Squamous Cell Carcinoma
Background
Squamous cell carcinoma (SCC) is a cancer that arises from squamous cells, which are flat, scale-like cells that compose most of the upper layer of the skin. Squamous cells also line passageways and hollow organs in the body including the lungs, esophagus, cervix, mouth, nasal passageways, and throat. SCCs are relatively slow-growing malignant tumors which can spread to surrounding tissue if left untreated. Distant metastasis is rare but can occur. Squamous cell carcinoma is the second most common skin cancer in the United States, with more than 200,000 new cases reported per year.
Causes
Most cases of squamous cell carcinoma are caused by over exposure to the sun, and incidence is much higher in geographic locations with more frequent and/or intense sun exposure. Areas of the skin that have been scarred, burned or subject to X-rays are also more likely to develop SCC.
Tobacco use is linked to squamous cell carcinomas found in the mouth, throat, and nasal passageways, as well as in the lungs. SCC in the nasal and paranasal sinuses has been associated with exposure to certain chemicals, including nickel, chromium, mustard gas, and isopropyl alcohol. Chronic sinusitis may also play a role in the development of SCC in the sinuses but it is controversial.
Risk Factors
- exposure to UV light
- geographic location (near the equator)
- fair skin
- previous skin cancer
- scarring
- tobacco use, including cigarettes, pipes, cigars and chewing tobacco
- radiation exposure
- conditions which compromise the immune system
- gender: males are more susceptible
- older age
- exposure to certain chemicals including arsenic, chromium, radium and mustard gas
Symptoms
In many cases, squamous cell tumors develop from pre-cancerous lesions called actinic keratosis (AK). An AK presents as an abnormality on or just under the surface of the skin—it is a small, scaly area that may be flat or raised, and may be darker, lighter, pink, red, or the same color as the skin. These lesions grow very slowly and may disappear and then reappear later. They occur on areas of the body most frequently subjected to sun exposure, particularly the face, lips, scalp, back of the hands and forearms, shoulders, and neck. Approximately 40-60% of SCCs arise from untreated AKs. Not surprisingly, squamous cell tumors have a similar presentation—a rough, scaly patch or elevated growth on the skin, which may develop into an open, persistent sore that bleeds and crusts.
Within the mouth, throat, or nose an SCC tumor also typically presents as a persistent sore, discolored patch or lump, and is often accompanied by persistent pain.
Diagnosis
A physical examination of the lesion, along with a patient history that includes risk factors relevant to its location is often sufficient to make a diagnosis. SCC is confirmed by a biopsy of the lesion. Imaging studies (MRI, CT scan) are performed if spread is suspected.
Cases of SCC not accessible for physical examination, i.e. in the sinuses rather than on the skin, require imaging studies to identify the presence and exact location of the tumor. Biopsy follows.
Treatment
Treatment varies based on the location and size of the tumor. Cutaneous lesions are often treated with topical chemotherapy or radiation. Larger tumors are surgically removed.
The endoscopic endonasal approach (EEA) is a state-of-the-art surgical procedure that can be used to treat squamous cell carcinomas of the nasal cavity, paranasal sinuses and skull base.
For more advanced tumors, postoperative radiation therapy is often utilized as well.
Prevention
Reduce UV exposure by limiting time spent in the sun, especially during midday, when sunlight is most intense. Apply sunscreen daily, even on cloudy days and in the winter. New growths in the skin, changes in moles and other existing growths, and slow healing ulcers should be reported to a physician. Early diagnosis and treatment may prevent a precancerous lesion from becoming malignant and may help to avoid more serious complications of a malignancy.
For sinonasal malignances, tobacco use should be stopped since it is linked to squamous cell carcinomas found in the mouth, throat, and nasal passageways, as well as in the lungs. Exposure to certain chemicals, including nickel, chromium, mustard gas and isopropyl alcohol must be avoided. Chronic sinusitis must be medically or occasionally surgically treated as well as nasal polyps and papillomas.