“Don’t become the one out of seven who will be affected this year.”
As we head into the summer months, our thoughts turn to fun in the sun. But all that fun may come at a price in our future. Sun exposure is linked to the development of skin cancer, which can be cured, but can also be deadly. In this month’s post, we review the important facts on skin cancer, and what we can do to prevent it.
Your skin’s important role
Your skin protects you against heat, light, injury, and infection. It’s your first line of defense between an often-hostile external environment and the sensitive tissues and organs inside your body. Your skin regulates body temperature and stores water, fat, and vitamin D. It is a complex organ, and by virtue of it’s surface area, is your largest organ.
Your skin is made up of two main layers, the epidermis (the outer layer of skin) and the dermis (the inner layer of skin). The epidermis contains three kinds of cells: flat, scaly cells on the surface called squamous cells; round cells called basal cells; and cells called melanocytes, which give your skin its color. Skin cancer is a disease in which cancer (malignant) cells are found in one type of the cells of the outer layer of your skin.
How to recognize skin cancer and who’s most at risk
Skin cancer is the uncontrollable growth of abnormal cells in a layer of the skin. Unfortunately, about one out of every seven Americans are afflicted each year, making it the most prevalent form of cancer. However, ninety percent of all skin cancers can be cured if detected and treated in time. According to some estimates, Americans who live to the age of 65 have a risk up to 50 percent of developing skin cancer at least once. Although anyone can get skin cancer, those most at risk are people (1) with a high number of moles, (2) with red or fair hair, blue eyes, fair skin and freckles, (3) who tan with difficulty and burn in the sun, and (4) with a history of the disease in two or more family members.
Skin cancer can look many different ways. The most common sign of skin cancer is a change on the skin, such as a growth or a sore that won’t heal. Sometime there may be a small lump. This lump can be smooth, shiny and waxy looking, or it can be red or reddish brown. Skin cancer may also appear as a flat red spot that is rough or scaly. You should see your doctor if you notice changes in your skin.
Some skin lesions are not cancers. Two other common types of skin growths are moles and keratoses. Moles are clusters of heavily pigmented skin cells, either flat or raised above the skin surface. While most are completely benign, some very large moles present at birth, or those moles with mottled colors and poorly defined borders, may develop into malignant melanoma. Moles are often constantly irritated by clothing or jewelry, which can sometimes cause pre-cancerous changes. For this, or for cosmetic reasons, they are frequently removed.
Solar or actinic keratoses are rough, red or brown, scaly patches on the skin. They are usually found on areas exposed to the sun, and sometimes develop into squamous cell cancer.
The major types and the warning signs
There are three major types of skin cancers, distinguished by the types of cells affected. These are basal cell carcinoma, squamous cell carcinoma and malignant melanoma. Of these three, basal cell is the most easily cured, and melanoma is the most difficult to cure and the most likely to spread (metastasize).
There are some warning signs for skin lesions that suggest they may be a malignant melanoma. These warning signs are called the “ABCD” warning signs of melanoma: Asymmetry-a growth with unmatched halves; Border irregularity-ragged or blurred edges; Color-a mottled appearance, with shades of tan, brown, and black, sometimes mixed with red, white, or blue; and Diameter– a growth more than 6 millimeters across (about the size of a pencil eraser), or any unusual increase in size.
The major message here is to get to know your skin, and be observant for changes. Most will not be cancerous, but you need to know what to look for in order to determine which lesions are at risk.
So what causes Skin Cancer?
There are three major factors that determine your risk of skin cancer:
- Sunburn and UV light can damage your skin, and this damage can lead to skin cancer. Notice we didn’t say sunlight; UV light from tanning lamps are also a risk factor. However, both the total amount of sun you have received over the years, and overexposure resulting in sunburn can cause skin cancer. Most people receive 80% of their lifetime exposure to the sun by 18 years of age. The message to parents from this is to protect your children. Skin cancer is related to a lifetime exposure to UV radiation. Although skin cancer usually appears after age 50, the sun’s most damaging affect begins at an early age.Tanning is your skin’s response to UV light. It is a protective reaction to prevent further injury to your skin from the sun. However, it does not prevent skin cancer. Remember, skin cancer is very slow to develop. The sunburn you receive this week may take 20 years or more to become skin cancer.
- Heredity plays an important role in the development of skin cancer. If there is a history of skin cancer in your family, you are probably at a higher risk. People with fair skin and with a northern European heritage appear to be most susceptible.
