Basal Cell Carcinoma

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)
• 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)

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 at least 15 minutes before outdoor activity. Reapply every 2 hours, or immediately 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 aged 20 to 39 years old and yearly in patients aged ≥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.