Today we know to protect children from excessive sun exposure, but most of us over the age of 50 have sunburns in our personal history. We can't go back and change the past. Ultraviolet light, from the sun or artificial light sources, is a risk factor for all three major types of skin cancer. Basal cell carcinoma is the most common, and originates in the deepest layers of the epidermis. Squamous cell carcinoma is also common, and originates in the middle layers. Melanoma is much less common, but much more dangerous, and originates in the cells that produce pigment.
Dr. Annette Ostergaard Jensen and colleagues at Aarhus University Hospital in Denmark performed a study of how basal cell carcinomas and squamous cell carcinomas affect overall health. These types rarely metastasize, and are not even included in the American Cancer Society's 2010 report of new cancer cases and deaths in the United States.
Melanoma is considered a much more serious disease. The American Cancer Society report estimated 68,130 new cases of melanoma and 8,700 deaths from it. For comparison, lung cancer deaths are higher by a factor of 18.
So how bad are the non-melanoma skin cancers? If you get one, are you at higher risk for other cancers or a shorter life expectancy? Jensen's report is reassuring. Her study included 72,295 patients with basal cell carcinoma, 11,601 with squamous cell carcinoma, and 383,714 demographically matched controls. The results showed that basal cell carcinoma is associated with a reduced mortality risk, while squamous cell carcinoma is associated with only a small increased mortality risk.
Jensen interpreted these results as follows. Ultraviolet light is the prime risk factor for basal cell carcinoma. Patients with this type of cancer were likely to have higher vitamin D levels throughout their lives. Earlier studies cited by Jensen show reduced mortality from cardiovascular disease, chronic pulmonary disease, and diabetes in individuals with adequate vitamin D. The situation for squamous cell carcinoma is more complicated. Risk factors for this type of cancer include:
1. Ultraviolet light exposure
2. Immunosuppressive drugs
3. Viral carcinogens in the skin
4. Chemical carcinogens
5. Ionizing radiation and phototherapy
6. Chronic diseases associated with a weakened immune system
Thus, Jensen concluded that squamous cell carcinoma is a marker for other illnesses, while basal cell carcinoma is a marker for good vitamin D levels. Her results are in agreement with the American Cancer Society's decision to omit these types from their statistical report. Non-melanoma skin cancer is certainly not desirable, but it's much less serious than other types of cancer.
References:
1. Jensen AO et al, “Non-melanoma skin cancer and ten-year all-cause mortality: A population-based cohort study”, Acta Derm Venereol 2010; 90: 362-67. http://www.ncbi.nlm.nih.gov/pubmed/20574600
2. PubMed Health information on skin cancer:
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002414/
3. American Cancer Society statistics:
http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/acspc-026238.pdf
Reviewed July 6, 2011
by Michele Blacksberg R.N.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.