There are over 800,000 cases of skin cancer diagnosed each year in the United States.  The most common types may be disfiguring or annoying, but are not commonly fatal.  The leading cause of skin cancer is sunlight, particularly the ultraviolet portion of the spectrum, which causes DNA damage in skin cells that is not successfully repaired.  About 95% of squamous cell carcinomas and 70% of basal cell carcinomas in North America occur in blue-eyed blondes.  African-Americans rarely suffer from these diseases.  Skin cancers increase in incidence as one goes from northern latitudes to more southern latitudes.  Fair-skinned persons whose hobbies or occupations lead to frequent sun exposure are at high risk. 

     In addition to squamous cell carcinoma and basal cell carcinoma, some other important types are melanoma and Merkel cell carcinoma because, while less common, they are more dangerous.  Kaposi’s sarcoma has become more common recently because it may be associated with AIDS.

    In-depth Information

    Basal Cell and Squamous Cell Carcinomas

     Basal cell carcinomas and squamous cell carcinomas of the skin constitute the vast majority of skin cancers. In most cases, they occur on sun-exposed parts of the body such as the head, neck, and arms of fair-skinned people. In many cases, diagnosis and treatment may be one step: the doctor excises a small skin lesion with a scalpel and sends it to the pathology laboratory.  Basal cell cancers almost never spread to lymph nodes or distant sites, and squamous cell carcinomas do so only in a small percentage of cases.  The need for additional treatment depends on factors such as recurring disease in the same site or the stage of the disease or occurrence at certain problematic sites. The staging system for these common skin cancers is as follows:

    TNM Staging System

     A variety of techniques are used to treat basal cell and squamous cell skin cancers.  Simple surgical removal may suffice for small tumors in non-critical areas.  Radiation therapy may be preferred for skin cancers in critical locations such as the eyelid or on the nose, where surgery would be disfiguring.  Radiation therapy also may be indicated for deeply infiltrating skin cancers or cancers recurring after an attempt to cure by surgery.  Some of the specialized surgical methods that might be employed include cryosurgery (freezing the tumor) or Moh’s micrographic surgery.

    Melanoma

     Melanoma accounts for less than 2% of skin cancers, but is of concern because it is more deadly than basal cell or squamous cell cancers.  Statistics for 1999 suggest that there would be 44,200 new cases and 7,300 deaths due to melanoma.  In recent decades, melanoma seems to be doubling every 10-12 years.  It usually occurs on the skin of fair-skinned people, and is more common in locations nearer the equator than near the poles of the earth.  It is rare in dark-skinned people.  There is some tendency for melanoma to occur on the limbs of women and the head and trunk of men. Women have a small advantage in survival.  A melanoma is a brownish colored lesion that starts in a cell named the melanocyte.  These cells are commonly present in the skin, but also in other places in the body, such as the gastrointestinal tract.  A melanoma can, therefore, start elsewhere in the body, although it usually originates in the skin.  A melanoma may either start as a transformation of a pre-existing benign mole, or without an apparent precursor mole.  Changes that should lead to inquiry are the appearance of a new pigmented spot, change in appearance of an existing pigmented spot, and crusting, bleeding, or persistent itching of a pigmented spot.

     Three main types of melanoma are distinguished.  The most common type is superficial spreading melanoma which displays a horizontal growth pattern within the epidermis with some invasion into the underlying dermis.  Nodular melanoma tends to a vertical growth pattern and is more dangerous.  Lentigo maligna melanoma displays a plaque like radial growth and usually occurs in rather elderly people. The hazard to the individual increases with the depth of invasion of the primary melanoma lesion, or with the involvement of regional lymph nodes at diagnosis, or with the presence of distant metastases at diagnosis.  The mainstay of treatment of melanoma is surgical removal of the lesion with a margin of normal tissue around it.  This is examined in the pathology laboratory to help in determining the staging of the disease.  Radiotherapy is sometimes used to treat a tumor bed if the margin of resection is questionable and a wider re-excision is not practical, or to treat nearby lymph node areas, or for palliative treatment if the disease becomes wide spread.

    Merkel Cell Carcinoma

     Merkel cell carcinoma is a rare but dangerous form of skin cancer.  These cells are found predominantly around hair follicles and are thought to function in the sense of touch.  The Merkel cell tumor often appears as a small pink-red nodule, occurring most commonly in the head and neck region.  These tumors have a tendency to extend more widely than suspected by appearance, to involve lymph nodes early in their course of development, and to seed distant metastases. 

     The initial approach in treatment of Merkel cell carcinoma is surgical removal of the tumor, but there is a high risk for local-regional recurrence of the tumor when treated by surgery alone. When the tumor does recur, it presents an increased risk of distant spread.  Merkel cell carcinoma is quite sensitive to radiation, and several studies now indicate that postoperative radiation treatment improves the chances for local control and cure of this disease.

    Kaposi’s Sarcoma

     The classical presentation of Kaposi’s sarcoma was as a reddish brown lesion on the legs of elderly males of Mediterranean ethnic origins.  Since the 1980s, it most commonly appears in association with AIDS.  The lesion is usually reddish brown or purple, and may be either a flat plaque or a nodular irregular disease process.  It is commonly a skin lesion, but can also occur on mucosal surfaces such as in the mouth.  The lesion is a highly vascular tumor, meaning that it contains many small blood vessels.  Kaposi’s sarcoma can involve the gastrointestinal tract, and symptoms related to this area may need to be evaluated by endoscopy.  Kaposi’s sarcoma can be disfiguring or very uncomfortable, but it is less likely to be the life-terminating feature of AIDS than the severe infections associated with immune deficiency.  Chemotherapy may be an option for multiple widespread lesions, but can also have the disadvantage of further compromise of an already weakened immune system.  Surgery or cryosurgery is sometimes used, particularly for small lesions.  Kaposi’s sarcoma is, however, very sensitive to radiation, and a short course of treatment will usually give a very satisfactory response.

    Research & Clinical Trials

     At Emory University, we participate in a number of clinical trials to treat skin cancer.  Click here to learn more about our clinical trials center.

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