In the United States, skin cancers are the most common of all cancers in Caucasians, occurring more frequently in males than females, and increasing with age. Due to ultraviolet (UV) radiation, people who live at higher altitudes or closer to the equator are at higher risk for skin cancers. Lesions occur most commonly in areas of the skin exposed to the sun. There are three types of skin cancer. Basal cell cancer (BCC) and squamous cell cancer (SCC) are often referred to as nonmelanoma skin cancers (NMSC) because of similarities in treatment and outcome. They often require extensive and recurrent treatment but have low metastatic and mortality rates. BCC and SCC account for less than 0.1% of patient deaths due to cancer. According to the American Cancer Society, 1.3 million cases of nonmelanoma skin cancer occur in the United States each year. Approximately 2,200 deaths occurred in 2002 due to nonmelanoma skin cancer. Nonmelanoma skin cancer has greater than a 95% cure rate when diagnosed in the early stages. Malignant melanomas (MM) have a higher mortality and metastatic rate but are less common.

A. BCC is the most commonly occurring cancer, with almost 1 million new cases diagnosed annually in the United States. It begins in the epithelial tissue, most frequently on the head and neck. It is usually slow growing, and it invades and destroys surrounding tissues including bone, cartilage, and blood vessels.

B. Approximately 200,000 new cases of SCC are diagnosed annually in the United States. SCC also begins in the epithelial tissue but is faster growing and more irregular in shape than BCC. It commonly appears on mucous membranes of the face (lower lip, tongue) or on the ears or back of the hands. Metastatic potential is greater than with BCC.

C. MM arises from the melanocytes, which generate and transport melanin. These cells are in the basal epidermis, the eyes, meninges, lymph nodes, and alimentary and respiratory tracts. Incidence of MM has increased faster than any other cancer over the past 20 years. Although comprising only 4% of skin cancers, MM is responsible for about 75% of the deaths from skin cancer worldwide.

A. Risk Factors

1. People with light skin and hair color or who are otherwise prone to sunburn are at increased risk for all skin cancers. A history of early sunburn or intense intermittent sun exposure increases the risk of MM.

2. Advanced age is a risk factor for both BCC and SCC.

3. History of skin trauma, overexposure to ionizing radiation, long-term arsenic ingestion, xeroderma pigmentosum, history of immunosuppression (organ transplantation, human immunodeficiency virus [HIV]), and scarring skin diseases (discoid lupus erythematosus, lupus vulgaris, chronic skin ulceration) also increase risk for BCC and SCC.

4. Nevoid BCC syndrome is a hereditary disorder characterized by development of BCC early in life. Affected people usually develop the disease by age 20 and may have over 100 BCC lesions.

5. Actinic keratoses (AK) due to chronic sun exposure have the potential to develop into SCC.

6. Several hereditary syndromes may be involved in development of a small percentage (5% to 12%) of MM: familial multiple mole melanoma syndrome (FAMMM), dysplastic nevus syndrome, and atypical mole syndrome.

B. Environmental Factors

1. Exposure to UV rays of the sun has been implicated in all types of skin cancer. Recommendations for avoiding UV exposure include use of sunscreens (SPF 15 or higher), wearing sun-protective clothing (long sleeves, hats), and avoiding sun exposure during peak times of 10 AM to 4 PM. It is not clear whether use of sunscreens actually reduces risk of MM because there is some evidence that it actually increases duration of sun exposure.

2. Mutations of the tumor suppressor gene p53 have been described in AK and skin cancers. In these instances, p53 mutations are most likely due to damage from UV rays of the sun, primarily UVB and UVC wavelengths, which are filtered by the stratospheric ozone layer.

