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Last Updated: April 19, 2018

Basal Cell Carcinoma

Overview

Basal cell carcinoma is a type of skin cancer that occurs in the basal cells of the epidermis - the outermost layer of the skin. Basal cells constantly divide to replace dead or damaged skin cells closer to the outer surface of the epidermis. However, these cells can become cancerous when exposed to ultraviolet (UV) radiation or other factors, triggering them to proliferate uncontrollably. Basal cell carcinoma is the most common type of cancer with nearly 2.8 million Americans affected every year. 

Basal cell carcinoma is usually found on the head and neck, but can be found anywhere on the body, including the limbs. Unlike more aggressive cancers, basal cell carcinoma rarely spreads, or metastasizes, to other sites within the body. Timely treatment and removal are key interventions to avoiding deformity of the affected area, and spread into deeper tissues. This cancer is fully treatable if detected early, but the chance of reoccurrence in the same area or other areas of the body is high.

Causes and Risk Factors

Drawing of skin cross-section showing epidermis

Like all cancers, basal cell carcinoma is a result of errors, or mutations, in the DNA of affected cells.  While some mutations are harmless, others dismantle the cellular pathways that control cell proliferation. In the absence of tight controls, cells overgrow to form tumors. The main cause of DNA damage in basal cell carcinoma is prolonged exposure to UV light from the sun. UV radiation is also believed to block DNA repair proteins, further allowing the proliferation of mutant cells. The following risk factors are associated with basal cell carcinoma:

Symptoms

Basal cell carcinomas are most often found on the face, neck, and scalp; however, a physician should also examine any unusual bumps and sores in other areas of the body. A basal cell carcinoma may display the following symptoms:

Diagnosis and Treatment

In order to diagnose a basal cell carcinoma, the physician examines the affected area and removes a sample (biopsy) for additional evaluation. Once a positive diagnosis is made, the following treatment options are available:

Prevention

The best way to prevent basal cell carcinoma is by minimizing exposure to harmful radiation from the sun and other sources.

Routine self-examination of the skin for abnormal growth and sores is critical, especially for individuals with a high risk for basal cell carcinoma.

Sources

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Authored by: Tina Shahian, PhD