Description

Basal cell carcinoma (BCC) is the most common type of skin cancer, originating from the basal cell layer of the skin appendages.

• Rarely metastasizes but is locally invasive and capable of local tissue destruction and disfigurement

Epidemiology

Most common cancer in Europe, Australia, and the United States. The most common type of skin cancer.

Incidence

• Over 2 million new cases each year in the United States; 2.5 times more common than squamous cell carcinoma (SCC)
• Highest incidence in the world is in Australia.
• White individuals have a 1 in 5 chance of developing BCC during their lifetime.
• Most common skin cancer in Asian and Hispanic individuals; second most common skin cancer in African American/black individuals (1)
• Predominant age: generally >60 years
• Predominant sex: male > female (2:1 ratio)

Prevalence
Not well established

Etiology and Pathophysiology

UV radiation induces inflammation and cyclooxygenase activation in the skin.

Genetics
Several genetic conditions increase the risk of developing BCC:

• Albinism (recessive alleles)
• Xeroderma pigmentosum (autosomal recessive)
• Bazex-Dupré-Christol syndrome (rare, X-linked dominant)
• Nevoid BCC syndrome/Gorlin syndrome (rare, autosomal dominant)
• Cytochrome P450 CYP2D6 and glutathione S-transferase detoxifying enzyme gene mutations (especially in truncal BCC, marked by clusters of BCCs and a younger age of onset)
• Mutations in the tumor suppressor gene patched, or activated mutations in smoothened, resulting in upregulation of hedgehog pathway signaling

Risk Factors

• Chronic sun exposure (UV radiation); increased susceptibility in the following phenotypes:
  • Light complexion: skin type I (burns but does not tan) and skin type II (usually burns sometimes tans)
  • Red or blond hair
  • Blue or green eyes
• Tendency to sunburn
• Male sex, although increasing risk in women due to lifestyle changes, such as tanning beds
• Previous history of nonmelanoma skin cancer
• Family history of skin cancer
• Chronic immunosuppression: transplant recipients (5 to 10 times higher incidence), patients with HIV (2 times higher incidence), or lymphomas
• Arsenic exposure
• Immunosuppression
• UV radiation and/or use of tanning devices
• Xeroderma pigmentosum

General Prevention

• Use broad-spectrum sunscreens of at least SPF 30 daily and reapply after swimming or sweating.
• Avoid overexposure to the sun. Avoid tanning beds.
• The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of visual skin examination by a clinician to screen for skin cancer in adults. The American Cancer Society recommends cancer-related checkups every 3 years in patients 20 to 39 years old and yearly in patients ≥40 years.

Commonly Associated Conditions

• Cosmetic disfigurement (head and neck most often affected)
• Loss of vision with orbital involvement
• Loss of nerve function due to perineural spread or extensive and deep invasion
• Ulcerating neoplasms are prone to infections.