set; b) if that information exists in the documentation to which you have access, and c) the quality of that information. Therefore, when considering adding a new item of information, it is necessary to question its need and whether the resources available to the Registry make it possible.
In addition to the general objectives of the Registry, specific objectives can be set to analyze in greater depth certain aspects related, for example, with the stage of the disease at the time of diagnosis. In this case, the extended collection of information can be limited to a sample of patients defined by the location of the tumor (breast, lung ...), the histological type (melanoma, lymphoma ...) or personal characteristics (children, adults...).
The development achieved by population cancer registries and their extensive experience in comparing data between registries from different fields has led to the establishment of internationally accepted definitions. Among the organizations or institutions involved in this effort, the International Association of Cancer Registries (IACR), the European Network of Cancer Registries (ENCR) and the International Agency for Research on Cancer (IARC), a body of the World Health Organization based in Lyon that has played and plays an important role, as promoter and coordinator of these activities.
In general terms, the definitions of the different information items in the Registry and their coding must be compatible with that of other information systems at national or international level, which will facilitate comparability. However, there are also certain items that each Registry must define to ensure consistent treatment of the information.