Squamous cell carcinoma, or spinocellular carcinoma, is a cancer of keratinocyte cells in the outer layer of the skin. It is the second most common type of skin cancer. Squamous cell carcinoma is found on the skin and mucosal borders. Similar to basal cell carcinoma, it takes a long time for a premalignant lesion to become cancerous. Squamous cell carcinoma is presented in areas exposed to the sun; typically on the lower lip, the face or the back of the hand. Squamous cell carcinoma rarely metastasises. When located on the lip, it is more likely to metastasise compared with the other types.
Risk of disease
Solar UV radiation causes 60–90% of skin cancers. Sunburn and continuous exposure to sun (in outdoor work, etc.) cause skin cancer. Squamous cell carcinoma also has other causes, such as exposure to arsenic, radiotherapy, chemotherapy and medication that weakens the immune system. In addition, genetic factors contribute to the risk of squamous cell carcinoma.
Actinic keratosis is a pre-cancerous condition that can lead to squamous cell carcinoma. It is a reddish, round and sometimes flaky spot on the skin. An early lesion is often a superficial crusted area on the skin, under which can be found a distinct ulcer surface, indicating disintegration of the basement membrane. At the time of diagnosis, the diameter of squamous cell carcinoma is usually one to three centimetres. If left untreated, the nodule grows large and penetrates deeper into the tissue.
Distinct skin cancer tumors can be identified visually without any specific instruments. The doctor may further define the diagnosis by dermatoscopy. Often the patient notices the tumor and goes to see a doctor. When squamous cell carcinoma is suspected, it is important to know the patient’s history, such as how long the lesion has been visible, whether it has grown in size and how much the patient has been exposed to radiation. When necessary, a tissue sample is taken in order to verify diagnosis.
Surgery is nearly always the main treatment of squamous cell carcinoma. Radiotherapy is used much less frequently. If the tumor is widespread or its location is difficult (lips, eyelids), skin grafting or flap surgery is often necessary. Anticancer drugs may be used if the disease has spread.