Cancer registration in Finland
Cancer registration in Finland started in 1952. In the 1950s, the reporting of cancers and certain benign
tumours was voluntary. In 1961 the National Board of Health issued a by-law making reporting
compulsory. All physicians, all hospitals and other institutions in the country must send a notification
to the Registry of all cancer cases that come to their attention. Pathological, cytological and
haematological laboratories send the respective laboratory notification. An increasing number of
notifications, especially from the pathological laboratories, but also from hospitals, are currently sent in
machine readable format. The automatic reporting contains the same information as the manual
reporting forms, including in the free texts detailed descriptions of the tumour site and histology.
In addition, Statistics Finland annually sends a computerised file on death certificates in which a
malignant disease is mentioned.
Both public and private institutions are very cooperative. The Finnish Cancer Registry and its staff are
highly recognised both among the scientific community and the health care sector in Finland. The
output of the Registry is widely used in research, administration, and health education on all levels.
All this improves the quality of the registration activity and is likely to contribute towards complete
coverage and high data accuracy in the Registry.
Primary medical care in Finland is provided to the entire population for nominal fees only. After initial
visits to a general or specialist practitioner, cancer patients are usually referred to hospital for
confirmation of the diagnosis and treatment. Patients are referred from one hospital to another
according to the needs for diagnostic examination and/or treatment.
Every patient with a diagnosis of cancer can be considered to be in a position to receive adequate
modern cancer treatment if such treatment is indicated. There are oncology units (with radiotherapy
facilities) in the five big university hospitals and four other (regional) hospitals. Cancer surgery is
practised in many general hospitals.
Everyone residing in Finland since 1967 has been assigned a unique 11-digit personal identifier (PID),
which is widely used in a number of different everyday events (including health care), and in all
important person registers. The PID of the patient is indicated on all cancer registry notifications, and it
is stored in the Registry database. It is the key in all practical registration procedures: e.g., in coding,
searching from the file, and combining notifications for one patient received at different times and from
different sources. For example, duplicate registration can thus be effectively avoided. PIDs have
greatly facilitated record linkage operations in Finland, and large and complicated computer runs can
be executed very rapidly and in a reliable way.
The following diseases are reported to the Registry:
- all malignant neoplasms, such as carcinomas (also basaliomas), sarcomas, malignant lymphomas,
leukaemias, multiple myeloma, gliomas, melanoma, etc.);
- carcinoid tumours, pheochromocytomas, thymomas, ameloblastomas, and chordomas;
- carcinoma in situ lesions (except those of the skin);
- CIN III and CIL III of the cervix uteri; histologically benign tumours of the central nervous system
and meninges, transitional cell papillomas of the urinary tract, and ovarian tumours with borderline
malignancy.
The Registry file is annually matched, through computerised record linkage (based on PIDs), with the
Cause of Death Register located at Statistics Finland, so that the dates and causes of death (also noncancerous causes, both underlying and contributory causes of death) can be added to the records in the
Registry.
The Registry file is also regularly linked with Central Population Register where the correctness of the
PIDs is checked, and the complete name, vital status, possible date of death or emigration as well as the
official place of residence prior to the date of diagnosis are obtained.
The cancer notifications submitted to the Finnish Cancer Registry are immediately stored to the
database at the Registry. Thorough visual and automatic checking procedures are carried out, both at
data entry and coding. The computer directly announces illegal codes and code combinations, as well
as illogical order of dates (of diagnosis, start of treatment, and death). Specific checks are carried out
when needed, e.g., completeness of the Registry has been evaluated in comparisons with the national
Hospital Discharge Registry [1].
If only laboratory and/or death certificate information is available, or if the data on the primary site of
the tumour or date of diagnosis are incomplete or controversial, requests for further information are
sent to the hospitals and physicians. This procedure is successful in a high proportion of the requests.
