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Skin Cancer

Non-Melanoma Skin Cancer

What are NMSCs? Non-melanoma skin cancers are the most common skin cancers. They arise from skin cells in the epidermis, the outer-most layer of the skin. The two most common NMSCs are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). BCC is the most common human cancer and accounts for 80% of all skin cancers. SCCs make up 16% of all skin cancers. BCCs and SCCs arise from keratinocytes, the cells that make up most of the epidermis. There are two main kinds of keratinocytes: basal cells that form the basal layer, and squamous cells that lie just above the basal layer. BCCs arise from basal keratinocytes, and SCCs develop from squamous keratinocytes.

Who gets NMSCs? NMSCs are most common on skin that has been exposed to a lot of ultraviolet (UV) radiation over time, either from natural sunlight or from tanning booths or phototherapy. There may be many years, or decades, between the time of significant UV exposure and the development of NMSCS. NMSCs are more commonly seen in individuals with fair skin, since they are more susceptible to UV-induced skin damage, however NMSCs can occur in people of all skin types and ethnic backgrounds. People with inherited genetic disorders (such as xeroderma pigmentosum or basal cell nevus syndrome), immune suppression (such as following a solid organ transplant), or who have been exposed to ionizing radiation (such as X-ray treatment for certain kinds of cancer) may also be at higher risk for developing NMSCs.

What do NMSCs look like? When they first appear, BCCs often look like pink bumps resembling "pimples" except that they don't go away. Over time, they may develop small dilated blood vessels on their surface ("spider veins"), and the center of the growth may repeatedly break open and scab. Other types of BCC may look like flat, pale pink, shiny "scars", sometimes with a slightly scaly surface. BCCs typically grow quite slowly. It is very rare for BCC to metastasize (spread to other parts of the body), therefore it is rare for BCC to be life-threatening. However, untreated BCCs will continue to enlarge and invade more deeply into the skin, and the results can be extremely disfiguring.

Compared to BCCs, SCCs may grow rapidly, and they often look like a large pink "wart" that is firm and tender to the touch. SCCs tend to have more scale than BCCs, and they sometimes have a central "crater" filled with firm, scaly material. Some SCCs arise from a preexisting actinic keratosis. Occasionally, SCCs develop from a non-healing "sore" such as a leg ulcer or from an old scar (especially a burn scar). SCCs are more likely to metastasize than BCCs, especially if they are located in high-risk areas such as the lip or ear. People whose immune systems are not functioning properly (such as solid organ transplant patients, the very elderly, or those with alcoholism) are also at higher risk for metastasis.

How are NMSCs treated? There are many different ways to treat NMSCs. Treatment options include destructions, chemotherapy, and surgery. Destructions are procedures designed to physically remove the NMSC by cutting, scraping, lasering, cauterizing ("burning"), or freezing with liquid nitrogen. A common destruction used to treat NMSCs is called electrodesiccation and curettage (ED&C), which is essentially a "burning and scraping" procedure. Topical chemotherapy, using drugs applied to the skin to remove the cancerous cells, can be used alone or together with destructions (especially ED&C). Surgery means cutting the NMSC out of the skin, either by way of a standard excision or Mohs micrographic surgery. The latter procedure, named after Dr. Frederick Mohs, is a highly specialized surgical technique that is indicated for tumors located in cosmetically sensitive areas (such as the nose, eyelid, lip, rim of ear), very large tumors, tumors with ill-defined margins, tumors with an aggressive microscopic appearance, or recurrent tumors.

Which treatment for NMSC is best? Which treatment option is best for each situation depends on many factors, including the tumor's size, location, microscopic appearance, as well as the age and general health of the patient and the ultimate cosmetic outcome of the procedure. Your dermatology health care provider can help you decide which treatment is most appropriate for each particular situation.

How can NMSCs be prevented? The risk of NMSC can be decreased by protecting the skin from excessive amounts of UV exposure. A combination approach to sun protection is most effective. Avoid prolonged time in the sun during the middle of the day (10am – 4pm), when the sun's rays are most intense. Seek shade when possible. Wear protective clothing to shield the skin, including hats and sunglasses. Apply sunscreen with at least SPF 15 twenty minutes before exposing skin to UV light, and reapply it every ninety minutes if you get wet, perspire a lot, or wipe off the skin. It takes one ounce of sunscreen to cover an average-sized adult from head to toe. Remember that UV light passes through clouds and window glass, so don't ignore sun protection on cloudy days or when traveling in vehicles. If patients have already had one NMSC, they are at higher risk for developing another, even if they are very careful about sun protection on an ongoing basis in the future. However, it is still important that they continue to practice careful sun protection measures. People cannot go back in time and undo the UV damage that has already occurred to their skin, but they can help prevent additional damage, which in turn may reduce their risk of future skin cancers.