Harvard Women's Health Watch

Squamous cell carcinoma: The skin cancer you haven’t heard about

It doesn't get as much attention as other skin cancers, but squamous cell cancer is common and serious.

From the Harvard Health Letter, May 2006

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 (from the keratin), well-defined, and occasionally crusty. Some you might mistake for a wart, only flatter. And there are those that are soft and fleshy. The pictures elsewhere on this Web page will give you an idea of what some of them look like.

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