Skin cancer is the most common type of cancer and commonly develops in sun-exposed areas of skin. Skin cancers can be found on any location of the body but are most commonly diagnosed on the head and neck (ie, areas of chronic sun exposure).
The incidence is highest among people who spend a lot of time outdoors for work or recreation and is inversely related to the amount of melanin skin pigmentation; people who have light skin are most susceptible.
Skin cancers may also develop years after therapeutic radiation or exposure to carcinogens (eg, arsenic ingestion).
Over 5.4 million new cases of nonmelanoma skin cancer were diagnosed in 2012 in over 3.3 million people in the United States. (See The Skin Cancer Foundation.)
The most common forms of skin cancer are
Basal cell carcinoma Basal Cell Carcinoma Basal cell carcinoma is a superficial, slowly growing papule or nodule that derives from certain epidermal cells. Basal cell carcinomas arise from keratinocytes near the basal layer, which are... read more (approximately 80%) (1 References Skin cancer is the most common type of cancer and commonly develops in sun-exposed areas of skin. Skin cancers can be found on any location of the body but are most commonly diagnosed on the... read more )
In a 2019 nationwide study in the United States, incidences per 100,000 people were: basal cell carcinoma, 525; squamous cell carcinoma, 262; and melanoma, 17.0 (2 References Skin cancer is the most common type of cancer and commonly develops in sun-exposed areas of skin. Skin cancers can be found on any location of the body but are most commonly diagnosed on the... read more ).
The less common forms of skin cancer are
Paget disease of the breast Paget Disease of the Breast Paget disease is a rare type of carcinoma that appears as a unilateral eczematous to psoriasiform plaque of the nipple and areola. It results from extension to the epidermis of an underlying... read more or extramammary Paget disease (usually in the groin or near the anus)
Tumors of the adnexa
Squamous cell carcinoma in situ Squamous Cell Carcinoma in Situ Squamous cell carcinoma in situ is a superficial squamous cell neoplasm. Diagnosis is by biopsy. Treatment depends on the tumor’s characteristics and may involve curettage and electrodesiccation... read more (formerly called Bowen disease) is a superficial squamous cell carcinoma. Keratoacanthoma Keratoacanthoma Keratoacanthomas are round, firm, usually flesh-colored nodules with sharply sloping borders and a characteristic central crater containing keratinous material; they usually resolve spontaneously... read more may be a well-differentiated form of squamous cell carcinoma.
Initially, skin cancers are often asymptomatic. The most frequent presentation is an irregular red or pigmented lesion that does not go away. Any lesion that appears to be enlarging should be biopsied—whether tenderness, mild inflammation, crusting, or occasional bleeding is present or not. If treated early, most skin cancers are curable.
References
1. American Cancer Society: Key Statistics for Basal and Squamous Cell Skin Cancers. Accessed November 20, 2023.
2. Aggarwal P, Knabel P, Fleischer AB Jr: United States burden of melanoma and non-melanoma skin cancer from 1990 to 2019. J Am Acad Dermatol. 85(2):388-395, 2021. doi: 10.1016/j.jaad.2021.03.109
Prevention of Skin Cancer
Because many skin cancers are likely associated with ultraviolet (UV) exposure, a number of measures are recommended to limit exposure.
Sun avoidance: Seeking shade, minimizing outdoor activities between 10 AM and 4 PM (when sun's rays are strongest), and avoiding sunbathing and the use of tanning beds
Use of protective clothing: Long-sleeved shirts, pants, and broad-brimmed hats
Use of sunscreen: At least sun protection factor (SPF) 30 with broad-spectrum UVA/UVB protection, used as directed (ie, reapplied every 2 hours and after swimming or sweating); should not be used to prolong sun exposure
Current evidence is inadequate to determine whether these measures reduce incidence or mortality of melanoma; in nonmelanoma skin cancers (basal cell carcinoma Basal Cell Carcinoma Basal cell carcinoma is a superficial, slowly growing papule or nodule that derives from certain epidermal cells. Basal cell carcinomas arise from keratinocytes near the basal layer, which are... read more and squamous cell carcinoma Squamous Cell Carcinoma Squamous cell carcinoma is a malignant tumor of epidermal keratinocytes that invades the dermis; this cancer usually occurs in sun-exposed areas. Local destruction may be extensive, and metastases... read more ), sun protection does decrease the incidence of new cancers (1 Prevention reference Skin cancer is the most common type of cancer and commonly develops in sun-exposed areas of skin. Skin cancers can be found on any location of the body but are most commonly diagnosed on the... read more ).
Screening
Some professional organizations support clinical examination and self-examination to screen for skin cancer; however, the US Preventive Services Task Force has not found sufficient evidence to do so for the general population. (See also the US Preventive Services Task Force summary of recommendations for screening for skin cancer and counseling about skin cancer.)
High-risk patients, such as those taking immunosuppressants, those with a personal or strong family history of skin cancer, or those with a known, increased susceptibility to skin cancer because of specific genetic mutations or environmental exposures, should be considered for routine skin cancer surveillance.
Prevention reference
1. Green A, Williams G, Neale R, et al: Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial. Lancet 354(9180):723-729, 1999. doi: 10.1016/S0140-6736(98)12168-2
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
The Skin Cancer Foundation: Information about skin cancer facts and statistics
American Academy of Dermatology Association Skin Cancer Resource Center: Consumer-friendly information about finding, treating, and raising awareness for skin cancers