Skin cancer is the most common cancer in both men and women. More skin cancers are diagnosed each year than all other cancers of all anatomic sites combined. Most skin cancers are either basal cell or squamous cell carcinoma. Basal cell carcinoma (BCC) develops from the basal layer of the epidermis while squamous cell carcinoma (SCC) develops from the keratinocytes in the epidermis. The epidermis is the layer of tissue just below the surface of the skin.
More than two million new cases of skin cancer are diagnosed each year, and this number continues to rise. Squamous cell carcinomas are usually slow-growing tumors that are easily treated. While these types of skin cancer tend to spread locally, rarely SCC can be aggressive and spread to surrounding lymph nodes. Melanoma is another type of skin cancer that is more serious and is discussed in a different section.
Symptoms of Squamous Cell Skin Cancer
Most skin cancers are detected based on the appearance of a skin lesion. Squamous cell carcinoma can occur anywhere on the skin surface, although most occur on the sun-exposed areas of the skin such as the head, face, hands, forearms and legs. SCC can appear as skin changes that include pink discoloration, peeling, swelling, ulceration, bleeding, thickening, or crusting. These signs/symptoms can mimic benign skin conditions such as eczema or acne. Typically the lesions will not heal and may continue to worsen despite good skin care. Evaluation by a healthcare provider is warranted.
Risk Factors of Squamous Cell Skin Cancer
Both environmental and genetic factors can increase a person’s risk for developing skin cancer. Sun exposure is the most important cause of squamous cell carcinoma. Those with fair skin, light-colored eyes, red hair and/or northern European ancestry are at increased risk of developing skin cancer due to UV damage from the sun. There is also an association with both the number and severity of past sunburns with the risk of skin cancer.
Chronic sun exposure is the most common cause of SCC. Tanning beds cause skin changes similar to chronic sun damage and can increase the risk.
A weakened immune system is also a significant risk factor for SCC. Examples of people with weakened immune systems include those who have undergone organ transplantation, have required long-term immunosuppressive medications such as steroids, or have HIV. Other less common risk factors include chronic exposure to arsenic (in drinking water or contaminated seafood) and radiation therapy (used to treat some types of cancer).
HowSquamous Cell Skin Cancer is Diagnosed
Squamous cell carcinomas have characteristic features that aid doctors in identifying suspicious skin lesions. However, biopsy is the preferred method for differentiating skin cancer from benign skin lesions. A piece of tissue is removed (biopsied), usually under local anesthesia, and examined under a microscope. If the cancer is small, the entire lesion may be removed during the biopsy. If it is larger, only a piece of the cancer will be removed.
Treatment Options for Squamous Cell Skin Cancer at Tufts Medical Center
Treatment depends on several factors, including:
- The size, type and location of the cancer
- The chances that the cancer is aggressive or likely to recur
- The person’s preferences regarding the appearance of the area after treatment
Low-risk skin cancers can be treated with cryosurgery, curettage and electrodessication (scraping and burning), topical therapy, or surgical treatment. Low-risk SCC may also be treated by radiation therapy.
- Cryosurgery uses liquid nitrogen to freeze the cancer. After treatment the area may become painful, swollen, and may form a blister. The treated area subsequently peels off, leaving a layer of healthy skin underneath which will heal and may leave a round, flat, whitened scar.
- Curettage and electrodessication is a form of electrosurgery that is performed in the office under local anesthesia. This procedure typically leaves a circular pink to white raised scar. It is not typically recommended for skin cancer on the face or head.
- Topical treatments include 5-FU (5-fluorouracil) and Imiquimod (Aldara). 5-FU works by inhibiting growth of the cancer cells. It is available as a cream or solution that is applied to the skin twice a day for several weeks. Side effects of 5-FU include irritation at the site, such as stinging, burning, pain, redness, swelling and ulceration or infection. Use of an emollient such as petroleum jelly or a steroid ointment can help soothe the irritation. Imiquimod works by activating the immune system. The cream is applied once or twice daily for several weeks. Imiquimod’s main side effect is skin irritation, but also can cause lightening of the skin color. Rarely patient’s can develop fatigue and/or body aches, which may limit treatment. The main advantage of topical skin cancer treatment is that it provides a favorable cosmetic outcome. After treatment the skin color may change, but this usually fades with time.
- High-risk skin cancers are usually treated by complete surgical removal of the growth. The surgical treatment is typically performed in the physician’s office or a surgery center under local anesthesia. The treated area is usually sutured closed, but large cancers may require a more extensive procedure that may include skin grafting or flaps. Mohs surgery is a specialized surgical technique performed by a specially trained dermatologic surgeon. This procedure also known as Mohs Micrographic surgery, entails ultra-conservative removal of the cancer to minimize the size of the wound. The excised tissue is immediately examined under a microscope to ensure all of the cancer is removed. If residual cancer is present (roots of cancer spreading beyond what was initially removed) the Mohs surgeon can go back, usually in less than one hour, and remove more tissue – specifically and precisely in the location of the root, without sacrificing normal tissue. Once the tumor is completely removed the wound is closed with sutures (stitches). The entire procedure, Mohs surgery and the cosmetic reconstruction is performed in one day. Cure rates with Mohs surgery approaches 95-99%. The Dermatologic Surgery Program at Tufts Medical Center is unique in that the Mohs surgery can be coordinated with specialized reconstructive surgeons, eye plastic surgery, facial plastic surgery or hand surgery, such that the patient can have the expertise of the Mohs surgeon and cosmetic surgeon in one visit to the Center.
- Radiation therapy (RT) is another option for high-risk skin cancers that cannot be removed surgically. It is typically reserved for patients who are unable to tolerate surgery or to elderly patients with large tumors. RT involves the use of focused; high energy x-rays to destroy cancer cells. Treatments are brief and are not painful. The treatment is administered as small doses of radiation given daily over a few seconds each day, five days per week, for several weeks.
Rarely squamous cell carcinoma can spread (metastasize) to nearby lymph nodes. If any lymph nodes feel enlarged or abnormal, further examination with imaging (CT scan or MRI) or biopsy may be warranted. If any cancer cells are found in the lymph nodes, treatment usually includes surgical removal of the lymph nodes as well as radiation therapy.