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

Geriatric Considerations
Greater frequency in geriatric patients (Ages 55 to 75 years have 100 times the incidence when compared with those aged <20 years.)

Pediatric Considerations

• Rare in children, but childhood radiation treatment is contributory, as are frequent or severe sunburns
• The Centers for Disease Control and Prevention recommends against using tanning beds and lamps in their guidelines for cancer prevention in school-age children.

Epidemiology

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

• Over 2 million new cases each year in the United States; 2.5 times more common than squamous cell carcinoma (SCC) and greater than all other new cases combined
• Highest incidence in the world is in Australia
• White people have a 1 in 5 chance of developing BCC during their lifetime.
• Predominant age: generally >60 years, although incidence increasing in younger populations
• Predominant sex: male > female (2:1 ratio)

Prevalence
The prevalence not well documented in cancer registry databases due to number of patients with localized BCC tumors significantly exceeding that of patients with other cancers

Etiology and Pathophysiology

• UV radiation induces inflammation and cyclooxygenase activation in the skin.
• In chromosome 9q22, mutation of patched homolog 1 (PTCH1), a tumor-suppressor gene that inhibits the hedgehog signaling pathway
• UV-induced mutations of the tumor protein 53 (TP53), a tumor-suppressor gene
• Activation of BCL2, an antiapoptosis proto-oncogene

• Several genetic conditions increase the risk of developing BCC:
  • Albinism (recessive alleles)
  • Xeroderma pigmentosum (autosomal recessive)
  • Bazex 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 non-melanoma skin cancer
• Family history of skin cancer
• Chronic immunosuppression: transplant recipients (10 times higher incidence), patients with HIV, or lymphomas
• Arsenic exposure
• Immunosuppression
• UV radiation and/or the 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 by seeking shade between 10 AM and 4 PM and wearing wide-brimmed hats and long-sleeved shirts. 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 and older.

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.