Recent Rise in Melanoma, and Getting the Balance Right Between Sun Exposure and Vitamin D
Today, the Canadian Cancer Society published statistics showing that rates of melanoma, the deadliest form of skin cancer, are on the rise. There were around 76,000 cases of non-melanoma skin cancer reported, and 6,500 cases of melanoma. Skin cancer incidence is similar to the incidence of all other cancers combined, however while most cases of non-melanoma skin cancer can be treated successfully, melanoma has a poorer prognosis and accounts for most of the deaths from skin cancer. Since 2001, melanoma rates have increased 2.2% per year in men and 2.6% per year in women in Canada.
Melanoma and the two types of non-melanoma skin cancer (squamous cell carcinoma, and basal cell carcinoma) have differing risk factors. Some of these risk factors are considered “non-modifiable” and include family history, skin type, and the presence of skin nevi (moles). The risk factors that people have control over involve exposure to UV light. The recent rise in use of tanning beds increases the risk of all three types of cancer, and is said to be responsible for the steady increase in melanoma incidence found in the Canadian report. Total sun exposure and also sunburn are listed as risk factors for all three types. Intermittent sun exposure, such as we might experience when visiting a sunny vacation destination, increases risk of melanoma only.
It is clear that people who want to avoid skin cancer should avoid tanning studios and spending too much time in the sun. Unfortunately, the sun provides an important source of vitamin D (see review by Wacker and Holick). Avoiding the sun also increases risk of vitamin D, as it is difficult to meet vitamin D recommendations by food alone.
And here lies the balancing problem: does one avoid the sun to reduce risk of skin cancer, or expose the skin to the sun to reduce risk of vitamin D deficiency?
The answer may depend on genetics, environment and personal choice. People with other risk factors such as pale, freckly skin and red hair, family history of skin cancer, and many dark brown or black nevi on their skin may be best off avoiding the sun as much as possible, diligently wearing sunscreen and protecting the skin when outdoors. A vitamin D supplement is a safe choice that ensures sufficiency. For other people without these characteristics, some experts such as Wacker and Holick recommend “sensible sun exposure”, if practical or desired. Indoor tanning is not recommended: the US Food and Drug Administration, World Health Organisation, and the European Commission all advise against it.
The Canadian Cancer Society, the Public Health Agency of Canada, Statistics Canada and provincial and territorial cancer registries. Melanoma: deadliest type of skin cancer is on the rise. 28 May 2014. http://www.cancer.ca/en/about-us/for-media/media-releases/national/2014/2014-canadian-cancer-statistics/?region=on
Bataille V. Sun exposure, sunbeds and sunscreens and melanoma. What are the controversies? Curr Oncol Rep. 2013 Dec;15(6):526-32. doi: 10.1007/s11912-013-0342-4. http://www.ncbi.nlm.nih.gov/pubmed/24142142
Field S, Davies J, Bishop DT, Newton-Bishop JA. Vitamin D and melanoma. Dermatoendocrinol. 2013 Jan 1;5(1):121-129. http://www.ncbi.nlm.nih.gov/pubmed/24494045
Pludowski P, Grant WB, Bhattoa HP, Bayer M, Povoroznyuk V, Rudenka E, Ramanau H, Varbiro S, Rudenka A, Karczmarewicz E, Lorenc R, Czech-Kowalska J, Konstantynowicz J. Vitamin D Status in Central Europe. Int J Endocrinol. 2014;2014:589587. Epub 2014 Mar 26. http://www.ncbi.nlm.nih.gov/pubmed/24790600
Wacker M, Holick MF. Sunlight and Vitamin D: A global perspective for health. Dermatoendocrinol. 2013 Jan 1;5(1):51-108. http://www.ncbi.nlm.nih.gov/pubmed/24494042