The Skin Cancer Burden From Occupational Sun Exposure In Canada

Cheryl PETERS, Carleton University, Canada

1 Department of Health Sciences, Carleton University, Ottawa, Canada
2 CAREX Canada, Simon Fraser University, Vancouver, Canada
3 Occupational Cancer Research Centre, Cancer Care Ontario, Toronto, Canada
4 Dalla Lana School of Public Health, University of Toronto, Toronto, Canada

Purpose
Ultraviolet radiation (UVR) is a known human carcinogen and people who work outdoors are at particular risk of non-melanoma skin cancer (NMSC) due to sun exposure.  This study estimated the attributable fraction (AF) of NMSC due to occupational sun exposure as part of a larger project to estimate the current burden of occupational cancers in Canada.
Methods
In order to calculate the AF, estimates of the proportion of workers ever exposed (PrE) during the risk exposure period (REP, 1961 – 2000), and relative risks (RR) for each of basal and squamous cell carcinomas (BCC, SCC) are required. To estimate the PrE, industry- and occupation-specific CAREX Canada estimates of prevalence and level of exposure were combined with historical Canadian employment data, labour force characteristics, and survival probabilities. RRs for BCC (RR=1.43) and SCC (RR=1.77) from recent meta-analyses were assigned to those in the moderate and high exposure groups, with the low exposed group considered not at risk for occupational NMSC.
Results
Approximately 2.6 million workers were ever exposed to solar UVR during the REP; 69% were in the high exposure group. The AF for NMSC was 10.4% for males, 1.3% for females, and 6.3% overall, which equated to a total of 4556 incident NMSC cases in 2011. Regarding the subtypes, 2846 BCC cases (AF = 5.3%) and 1710 SCC cases (AF = 9.2%) were attributable to outdoor work. Agriculture and construction made up the majority of cases by industry (51%).
Conclusions
Our study showed that a substantial burden of NMSC diagnoses in Canada may be attributed to working outdoors. We benefited from a more detailed exposure assessment than has been used in previous studies, but were challenged by the poorer quality of registry data for NMSC compared to other cancer sites.
Funding sources
Canadian Partnership Against Cancer, Canadian Cancer Society