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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 .