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With the droughts and record temperatures throughout the U.S., many of our patients are wisely staying in the air conditioned indoors. Yet invariably, we will find ourselves dispensing advice on the use of sunscreens to prevent the development of skin cancer. But before we do, it may be important to remind ourselves of the controversial link between solar ultraviolet (UV) exposure and melanoma, and the utility of sunscreen to protect against its development.
The evidence is overwhelming that UV radiation is a risk factor for melanoma. UV-B causes the most DNA damage and may be more closely associated with melanoma than UV-A. Sun protection factor (SPF) measures the protection against UVB. SPF refers to the ratio of the minimal dose of solar radiation producing perceptible erythema (minimal erythema dose, MED) on sunscreen-protected skin and the MED for unprotected skin. New FDA regulations slated to take effect last month allow sunscreens to be labeled “broad spectrum” if they protect against both UVA and UVB. Products may only be called a “sunscreen” if they decrease the risk of cancer and premature skin aging.
The effectiveness of sunscreen for the prevention of melanoma has been controversial. The United States Preventive Services Task Force noted only limited evidence suggesting that sunscreen decreases melanoma incidence (Ann. Intern. Med. 2011;154:190-201).
However, a randomized trial involving more than 1,600 patients, aged 25 to 75 years, conducted in Queensland, Australia, suggested that sunscreen is very effective for reducing melanoma incidence. In this study, subjects were randomized to daily sunscreen (SPF 15+) use to head and arms over a 5-year period combined with 30 mg beta carotene or discretionary sunscreen application plus placebo supplements. After 10 years, 11 primary melanomas were diagnosed in the daily sunscreen group while 22 were diagnosed in the discretionary group (hazard ratio [HR], 0.50; 95% CI, 0.24 to 1.02; P = .051). A substantial reduction in invasive melanomas also was observed (3 active vs. 11 control; HR, 0.27; 95% CI, 0.08 to 0.97) (JCO 2011;29:257-63).
Only sun avoidance affords the best protection against melanoma. But for many of our patients this is not realistic. The best “skin tips” include: 1) use at least an SPF 15 (additional UVB protection above this rating is minimal); 2) apply at least a shot-glass full of sunscreen to cover exposed areas; and 3) re-apply sunscreen if out for several hours or if in contact with water.
Jon O. Ebbert, M.D. is a professor of medicine and a primary care clinician at the Mayo Clinic in Rochester, Minn. He declares having no conflict of interest. The opinions expressed are solely those of the author. Contact him at ebbert.jon@mayo.edu.
With the droughts and record temperatures throughout the U.S., many of our patients are wisely staying in the air conditioned indoors. Yet invariably, we will find ourselves dispensing advice on the use of sunscreens to prevent the development of skin cancer. But before we do, it may be important to remind ourselves of the controversial link between solar ultraviolet (UV) exposure and melanoma, and the utility of sunscreen to protect against its development.
The evidence is overwhelming that UV radiation is a risk factor for melanoma. UV-B causes the most DNA damage and may be more closely associated with melanoma than UV-A. Sun protection factor (SPF) measures the protection against UVB. SPF refers to the ratio of the minimal dose of solar radiation producing perceptible erythema (minimal erythema dose, MED) on sunscreen-protected skin and the MED for unprotected skin. New FDA regulations slated to take effect last month allow sunscreens to be labeled “broad spectrum” if they protect against both UVA and UVB. Products may only be called a “sunscreen” if they decrease the risk of cancer and premature skin aging.
The effectiveness of sunscreen for the prevention of melanoma has been controversial. The United States Preventive Services Task Force noted only limited evidence suggesting that sunscreen decreases melanoma incidence (Ann. Intern. Med. 2011;154:190-201).
However, a randomized trial involving more than 1,600 patients, aged 25 to 75 years, conducted in Queensland, Australia, suggested that sunscreen is very effective for reducing melanoma incidence. In this study, subjects were randomized to daily sunscreen (SPF 15+) use to head and arms over a 5-year period combined with 30 mg beta carotene or discretionary sunscreen application plus placebo supplements. After 10 years, 11 primary melanomas were diagnosed in the daily sunscreen group while 22 were diagnosed in the discretionary group (hazard ratio [HR], 0.50; 95% CI, 0.24 to 1.02; P = .051). A substantial reduction in invasive melanomas also was observed (3 active vs. 11 control; HR, 0.27; 95% CI, 0.08 to 0.97) (JCO 2011;29:257-63).
Only sun avoidance affords the best protection against melanoma. But for many of our patients this is not realistic. The best “skin tips” include: 1) use at least an SPF 15 (additional UVB protection above this rating is minimal); 2) apply at least a shot-glass full of sunscreen to cover exposed areas; and 3) re-apply sunscreen if out for several hours or if in contact with water.
Jon O. Ebbert, M.D. is a professor of medicine and a primary care clinician at the Mayo Clinic in Rochester, Minn. He declares having no conflict of interest. The opinions expressed are solely those of the author. Contact him at ebbert.jon@mayo.edu.
With the droughts and record temperatures throughout the U.S., many of our patients are wisely staying in the air conditioned indoors. Yet invariably, we will find ourselves dispensing advice on the use of sunscreens to prevent the development of skin cancer. But before we do, it may be important to remind ourselves of the controversial link between solar ultraviolet (UV) exposure and melanoma, and the utility of sunscreen to protect against its development.
The evidence is overwhelming that UV radiation is a risk factor for melanoma. UV-B causes the most DNA damage and may be more closely associated with melanoma than UV-A. Sun protection factor (SPF) measures the protection against UVB. SPF refers to the ratio of the minimal dose of solar radiation producing perceptible erythema (minimal erythema dose, MED) on sunscreen-protected skin and the MED for unprotected skin. New FDA regulations slated to take effect last month allow sunscreens to be labeled “broad spectrum” if they protect against both UVA and UVB. Products may only be called a “sunscreen” if they decrease the risk of cancer and premature skin aging.
The effectiveness of sunscreen for the prevention of melanoma has been controversial. The United States Preventive Services Task Force noted only limited evidence suggesting that sunscreen decreases melanoma incidence (Ann. Intern. Med. 2011;154:190-201).
However, a randomized trial involving more than 1,600 patients, aged 25 to 75 years, conducted in Queensland, Australia, suggested that sunscreen is very effective for reducing melanoma incidence. In this study, subjects were randomized to daily sunscreen (SPF 15+) use to head and arms over a 5-year period combined with 30 mg beta carotene or discretionary sunscreen application plus placebo supplements. After 10 years, 11 primary melanomas were diagnosed in the daily sunscreen group while 22 were diagnosed in the discretionary group (hazard ratio [HR], 0.50; 95% CI, 0.24 to 1.02; P = .051). A substantial reduction in invasive melanomas also was observed (3 active vs. 11 control; HR, 0.27; 95% CI, 0.08 to 0.97) (JCO 2011;29:257-63).
Only sun avoidance affords the best protection against melanoma. But for many of our patients this is not realistic. The best “skin tips” include: 1) use at least an SPF 15 (additional UVB protection above this rating is minimal); 2) apply at least a shot-glass full of sunscreen to cover exposed areas; and 3) re-apply sunscreen if out for several hours or if in contact with water.
Jon O. Ebbert, M.D. is a professor of medicine and a primary care clinician at the Mayo Clinic in Rochester, Minn. He declares having no conflict of interest. The opinions expressed are solely those of the author. Contact him at ebbert.jon@mayo.edu.