- Environment in which you live is also a consideration. The level of UV light today is higher than it was 50 or 100 years ago. This is due to a reduction of ozone in the earth’s atmosphere (the Ozone Hole). Ozone serves as a filter to screen out and reduce the amount of UV light that we are exposed to. With less atmospheric ozone, a higher level of UV light reaches the earth’s surface. Other influencing factors include elevation, latitude, and cloud cover. Ultra Violet light is stronger as elevation increases. The thinner atmosphere at higher altitudes cannot filter UV as effectively as it can at sea level.
One factor that actually reduces UV exposure is cloud cover. Climates and with regular cloud cover may have a 50% lower level of UV light. The actual amount is affected by the density of the clouds.
Steps that you should take to prevent skin cancer
A great football coach once said that the best offense is a good defense. This is very true for skin cancer. Skin cancer can be prevented if all suspicious lesions were brought to the attention of doctors before they had a chance to spread. People should regularly check their skin for new growths or any other changes. Any changes should be reported to a doctor immediately!
The following six steps have been recommended by the American Academy of Dermatology and the Skin Cancer Foundation to help reduce the risk of sunburn and skin cancer.
- Minimize your exposure to the sun at midday and between the hours of 10:00AM and 3:00PM.
- Apply sunscreen with at least a SPF-15 or higher, to all areas of the body which are exposed to the sun.
- Reapply sunscreen every two hours, even on cloudy days. Reapply after swimming or perspiring.
- Wear clothing that covers your body and shades your face. (Hats should provide shade for both the face and back of the neck.)
- Avoid exposure to UV radiation from sunlamps or tanning parlors.
- Protect your children. Keep them from excessive sun exposure when the sun is strongest (10:00AM and 3:00PM), and apply sunscreen liberally and frequently to children 6 months of age and older. Do not use sunscreen on children under 6 months of age. Parents with children under 6 months of age should severely limit their children’s sun exposure.
Nutrition and Skin cancer
Most experts agree that the sun’s damaging effect on the skin has to do with oxidative damage-that is, the sun’s UV (ultraviolet) radiation causes free radical formation, which damages the DNA of the skin’s cells and causes mutation, leading to cancer. The skin possesses an elaborate antioxidant defense system to deal with this stress. However, excessive exposure to UV light can overwhelm the skin’s antioxidant capacity, leading to oxidative damage and ultimately to skin cancer, and premature skin aging. Several studies have shown that people with a variety of sun-related skin disorders have lower levels of antioxidants.1,2 Indeed, in some patients with melanoma an imbalance of the antioxidant system has been identified.3
Replenishing the skin’s antioxidant capabilities is one way to decrease the risk of skin cancer. Studies are mixed about the benefit of individual antioxidants. Indeed, in some studies, it was found that too much of a single antioxidant could even have damaging effects. However, there are clear benefits to some antioxidants, and the most promising results were obtained in studies combining several compounds, often resulting in synergism of the protective effects.4
Vitamin E is the major naturally occurring lipid-soluble antioxidant protecting skin from the damaging effects of sun-induced oxidative stress.5,6 It also is believed to be a key factor in minimizing light induced damage to the eye. It has been shown to reduce the ability to reduce skin cancers in mice.7 It may work topically as well as orally. Because of it’s critical role, it is important to maintain adequate levels (400 to 800 IU per day). Vitamin E has also shown benefit in the prevention of prostate cancer.
Vitamin C is a water soluble antioxidant which has shown to be depleted in those people that develop skin cancer.2 It makes up an important part of the skin’s antioxidant system.
Niacin (Vitamin B-3)
Niacin has been shown to increase the level of NAD in the skin, which is known to modulate two proteins that are critical in the skin’s defense system against sun-induced damage. Thus, if damage occurs, it may be repaired prior to the transformation of a normal to a cancerous cell.8,9
Silymarin (Milk Thistle)
Although not an antioxidant that is naturally in the body, Milk Thistle (and it’s active component silymarin) is a powerful antioxidant with well documented beneficial effects on the liver. Several studies in mice have shown a potent effect of silymarin on reducing the occurrence of Stage I skin cancers, with specific mechanisms and enzymatic pathways being mapped out.10-14
Grape seed extract contains chemicals known as procyanidins which are potent antioxidants and have been shown to have anti-tumor properties in mice.15 Genistein, an antioxidant in soy, also shows some promise in the prevention of human cancers, including skin.16
Our Nutritional Recommendations
As we discussed above, skin cancer is quite prevalent; therefore, I believe we all should take steps to try and prevent it from occurring. The daily use of a broad spectrum multivitamin/mineral/antioxidant compound will be a cornerstone of prevention for skin, and other, cancers. In addition, because of the strong evidence in several mouse models of skin cancer development, persons at high risk for skin cancer should take Milk thistle each day.
