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CLINICAL REPORT Advances in dermatology and venereology ActaDV Acta Dermato-Venereologica ActaDV
Shift in Occupational Risk for Basal Cell Carcinoma from Outdoor to Indoor Workers: A Large Population-based Case-control Register Study from Sweden
Bernt LINDELÖF 1, Jan LAPINS 1 and Henrik DAL 2
1
Department of Medicine, Dermatology and Venereology Unit, Karolinska University Hospital, and 2 Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
Basal cell carcinoma( BCC) is the most common form of cancer worldwide. Exposure of the skin to ultraviolet( UV) radiation, from sunlight and other sources, is the most important risk factor. The aim of this largescale case-control study was to determine which occupations are associated with increased risk of BCC in Sweden. The case cohort comprised 74,247 patients with BCC and the control cohort comprised 574,055 subjects linked to population-based registers. Compared with the occupational category of farmers, foresters and gardeners we observed elevated risks of BCC for almost all occupational categories studied. Legal workers with odds ratio( OR) 2.69( 95 % confidence interval( CI) 2.36 – 3.06), dentists OR 2.69( 95 % CI 2.35 – 3.08) and physicians OR 2.47( 95 % CI 2.24 – 2.74) had the highest risk for both sexes taken together. In conclusion, there appears to have been a change in the risk of BCC from outdoor to indoor occupations in Sweden, possibly related to exposure to UV radiation during leisure activities exceeding occupational sun exposure as the main cause of BCC in Sweden.
Key words: epidemiology; occupation; basal cell carcinoma. Accepted Mar 27, 2017; Epub ahead of print Mar 30, 2017 Acta Derm Venereol 2017; 97: 830 – 833.
Corr: Bernt Lindelöf, Department of Medicine, Unit of Dermatology and Venereology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden. E-mail: bernt. lindelof @ karolinska. se
Basal cell carcinoma( BCC) of the skin is the most common type of cancer worldwide( 1). Although BCC is a malignant tumour, it very rarely metastasizes and mortality is low. However, because of the number of cases, this places a huge burden on healthcare resources( 2). Exposure to ultraviolet( UV) radiation from sunlight remains the most important environmental risk factor( 3).
There are only a limited number of epidemiological studies of occupational cases of BCC( 4 – 8). This may be due to the fact that BCC cases, in spite of the high incidence, are rarely included in central cancer registries. Occupational skin cancer may also be under-reported( 9).
A systematic review of the literature regarding occupational exposure to UV and occurrence of BCC concluded that outdoor workers were at significantly increased risk for BCC( 10). Farmers are considered to be a group at high risk for BCC( 11), but studies related to farm workers, sun safety behaviour, and skin cancer are scarce( 12).
However, in recent times, the role of sun exposure in different occupations might have become of less relative importance than leisure time in the sun, taking into account the changing sun behaviour patterns of the general public along with the increasing travel to sunny resorts and use of artificial tanning sunbeds. Furthermore there are a number of other risk factors than sun exposure, e. g. ionizing radiation or chemical agents that might be relevant in certain occupations( 13).
Interestingly, in a large population-based study of occupation and cancer in the Nordic countries, fishermen and forestry workers were ranked as the groups with the lowest risk of malignant melanoma and non-melanoma skin cancer in men( BCC was not included)( 14). The aim of the present study was to evaluate the role of occupation in BCC. A large number of BCC patients and control patients from an earlier study were included( 15). The study used data from the public, population-based, and non-insurance-based Swedish healthcare system and population-based mandatory national cancer register. Subjects’ unique personal identification numbers allowed register linkage. The patients’ and controls’ demographics, socioeconomic status and place of residence were adjusted in order to obtain reliable data.
METHODS Ethics and study population
The study was approved by the Regional Ethics Review Board, Stockholm( 2009 / 55).
During the years 2004 to 2008 a total of 115,016 cases of BCC were reported to the Swedish Cancer Registry. For this study a case of cancer was considered to be a BCC for all topography codes between T01000 and T02830 with a histopathology code between M80903 and M80953( variants of BCC).
In the 17 % of the patients who had 2 or more BCC reported to the registry, the first verified BCC was included in the study. Incidence density sampling was applied to find 10 controls with the same age and sex with which to match the cases. The controls were identified from the Register of Total Population( 2004 – 2008). Incidence density sampling makes it possible for a case to be selected as a control before its own cancer is diagnosed. They were further required to be alive and free of BCC at the time of BCC diagnosis of the case. For each case and control, information was received from the databases of persons participating in doi: 10.2340 / 00015555-2660 Acta Derm Venereol 2017; 97: 830 – 833
This is an open access article under the CC BY-NC license. www. medicaljournals. se / acta Journal Compilation © 2017 Acta Dermato-Venereologica.