Basal Cell Carcinoma

What is Basal Cell Carcinoma? Basal Cell Carcinoma is the most common type of skin cancer, with over 2 million cases diagnosed per year in the United States. It is the cancer of basal cells which compose the lowest layer of the epidermis. Basal cell carcinoma may be diagnosed at a young age, but most occur between the ages of 40 and 70.

What are the Risk Factors for Basal Cell Carcinoma?

The risk factors for basal cell carcinoma are a combination of internal and external factors:

  • Lighter skin color is associated with a 30% lifetime risk.
  • Light eye color, freckles, and blonde or red hair.
  • Personal or family history of skin cancer or genetic conditions associated with skin cancer, such as basal cell nevus syndrome, xeroderma pigmentosum, Bazex-Dupré-Christol Syndrome, and oculocutaneous albinism.
  • Men over the age of 40 have a higher risk.
  • Exposure to ultraviolet radiation is the most significant environmental risk factor through sun damage, especially in childhood, or tanning bed use.
  • Chronic immunosuppression as seen in HIV-positive patients, organ transplant patients, and those previously treated with methotrexate.
  • Photosensitizing drugs such as tetracyclines and thiazide diuretics.
  • Ionizing radiation.
  • Exposure to carcinogenic drugs, especially arsenic.


What does Basal Cell Carcinoma look like?

Most basal cell carcinoma occurs in areas exposed to the sun, although 15% may be found on the trunk. Basal cell carcinomas have a tendency to remain localized and very few become metastatic.

Based on the features of the tumor, basal cell carcinoma is classified into main three groups:

  • Nodular- Most common type. Present as shiny, well-defined translucent papules or nodules with a thickened border and telangiectasias.
  • Superficial- Least aggressive type. Present with lesions that are pink, scaly, thin plaques that may be mistaken for eczema or psoriasis.
  • Morpheaform- Higher risk for recurrence and local invasion. Also called sclerosing basal cell carcinoma and present as flesh-colored, waxy, ulcerated plaques with ill-defined borders. Morpeheaform basal cell carcinoma may be further classified as infiltrative or micronodular subtypes.

Basal cell carcinomas that have a high risk of recurrence are associated with certain characteristics:

  • Tumors of any size found on the head and neck, hands, feet, and genitalia.
  • Tumors ≥ 20mm in diameter on trunk and extremities, excluding hands and feet.
  • Lesions with poorly defined borders.
  • Recurrent lesions.
  • Lesions in sites of prior radiation therapy.
  • Aggressive forms: morpheaform and basosqamous forms.
  • Perineural invasion.
  • Immunocompromised patients.


Treatment for Basal Cell Carcinoma

The treatment for basal cell carcinoma is primarily concentrated on local control, as the risk of metastasis is low for most subtypes. Surgical options include:

  • Surgical excision
  • Curettage and electrodesiccation
  • Mohs micrographic surgery

Nonsurgical treatment options may be used for nonsurgical candidates or those who prefer to avoid surgery:

  • Cryosurgery
  • Topical imiquimod and fluorouracil
  • Radiation therapy

Basal cell carcinomas that have a high risk of recurrence are first treated with surgery. If the patient is not a surgical candidate or fails surgical options, adjuvant radiation therapy or systemic therapy are used. Systemic treatment options include:

  • Hedgehog pathway inhibitors: vismodegib and sonidegib
  • Immune checkpoint inhibitors: cemiplimab

Source: Kim, D. P., Kus, K. J., & Ruiz, E. (2019). Basal Cell Carcinoma Review. Hematology/Oncology Clinics of North America, 33(1), 13–24.