Wearing sunscreen to prevent skin cancer seems like a no-brainer. Unfortunately when I put my mind to it I found out this statement is more literal than I thought. It turns out that there is more epidemiological evidence that shows an INCREASE in skin cancer with regular sunscreen use.1 While there are some complexions, like those with freckles that may benefit from sunscreen use, the safe way to go seems to be using clothing, hats, and shade to reduce sun exposure without the risk of harmful chemicals.2,4,5 In a quantitative review of the literature from 1966-2003 Dennis, Freeman, & VanBeek found that “no association was seen between melanoma and sunscreen use.”6 The authors also note that the long-term effects of new sunscreens may take decades to determine.6 Green, et al. found “no significant differences in the incidence of first new skin cancers between groups randomly assigned daily sunscreen and no daily sunscreen” particularly not with basal-cell carcinoma.7 Routine sunscreen use for 4.5 years does show some effect for cutaneous squamous-cell carcinoma prevention.7
The Environmental Working Group just released an excellent sunscreen guide (updated link for 2011). After they reviewed 500 sunscreens they could only recommend 38 of them (in 2010). I highly recommend using those, or others that are comparable, especially since seemingly healthy ingredients like vitamin A have been recently shown to increase skin tumor growth and lesions.5 Just be sure that you do not increase your sun exposure because you are wearing sunscreen.
It is also very important to note that what state of health your body is in is more important than what you put on it, or how well you shield your self from the sun’s also beneficial rays.1,2,5 Eating a diet full of a wide variety of fresh fruits, vegetables, nuts and grains (that includes 7-9 servings of vegetables & fruits and plenty of properly preserved good fats) is an excellent way to start. Controlling stress through meditation, Qi Gong, Yoga, and exercise is also a very important component in preventing all types of cancer and disease. Cancer is a complex process that starts with an energy deficiency that gets the body’s complex dance of natural mechanisms out of balance, usually because of multiple compounding factors and including many external influences. Do what you can to reduce negative influences like stress, toxins and poor diet. Another 2011 update: Sulforaphane used topically is showing great promise for skin cancer prevention as an after sun exposure lotion (the only lotion I found with this so far has antifreeze in it also... be careful). You can also get sulforaphane in a pill. I am not sure if this can be used topically, but I am looking into it!
Responsible exposure to the sun is vital to our health! Most people are aware that vitamin D is needed for the absorption of calcium in the gut, but did you know that a deficiency can increase: muscle weakness, cancer, type 1 diabetes in children, congestive heart failure, hypertension, schizophrenia, depression, and wheezing?3 In fact, “93% of persons 10 to 65 years of age who were admitted to a hospital emergency department with muscle aches and bone pain and who had a wide variety of diagnoses, including fibromyalgia, chronic fatigue syndrome, and depression, were deficient in vitamin D.”3 To get enough D you need to expose your bare skin to sun that is unencumbered by buildings during the peak hours of the day. Holick (2007) recommends that “exposure of arms and legs for 5 to 30 minutes (depending on time of day, season, latitude, and skin pigmentation) between the hours of 10 a.m. and 3 p.m. twice a week is often adequate. “3
Methods: I searched Pub Med using the MeSH terms "Sunscreening Agents"[Mesh] AND "Skin Neoplasms"[Mesh] and limited the search to Clinical Trials, Meta-Analysis, Randomized Controlled Trials, in humans, in English, in the Core clinical journals. I received 16 results, a shockingly low number. However, considering the difficulty of time factors epidemiological data seems to be the best source of information as shown in the Meta-Analysis and quantitative review. All relevant articles were reviewed and represented in this article.
References:
1. Huncharek, M., & Kupelnick, B. (2002). Use of Topical Sunscreens and the Risk of Malignant Melanoma: A Meta-Analysis of 9067 Patients From 11 Case-Control Studies. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12084704
2. Gallagher, R., Rivers, J., Lee, T., Bajdik, C., McLean, D. & Coldman, A. (2000). Broad-spectrum sunscreen use and the development of new nevi in white children: A randomized controlled trial. JAMA 14;283(22), 2955-60. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10865273
3. Holick, M. (2007). The New England Journal of Medicine, 357, 266-81. Retrieved from http://www.vitamindhealth.org/?page_id=48
4. Glanz, K., Schoenfeld, E., & Steffen, A. (2010). A Randomized Trial of Tailored Skin Cancer Prevention Messages for Adults: Project SCAPE. American Journal of Public Health, 100(4), 745-741. Doi: 10.2105/AJPH.2008.155705
5. EWG’s Sunscreen Guide. In Environmental Working Group (ewg.org) Retrieved from http://www.ewg.org/2010sunscreen/?inlist=Y&utm_source=sunscreen&utm_medium=email&utm_content=first-link&utm_campaign=toxics
6. Dennis, L., Freeman, B., VanBeek, M. (2003). Sunscreen use and the risk for melanoma: a quantitative review. Ann Intern Med., 16:139(12), 966-78. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/14678916
7. Green, A., et al. (1999). Daily sunscreen application and beta-carotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomized controlled trial. Lancet 354(9180), 723-9. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10475183
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