How common is skin cancer in the United States?
There are currently approximately 3.5 million new cases of skin cancer in the United States annually making skin cancer the most common type of cancer. The incidence rate has increased dramatically over the past two decades. Sharply increased skin cancer rates have been reported worldwide.
What are the two most common types of skin cancer?
Basal cell carcinoma (BCC) is the most common type of skin cancer. It accounts for 75% to 80% of all skin cancers making BCC the most common type of cancer in humans. Squamous cell carcinoma (SCC) is the second most common type of skin cancer. Together, BCC and SCC account for 95% of all nonmelanoma skin cancers (NMSCs).
How does skin pigmentation affect risk for skin cancer?
Lightly pigmented patients are 70 times more likely to develop NMSC than patients with darkly pigmented skin. BCC is the most common type of skin cancer in Caucasians. In patients with a dark skin type, SCC is more common than BCC and tends to occur in non–sun-exposed sites. In contrast, BCC tends to occur in sun-exposed areas in dark-skinned patients with lighter complexions.
How does ultraviolet radiation contribute to carcinogenicity?
Ultraviolet (UV) light leads to the formation of pyrimidine dimers. UVB (315–290 nm) is regarded as the most carcinogenic ultraviolet radiation by causing direct damage to DNA and DNA repair mechanisms. UVA (400–315 nm) is now considered to be a co-carcinogen because it potentiates the effects of UVB.
BASAL CELL CARCINOMA
What are the risk factors for developing BCC?
The most common risk factor is UV light exposure. Patients with fair skin and little melanin are more likely to develop BCC. The incidence of BCC rises with decreasing latitude (closer to the equator). UV exposure from tanning beds and PUVA (therapeutic UV exposure) also predisposes to the development of BCC. Intermittent sun overexposure (sunburns) early in life (childhood and adolescence) is linked with the development of BCC. Other risk factors are less common such as ionizing radiation, arsenic exposure, topical nitrogen mustard use, and certain genetic syndromes.
• Basal cell nevus syndrome
• Xeroderma pigmentosum
Other than sun-exposed sites, what are the classic locations for the development of BCC?
BCC has a predilection for developing in certain locations. They may develop in an old scar (e.g., vaccination scar), in thermal burns, or at the site of a nevus sebaceous.
What are some of the clinical types of BCC?
• Superficial BCCs present as a pink to red, slightly scaly plaque. There may be areas of skin atrophy and hypopigmentation present within the plaque. Occasionally, they may develop significant subclinical spread.
• Nodular BCC presents as a skin-colored to pink papule or plaque. It may be translucent in color leading to their classic description as “pearly.” The border is often heaped and there are typically overlying telangiectases that may require magnification to visualize.
• Ulcerative BCC