A squamous cell carcinoma (or SCC) is a skin cancer that may appear as a bump or as a red, scaly patch. It often is found on badly sun-damaged, fair skin, and because of this often develops on the rim of the ear, the face, and the lips. It is not as dangerous as melanoma, but still leads to an estimated 2,300 deaths every year. When properly treated the cure rate is 95 percent. In rare cases, SCC may spread to the lymph nodes in the area resulting in a metastasis of the cancer to other areas of the body.
SCC’s develop in several different circumstances and vary greatly as to how dangerous they are. Like other forms of cancer, such as cervical and colon, they may be closer to pre-cancerous, highly malignant or somewhere in between. Most develop out of actinic keratoses (rough sun spots), some from old wounds, and some due to a weakened immune system.
The most common types of SCC are Bowens disease (“SCC in situ”) and keratoacanthoma. These types are only rarely a threat, but could develop into a more dangerous type if not treated promptly. At times, aggressive SCC will be found that looked like a different type of skin cancer, so only a biopsy can determine what the risk is with certainty.
Bowens disease looks like a dry rough patch. Prior to seeing a dermatologist, it is often thought to be a fungus or rash. Keratoacanthoma is a rapidly forming lump with a central dry core. It is frequently thought to be a “boil” or cyst before evaluation. The risk of metastasis is probably under 1%.
SCC’s that are invasive are more dangerous. They most commonly appear as a lump, and are often open sores that bleed easily. The risk of metastasis is around 3%. Some of these may be considered high risk because of size, location or features seen on the biopsy. They may be found on the ear, lip or in an old wound. They are larger, deeper, and may invade nerves or have cell that are “poorly differentiated”. The risk of metastasis from a high risk SCC runs from 10 to 30%.
The treatment for an SCC depends on its type, location and risk. For most SCC the best treatment is excision (the SCC is cut out and the hole stitched up). Along with a surrounding strip of normal appearing skin, this is sent to a pathology laboratory. The lab checks to confirm complete removal complete removal of the SCC.
High-risk tumors are best treated by wide excision (removal of a large margin of normal skin) or Mohs’ Surgery. Mohs surgery is a specialized microscopically controlled surgical technique that removes the entire tumor, and only the tumor. It has the highest cure rate, and is the least disfiguring. If used on larger cancers or on a difficult site a dermatologic surgeon or plastic surgeon may also be needed to repair the defect left after excision. Mohs surgery should almost always be used if the SCC comes back at the same site (recurs).
Once a person has developed one SCC, he is always at risk of developing another one. The actinic keratoses on the skin are the breeding ground for future SCC and these should be treated. One may also be at risk for other forms of skin cancer. Regular dermatology examinations, at least twice yearly, will be needed.
The best way to avoid developing more skin cancers is to protect the skin from further sun damage. Use sunscreen of at least SPF30 and wear a broad brimmed hat. Eat a healthy, low fat diet. Early treatment of SCC makes treatment easier, so learn the signs of skin cancer, and check the skin once each month. Promptly seek care for any suspicious growths.