Basal-cell carcinoma
Basal-cell carcinoma (BCC), also known as basal-cell cancer, is the most common type of skin cancer. It often appears as a painless raised area of skin, which may be shiny with small blood vessels running over it; or it may present as a raised area with ulceration. Basal-cell cancer grows slowly and can damage the tissue around it but is unlikely to spread to distant areas or to result in death.
Risk factors include exposure to ultraviolet light, having lighter skin, radiation therapy, long-term exposure to arsenic, and poor immune-system function. Exposure to UV light during childhood is particularly harmful. Tanning beds have become another common source of ultraviolet radiation. Diagnosis often depends on skin examination, confirmed by tissue biopsy.
It remains unclear whether sunscreen affects the risk of basal-cell cancer. Treatment is typically by surgical removal. This can be by simple excision if the cancer is small; otherwise Mohs surgery is generally recommended. Other options may include application of cold, topical chemotherapy, laser surgery, or the use of imiquimod. In the rare cases in which distant spread has occurred, chemotherapy or targeted therapy may be used.
Basal-cell cancer accounts for at least 32% of all cancers globally. Of skin cancers other than melanoma, about 80% are basal-cell cancers. In the United States, about 35% of white males and 25% of white females are affected by BCC at some point in their lives.
Individuals with a basal-cell carcinoma typically present with a shiny, pearly skin nodule. However, superficial basal-cell cancer can present as a red patch similar to eczema. Infiltrative or morpheaform basal-cell cancers can present as a skin thickening or scar tissue – making diagnosis difficult without using tactile sensation and a skin biopsy. It is often difficult to visually distinguish basal-cell cancer from acne scar, actinic elastosis, and recent cryodestruction inflammation.
About two thirds of basal-cell carcinomas occur on sun-exposed areas of the body. One-third occur on areas of the body that are not exposed to sunlight, emphasizing the genetic susceptibility of basal-cell cancer.
Mohs surgery
The clinical quotes for cure rate of Mohs surgery are from 97% to 99.8% after 5 years for newly diagnosed basal-cell cancer (BCC), decreasing to 94% or less for recurrent basal-cell cancer. Radiation oncologists quote cure rates from 90 to 95% for BCCs less than 1 or 2 cm, and 85 to 90% for BCCs larger than 1 or 2 cm. The Surgical excision cure rate varies from 99% for wide margins (4 to 6 mm) and small tumors, to as low as 70% for narrow margins and large tumors. Here the weakness of the procedure is histopathological processing and not the surgeon himself. The fault of the surgeon is failure to understand pathology laboratory methods, and failure to follow the standard of care for adequate surgical margin. Usually, the cure rate using standard bread loafing is very low for narrow surgical margin and a large tumor, and very high for large margins on small tumors.