Non-melanoma skin cancer, which includes squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), is the most common type of cancer in the United States and results in substantial morbidity and treatment costs. It is estimated that 1.2 million new cases of non-melanoma skin cancer occur each year in the United States. (BMC Dermatology 2001, 1:3).
Variations in the incidence of skin cancers between similar populations living at similar latitudes suggest other factors may play a role.
A Canadian study found elevated risks for squamous cell carcinomas in people exposed to insecticides, herbicides, fungicides and seed treatments as well petroleum products, grease, and several other exposures.
Elevated risks of basal cell carcinomas were seen in people exposed to fibreglass dust and dry cleaning. Also, prior non-diagnostic X-ray treatment for skin conditions increased risk of both cancers. (Cancer Epidemiol Biomarkers Prev 1996, 5:419-424).
Several studies have shown an association between cumulative ultraviolet exposure and risk of basal cell carcinoma, although the magnitude of risk conferred has been small.
Other studies have failed to find a significant association between estimated cumulative sun exposure in adulthood and the presence of basal cell carcinoma.
Other non-ultraviolet environmental exposures that have been associated with increased risk of basal cell carcinoma include ionising radiation, high dietary energy (especially fat), low intake of vitamins, and various chemicals and dust. Exposure to arsenic predisposes to multiple basal cell carcinomas. (BMJ. 2003 October 4; 327(7418): 794-798).
Among workers in direct contact with livestock, risk is apparently higher for squamous cell carcinomas. Although there is a slight possibility of false diagnoses of squamous cell carcinomas in the case of viral warts, such a problem would seem unlikely, in view of the fact that the cases were reviewed by a panel of pathologists who verified the diagnoses. (BMC Public Health 2007, 7:180doi:10.1186/1471-2458-7-180).
It has also been reported that 2% of such tumours could be associated with exposure to radon in the UK. (Health Phys 2003, 85:733-739).
The results of our study show a strong association between the occupation of miner and both types of non melanoma skin cancer, with the strength of association for basal cell carcinomas being double that for squamous cell carcinomas.
The explanation for this result might partly lie in the above-mentioned exposure to radon in the case of basal cell carcinomas; and possibly lie in exposure to arsenic in the case of squamous cell carcinomas.