The skin cancer you haven't heard about
Summer's the season for fun in the sun — but also for skin cancer. Of the three main types of skin cancer, melanoma is most deadly, and basal cell, most common. Squamous cell cancer falls in between. It's three times as common as melanoma (some 200,000 new cases each year versus 62,000). Though not as common as basal cell (about one million new cases a year), squamous cell is more serious because it is likely to spread (metastasize). Treated early, the cure rate is over 90%, but metastases occur in 1%–5% of cases. After it has metastasized, it's very difficult to treat.
What it looks like
Squamous cell cancer involves the runaway growth of keratinocytes, cells in the outermost layer of skin, which produce the protein keratin. Squamous means scaly; in 60%–80% of cases, the lesions emerge on or near scaly patches called actinic keratoses that develop from sun-damaged skin.
Typically, such lesions are hard, well-defined, and occasionally crusty. You might mistake one for a wart, only flatter. Others are soft and fleshy.
Exposure to sunlight is the main risk factor for skin cancer. For melanoma, sporadic instances of intense exposure seem to be triggers. For squamous cell cancer, cumulative exposure and possibly the intensity of the sunlight may be more significant. As with all skin cancers, skin color is relevant; those with darker skin have lower rates of squamous cell cancer than Caucasians — and among Caucasians, lighter-skinned people are more vulnerable.
Organ transplant recipients are especially vulnerable to squamous cell cancer. The most likely explanation is that the drugs that transplant patients take to suppress their immune systems and prevent organ rejection also make them vulnerable to this skin cancer. Chronic inflammation is another risk factor. The squamous cancers sometimes emerge from chronically inflamed scars or sores.
Treatments for squamous cell cancer all have the same goal: Get rid of the cancer cells, while avoiding unnecessary harm to surrounding skin.
Cryotherapy (rapid freezing) and radiation are used if the lesion is small and not likely to metastasize. Cryotherapy is fast and inexpensive but can leave a whitish mark. Radiation gives the doctor pinpoint control, minimizing damage to healthy skin, but it's expensive, involves many visits, and could result in a more aggressive case if the cancer recurs. Ointments are useful if there are many lesions but can cause stinging, burning, and oozing.
Surgery is the main therapy for larger lesions.
Sun safety is fairly straightforward. Avoid being outdoors between 11 a.m. and 4 p.m., when the sun is most intense. Remember that exposure doesn't just happen at the beach. By some estimates 80% of it is incidental to everyday activities like walking the dog, running errands, and so on. Noses, ears, and necks are especially vulnerable, so wear a wide-brimmed hat. .
Sunscreen isn't a magic shield. The National Cancer Institute (NCI) says the evidence that it prevents squamous cell skin cancer is only "fair." (For basal cell cancer and melanoma, the NCI says there is inadequate evidence to know if sunscreen is preventive.) Sunscreen users should buy one with a sun protection factor (SPF) of at least 15. Be sure to put on enough lotion. You need almost three tablespoonfuls on your face, neck, arms, trunk, and legs per application. At least a teaspoon should go on your face and neck.
June 2006 update