Final coding of cancer data is done by qualified secretaries and supervised by the Registry physician
(pathologist). The Registry has followed a slightly modified version of the ICD-7 nomenclature from
1955 for coding the primary site of cancer. However, during 2005 Finnish Cancer Registry will go over
to the ICD-O-3. For histology, the 2-digit codes of the American Cancer Society from 1951 are being
applied so far, slightly extended to meet the demands of the later decades. In the future the ICD-O-3
will also be followed for morphology. In practice it has been shown that it is not very important which
coding system is used: virtually any specific disease category can be formed on the basis of the existing
data. This also allows relatively precise conversion of old codes to ICD-O-3 back to the year 1953.
Each cancer considered to be an independent new primary lesion is registered separately. All
independent cancer processes are coded as separate entities. The Registry files contain about 950,000
cancer cases diagnosed in 1953-2004. In addition, there are a number of cases diagnosed prior to 1953
in persons who died from cancer or got a new primary cancer since 1 January 1953. More than 22,000
new cases of cancer are currently registered each year, plus some 4,500 basal cell carcinomas of the
skin and smaller amounts of some other lesions, which in the published statistics are usually excluded
from the total numbers of cancers [2].
The following coded items usually meet the needs of producing statistics and doing analytical research:
- name and PID,
- municipality of residence,
- primary site and date of diagnosis,
- basis of diagnosis,
- stage: localised, regional metastases, distant metastases,
- malignancy: malignant, microinvasive (cervix uteri), in situ, borderline (ovary), benign (intracranial,
urinary tract), or to be excluded from basic statistics (basalioma, polycythaemia vera, myelofibrosis,
etc.),
- histology/cell type,
- treatment: surgery, radiotherapy, cytotoxic drugs, hormones, other; specific codes for
curative/palliative surgery or radiotherapy; specific codes for primary treatment and later treatment,
- follow-up: date of death or emigration, cause of death.
All data received by the Registry on individual cancer patients remain in the computerised database. In
addition to the items listed above, for instance names of the notifying hospitals or laboratories,
specimen numbers, tumour grade, TNM classification, site of metastases, details of the treatment, or
cause for not being treated can, if needed, be used for different purposes, e.g., for searching the
histological slides for re-evaluation.
The Finnish Cancer Registry compares the official causes of death of each cancer patient (transferred
from Statistics Finland through an automatic record linkage procedure) to all data available for that
cancer, and evaluates whether the patient died from that cancer or something else. The cancer mortality
rates refined by the Cancer Registry allow the use of more detailed classifications of the cancer itself
than the official ones produced by Statistics Finland. Since the 1980s, the official rates have been very
close to the refined ones.
The Finnish Cancer Registry has emphasised the importance of data protection and personal privacy
years before it became an issue of debate in Western societies. No violations of the individuals' privacy
have occurred during the over 50 years of cancer registration in Finland. Data on the level of
individuals can be delivered to researchers working outside the Registry only through permission given
by the National Research and Development Centre for Welfare and Health (within the Ministry of
Healthand Welfare). Every year about 80 scientific papers are published based on the data and knowhow of the Finnish Cancer Registry [2].
The newest cancer statistics (incidence, mortality and prevalence) can always be found at the home
pages of the Finnish Cancer Registry (www.cancerregistry.fi).
References
[1] Teppo L, Pukkala E, Lehtonen M. Data quality and quality control of a population-based cancer
registry - experience in Finland. Acta Oncol 1994;33:365-9.
[2] Finnish Cancer Registry - Institute for Statistical and Epidemiological Cancer Research. Cancer
incidence in Finland 2000 and 2001. Cancer Statistics of the National Research and Development
Centre for Welfare and Health. Cancer Society of Finland Publication 65, Helsinki 2000.
The above text extracted from:
Pukkala E. Finland – cancer registration. In: Pukkala E, et al. Cancer atlas of Northern Europe. Cancer
Society of Finland Publication 62, Helsinki 2001, pp. 50-51.