A. Assessment: The following are signs and symptoms of skin cancer:

1. Basal cell carcinoma (BCC)

a. White, pink, or skin-colored, waxy lesions are characteristic of the most common type of NMSC: Noduloulcerative BCC. The lesion appears as a firm, well-circumscribed, raised papule. It is commonly found on the face, head, or neck, and ulcerates and may bleed as it develops.

b. Flat, red, or pink scaling is often the appearance of superficial BCC, which is also a common NMSC. It is usually well circumscribed and is most often found on the limbs or trunk.

c. Black, brown, or blue lesions found on the face, head, or neck may be pigmented BCC. It is similar in appearance to MM but is like nodular BCC in growth.

d. A flat, ivory, scarlike lesion on the head or neck may be morpheaform BCC. Although rare, it is more aggressive than other BCC.

e. A hornlike growth in the postauricular sulcus may be a keratotic (or basosquamous) BCC. This is the most aggressive BCC and frequently recurs and metastasizes.

2. Squamous cell carcinoma (SCC)

a. Keratinization and keratin pearl formation in the epithelium are typical in SCC but are less evident as the tumor becomes more advanced.

b. Raised, firm papule, which is red or flesh colored, is usually the initial appearance.

c. A crusted, ulcerated, and indurated lesion may appear as it spreads to surrounding tissue.

d. Symptoms include pain in skin that has been exposed to UV rays.

e. Tumors may be found in scar tissue of radiation, chemical, or thermal burns or in areas of chronic inflammation.

3. Malignant melanoma (MM): There are three precursor lesions of MM.

a. Dysplastic nevi (DN) occur in familial and nonfamilial patterns. Familial DN are not common, but risk of people with DN developing MM is almost 100%. The general population risk of nonfamilial DN is 5% to 10%.

(1) DN usually have some clinical features of MM, which may include color, asymmetry, or irregularity of shape. DN occur in clusters (100 or more) and are found on the face, trunk, arms, buttocks, groin, scalp, and female breasts.

(2) Colors vary and may be tan to brown, black, red, or pink.

b. Congenital nevi are present at birth and may be as small as 1.5 cm or may cover extensive areas of the body.

(1) There is a lifetime risk of malignant conversion of about 7%.

(2) Lesions are brown to black in color and may be slightly raised with regular borders and areas of nodularity.

c. Lentigo maligna is similar to its counterpart lentigo maligna melanoma (see types of MM listed below).

4. Classification of MM: There are four major types of MM.

a. Lentigo maligna melanoma is found on body areas with frequent sun exposure (face, neck, arms, legs). It grows slowly, in a radial pattern, for many years before beginning a vertical growth phase. It is characteristically large (about 10 cm) in size and may be tan or brown with irregular borders. In the vertical phase, nodules appear on the surface.

b. Superficial-spreading melanoma accounts for about 70% of MM. In men, it is often on the trunk; whereas lesions in women are more commonly on the legs. The radial growth phase is about 1 to 5 years. Lesions appear flat and tan/brown with a scaly surface. In the more aggressive vertical phase, color may change to red, blue, or white and the lesion may be ulcerated.

c. Nodular melanoma occurs commonly on the head, neck, or trunk, and begins with a rapid vertical growth phase. It appears as a dome shape with blue-black or red color, and it may ulcerate or bleed.

d. Acral lentiginous melanoma is the least commonly occurring MM but is the most common type seen in dark-skinned people (35% to 60%). It occurs on the mucous membranes, soles of feet, palms of hands, and nail beds. The radial phase lasts 2 to 5 years and looks similar to lentigo maligna. The vertical phase
has areas of nodularity and is more aggressive in growth. It has high potential to metastasize and has the poorest survival rate of the MM types.

B. Diagnostic Parameters

1. Assessment of a lesion suspected as MM

a. Establish when the lesion was first noticed and any change in appearance. (Note changes in color, size, or shape; personal and family history of skin cancers or DN; sun exposure; and skin injury or trauma.)

b. Evaluate the lesion by the “ABCD” method. Assess for A, asymmetry; B, border irregularity; C, color changes; and D, diameter more than 0.6 cm.

c. Palpate lymph nodes, with special attention to those regionally adjacent to the lesion.

2. Cytogenetic analysis is being studied as a predictor of hereditary predisposition for MM. Although abnormalities are frequently found on chromosomes 1 and 6, clinical indications are not clear and more research is required.

3. Biopsy is the only accurate diagnostic procedure for skin cancers. For suspected NMSC, three techniques are commonly used.

a. Punch biopsy samples a thick section of the lesion with a special tool.