Additional measures include:
A. Eating a low fat diet
B. Keep alcohol consumption less than 20 grams (2 drinks) per day.
C. Eat at least 5 portions of fruits and vegetables, especially cruciferous vegetables, each day.
Treatment of skin cancer
Treatments for skin cancers and precancerous lesions depend on their size, type, depth and location. Most treatments use a local anesthetic in an outpatient setting. For a detailed description of surgical treatment of skin cancer, please see our review of skin cancer in the science section.
1Van Dam RM; Huang Z; Giovannucci E; Rimm EB; Hunter DJ; Colditz GA; Stampfer MJ; Willett WC. Diet and basal cell carcinoma of the skin in a prospective cohort of men. Am J Clin Nutr 2000 Jan;71(1):135-41
2Vural P; Canbaz M; Selcuki D. Plasma antioxidant defense in actinic keratosis and basal cell carcinoma. J Eur Acad Dermatol Venereol 1999 Sep;113(2):96-101
3Picardo M; Grammatico P; Roccella F; Roccella M; Grandinetti M; Del Porto G; Passi S. Imbalance in the antioxidant pool in melanoma cells and normal melanocytes from patients with melanoma. J Invest Dermatol 1996 Sep;107(3):322-6
4Steenvoorden DP; van Henegouwen GM. The use of endogenous antioxidants to improve photoprotection. J Photochem Photobiol B 1997 Nov;41(1-2):1-10
5Nachbar F; Korting HC. The role of vitamin E in normal and damaged skin.
J Mol Med 1995 Jan;73(1):7-17
6Fryer MJ. Evidence for the photoprotective effects of vitamin E.
Photochem Photobiol 1993 Aug;58(2):304-12
7Slaga TJ . Inhibition of the induction of cancer by antioxidants.
Adv Exp Med Biol 1995;369:167-74
8Gensler HL; Williams T; Huang AC; Jacobson EL Oral niacin prevents photocarcinogenesis and photoimmunosuppression in mice. Nutr Cancer 1999;34(1):36-41
9Oral niacin prevents photocarcinogenesis and photoimmunosuppression in mice.
AUTHORS: Gensler HL; Williams T; Huang AC; Jacobson EL
AUTHOR AFFILIATION: Arizona Cancer Center, Department of Radiation Oncology, University of Arizona College of Medicine, Tucson 85724, USA.
SOURCE: Nutr Cancer 1999;34(1):36-41
10Zhao J; Sharma Y; Agarwal R . Significant inhibition by the flavonoid antioxidant silymarin against 12-O-tetradecanoylphorbol 13-acetate-caused modulation of antioxidant and inflammatory enzymes, and cyclooxygenase 2 and interleukin-1alpha expression in SENCAR mouse epidermis: implications in the prevention of stage I tumor promotion. Mol Carcinog 1999 Dec;26(4):321-33
11Zi X; Agarwal R . Modulation of mitogen-activated protein kinase activation and cell cycle regulators by the potent skin cancer preventive agent silymarin.
Biochem Biophys Res Commun 1999 Sep 24;263(2):528-36
12Lahiri-Chatterjee M; Katiyar SK; Mohan RR; Agarwal R. A flavonoid antioxidant, silymarin, affords exceptionally high protection against tumor promotion in the SENCAR mouse skin tumorigenesis model. Cancer Res 1999 Feb 1;59(3):622-32
13Ahmad N; Gali H; Javed S; Agarwal R . Skin cancer chemopreventive effects of a flavonoid antioxidant silymarin are mediated via impairment of receptor tyrosine kinase signaling and perturbation in cell cycle progression. Biochem Biophys Res Commun 1998 Jun 18;247(2):294-301
14Katiyar SK; Korman NJ; Mukhtar H; Agarwal R . Protective effects of silymarin against photocarcinogenesis in a mouse skin model. J Natl Cancer Inst 1997 Apr 16;89(8):556-66
15Zhao J; Wang J; Chen Y; Agarwal R . Anti-tumor-promoting activity of a polyphenolic fraction isolated from grape seeds in the mouse skin two-stage initiation-promotion protocol and identification of procyanidin B5-3′-gallate as the most effective antioxidant constituent. Carcinogenesis 1999 Sep;20(9):1737-45
16Wei H; Bowen R; Cai Q; Barnes S; Wang Y . Antioxidant and antipromotional effects of the soybean isoflavone genistein. Proc Soc Exp Biol Med 1995 Jan;208(1):124-30