The Truth About Melanoma and Skin Cancer: Facts and Common Myths

Often caused by excessive exposure to ultraviolet (UV) rays in sunlight, melanoma accounts for only 4 to 5 percent of skin cancer cases, but is responsible for most skin cancer-related deaths. As with many forms of cancer, melanoma is often misunderstood, and myths persist.

When detected and treated in its earliest stages, however, melanoma is often curable. The key is to avoid overexposure to UV rays – by limiting time outdoors during the peak hours of sunlight and wearing sun-protective clothing and sunscreen – and to be on the lookout for changes in moles and other blemishes that can be an early sign of the disease.

Jennifer Y. Lin, MD, of Dana-Farber Cancer Institute’s Melanoma Treatment Program, sets the record straight on five of the most common myths about melanoma.

Myth 1: A diagnosis of melanoma means that I have months to live.

There are four stages of melanoma — five if you include a form known as melanoma in situ, an early form of the disease that affects only the top layer of skin. Stage 1 melanomas, which are less than one millimeter thick and almost always have not spread beyond their original site, have an excellent prognosis and are generally cured by surgery. The depth of the original melanoma is critical to determining how it will be treated and how people with it are likely to fare. Although more melanomas are being diagnosed, the largest portion are made up of Stage 1 melanomas. Before worrying about the worst outcomes, speak with your doctor about what stage melanoma you have.

Myth 2: There is no difference between SPF 30 and SPF 100 sunscreen.

Although the baseline protection from SPF 30 and SPF 100 is not vastly different, the higher number provides longer coverage. (SPF stands for sun protection factor, or the amount of ultraviolet radiation the skin can absorb without burning while the sunscreen is on.)

If it normally takes you 10 minutes in the sun to burn, an SPF 30 sunscreen protects you for 300 minutes. An SPF 100 should, in theory, provide 1,000 minutes of coverage. If you are sweating and active, the sunscreen can rub off and should therefore be reapplied every two hours. When you are using a high SPF, there is a smaller likelihood of having a “missed spot.” A good way to know that you are applying enough sunscreen is to use the measurement of a shot glass of sunscreen for exposed sites.

Myth 3: If it is a cloudy day, I do not need to wear sunscreen.

About 80 percent of ultraviolet radiation reaches the earth even through clouds. Use a moisturizer with sunscreen daily, especially for areas that have high exposure, such as your face.

Myth 4: If I am low in vitamin D levels, I must get some sun exposure.

Although the skin is the most efficient site of vitamin D production, adequate amounts can be obtained from your diet and from supplements. Vitamin D helps you absorb calcium and build strong bones, so we frequently recommend supplements that include vitamin D and calcium.

Myth 5: If I have dark skin, I can’t burn and won’t get melanoma.

Even people with dark skin can burn if they’re exposed to the sun long enough. Although melanoma is much more rare in individuals of darker skin, it can occur. We recommend that darker-skinned individuals inspect their hands and feet once a month.

Learn more about skin cancer and melanoma from Dana-Farber Cancer Institute.