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Skin Cancer Causes, Warning Signs and Prevention: 7 Questions and Answers


by Kenneth Mark, M.D.

Ah, summer—time for bare skin, hot sun ... freckles, wrinkles, skin cancer ... oh, and vitamin D.

A dermatologist looks at the warmer months a little differently than other people. (No, a tan is not “healthy”!) Here, I answer some frequently asked questions about the sun, your skin and skin cancer.

1. What does the sun do to the skin?
The sun emits ultraviolet radiation, which causes changes in the skin. The changes can include:

  • wrinkles
  • skin laxity and sagging
  • coarseness or rough skin
  • hyperpigmentation and hypopigmentation (blotchy or mottled skin)
  • lentigines (sun spots)
  • telangiectasias (thin, visible blood vessels)
  • purpura (the purple, bruised blotches that can be prominent on the thinned dermis of the elderly)
  • skin cancers

2. What are some kinds of skin cancers?

Basal cell and squamous cell carcinomas are the most common, accounting for well over one million skin cancers per year. Melanoma is far more serious, with a significantly greater risk for spreading to other parts of the body and/or causing death.

  • Basal (BAY-sal) cell and squamous (SKWAY-mus) cell carcinomas are slow-growing cancers that seldom spread. However, it’s important to catch and treat them early because they can invade and destroy nearby tissue.
  • newsletter-graphic

    Melanomas, which usually begin in moles, can spread quickly and are the most deadly of the skin cancers.

Sun-induced skin cancers account for about 50 percent of all cancers. Skin cancers are being detected in increasingly younger patients. In fact, the number-one form of cancer in women ages 25 to 29 is melanoma.

3. What does skin cancer look like?

Here are some pictures of common skin cancers, from the National Cancer Institute. But cancer has a variety of appearances, so any change in your skin may mean a visit to the doctor is in order.

basal cell carcinomaA basal cell carcinoma can be small and reddish or translucent (perhaps pearly). It may have a central depression with rolled borders.


melanomaThis melanoma is asymmetrical and has an irregular border. Other potential signs of a melanoma include: diameter larger than about 1/4 of an inch, color variations, and changes in appearance or size.

squamous cell carcinomaThis is an advanced version of a squamous cell carcinoma. In these cancers, the surface is usually scaly and often ulcerates (as seen here on a patient's nose).




4. What are the risk factors for getting skin cancer from the sun?

Genetics play a significant role in the body’s ability to prevent sun damage and skin cancer. Specific risk factors include:

  • red or blond hair
  • fair skin
  • blue eyes
  • increased numbers of freckles
  • a personal history of a skin cancer

Family history is particularly important in the development of melanoma. Frequent childhood sunburns are also a significant risk factor for skin-cancer development. A large study in Germany showed that children who had greater sun exposure developed significantly greater numbers of freckles and moles, both of which are risk factors for melanoma.

That said, even the development of a tan is a sign that significant damage has occurred; the tan is the body’s response to the injury of the sun’s rays.


5. How can I prevent sun-related skin cancer?

While 80 percent of the sun’s damage to our skin occurs before the age of 18, there are important interventions that adults can and should undertake.

  • Avoid the sun between 10 a.m. and 2 p.m. (preferably until 4 p.m.).
  • Take steps to block the sun’s rays from getting to your skin. The Australian public relations campaign “Slip! Slop! Slap!” gained international notoriety for slip on a shirt, slop on sunscreen and slap on a hat.
  • Use a broad-spectrum sunscreen (both UVAand UVB protection) with an SPF of at least 45 and apply it at least 20 minutes before going outside. Many sources recommend an SPF of at least 15, but using a higher SPF helps offset the improper application that commonly occurs. In fact, when people apply a 15, they commonly gain an actual protection of about a 4!

6. How often should I get screened for skin cancer?

I recommend:

  1. Getting a complete skin-cancer screening by a board-certified dermatologist once a year. The fact that melanoma can kill and is clearly not just a disease of the elderly underscores the importance of annual screenings for patients of all ages. For people who have had a basal- or squamous-cell carcinoma, the skin-cancer checks should be performed at least every six months. After the initial detection of a melanoma, it would not be uncommon to get checked every three months.
  2. Doing self-examinations in addition to your doctor visit. Look for any non-healing red, scaly or crusty areas—particularly those that bleed—along with any unusual-looking, pigmented areas that look different than the rest of your moles or freckles.

7. Doesn’t the sun do anything good for me?

Certainly! Along with adequate calcium intake, the sun plays a major role in the body’s ability to make vitamin D. But the good news is that we do not need to experience redness or a sunburn to have adequate vitamin-D metabolism. Sun exposure on the hands, face and arms a mere two to three times per week is more than adequate—even for people who live in climates where they can only make vitamin D in the spring, summer and fall. The reason is that vitamin D is fat-soluble and can therefore be stored in the fat and released when needed.

The sun’s ultraviolet radiation, depletion of the ozone layer, and increasing use of tanning salons, along with an aging population, have led to an epidemic of skin cancer. The irony is that people like the sun and a tan because they think they look better. In the long run, these same appearance-conscious people are allowing the sun's rays to cause damage in the form of wrinkles; blotchiness; brown spots; and small thin, visible blood vessels. At the same time, they are increasing their risk of developing skin cancers which could require surgery and the inherent risks of scarring. A tan may look good to you now, but too much can do long-term damage—to your appearance and possibly your health.


is a board-certified dermatologist in Southampton and Easthampton, New York.

Last updated and/or approved: April 2010. Original article appeared in summer 2004 former print magazine. Bio current as of summer 2004. This article is not meant as individual advice. Please see our disclaimer.


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