Occupation and cancer - European Trade Union Institute (ETUI)

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between self-employed persons, family workers,
salaried employees, skilled workers, and unskilled
workers a total of 218 codes were possible. Entities
similar to those used in NYK were formed by
combining these occupational codes with the 245
codes for industry.
For the present study, the original national
occupation codes were converted to a common
classification with 53 relatively specific, but not too
small, occupational categories, and an additional
category of economically inactive persons (Appendix
1, available in the online version of the journal.
Please find this material with the direct link to the
article: http://www.informaworld.com/10.1080/0284
1860902913546). Descriptions of work included in
each of the categories are provided in Appendix 2.
The numbers of persons in the study by gender,
country and occupational category are shown in
Appendix 3.
Follow-up for cancer incidence
A person entered the cohort on January 1 of the year
after the first available census where s/he participated,
provided that s/he was 30-64 years old./he
participated, provided that s/he 30 64 years old.
Person-years were then counted until the date of
emigration, death or to December 31 of the following
years: in Denmark 2003, in Finland 2005, in
Iceland 2004, in Norway 2003, and in Sweden 2005
(Figure 11). The source of the data on dates of death
and emigration in all countries was the Central
Population Register. The numbers of person years
by gender, country and occupational category are
shown in Appendix 4.
The cancer registration in Denmark is based on
notifications from clinical hospital departments,
supplemented with notifications from practising
specialists in dermatology and gynaecology, and
with autopsy reports from pathology departments.
Throughout the period, the notifications were
supplemented with information on cancer cases
reported on death certificates. From 1988 onwards
linkage was also made with the Hospital Discharge
Register, and from 2002 onwards also with the
Pathology Register. In 1971 1977 the cancer cases
were coded according to an extended version of
the International Classification on Diseases, version
7, (ICD-7) [45], and from 1978 onwards according
to the International Classification on Diseases for
Oncology, version 1 (ICD-O-1) [46].
Cancer registration in Finland started in 1953
and the reporting has been compulsory since 1961.
Registration of new cases of cancer is based on
reports from clinical and pathological departments,
private clinics, general practitioners, and informa-
Occupation and cancer in Nordic countries 657
tion from the causes of death registry. The incident
cancer cases were coded for topography according to
the ICD-7 [45] and for morphology according to
MOTNAC 1951 [47], both nomenclatures extended
to correspond to the practical new needs of
classification.
In Iceland, cancer registration has from the start
(1955) been based on information from all pathology
laboratories in the country. This information
is complemented by information from cytology
and haematology laboratories, by notifications from
hospitals and health centres and by death certificates.
Topography was coded according to ICD-7
[45] and morphology according to ICD-O-1 [46].
Cancer registration in Norway has been based on
compulsory reporting of new cases of cancer from
clinical and pathological departments, private clinics,
general practitioners and information from the causes
of death registry since 1953. The pathology reports
provide histological, cytological or autopsy information.
Since 1998, the Patient Administrative Data
(PAD) system in hospitals has been used as an
additional source of information. Cancer cases diagnosed
before 1993 are coded according to ICD-7.
From 1993 ICD-O-2 has been used, with a semiautomatic
conversion back to ICD-7 codes, which
have been used in the classification of cancer in the
present study. MOTNAC was used for the coding of
morphology until 1993, but was then replaced by
ICD-O-2.
The cancer registration in Sweden in 1958 1982
was based on reports from hospital clinicians and
from hospital pathologists. Private practitioners have
been required to report cancer cases since 1983.
Notifications were collected and centrally coded in
Stockholm until 1984, when the coding was fully
decentralised to the six oncology centres (founded
during the period 1976 to 1984) The coding is done
simultaneously in several versions; 1958 until now in
ICD-7, 1987 until now in ICD-9, 1993 until now
ICD-O-2, and 2005 until now in ICD-O-3. The
histology has been coded with three digits according
to the statistical codes for human tumours by
the WHO from 1956 [48]. Unlike the other Nordic
countries, Sweden does not register cancer cases
based on death certificate only, and does not trace
back missing cases that could be identified via death
certificates.
Combined cancer incidence
The cancer cases have been grouped into 49 main
categories and 27 diagnostic sub groups based on
the national topography and morphology coding
systems (Appendix 5 and 6).