What is Non-Melanoma Skin Cancer?
Non-Melanoma Skin Cancer (NMSC) comes from the transformation of normal skin keratinocytes, which are the most abundant type of cell in skin. Like melanoma, NMSC have two main environmental causes, unprotected over-exposure to the sun’s ultraviolet (UV) rays and artificial UV sources like tanning beds. The UV rays damage the DNA in the stem cells of the skin, causing them to become susceptible to becoming cancerous. Transformation of skin cells take place over many years by the accumulation of mutations and other genetic changes. This is reflected in the fact in that NMSC generally occur later in life. Skin cancer most commonly occurs in sun-exposed area of the body, especially the head, neck, and arms. Unfortunately, UV radiation might not be the only culprit for the formation of skin cancer since skin cancer can develop on skin not ordinarily exposed to sunlight.
About 1 in 5 Americans will develop skin cancer in their lifetime. Nonmelanoma skin cancer is more common among women than men and NSMC increase lifetime risk of having another cancer. The most common form of NMSC are Basal Cell Carcinoma (BCC) followed by Squamous Cell Carcinoma (SCC). Both SCC and BCC are highly treatable if caught early.
Types of NMSC
Basal Cell Carcinoma
are the most common type of skin cancer and account for ~70% of newly diagnosed cases. BCC arises in the basal stem cells mostly associated with hair follicles. BCC occurs most often on sun-exposed areas of the skin like the face, head, and neck and usually appears as a raised, pearly white, skin-colored, or pink bump on the skin. Lesions can be flat, firm, pale, or yellow and can look like a scar. They can develop as open sores that don’t heal, or that heal and come back. BCC is commonly discovered because they are fragile and might bleed after shaving or a minor injury and the sore or cut won’t heal. These skin cancers grow very slowly and rarely spread to other parts of the body but can be locally invasive and disfiguring if left untreated. Early detection and treatment of a BCC is the key to successful recovery. When found early, almost all basal cell carcinomas can be successfully removed without complication. If you notice any spot on your skin that is growing, bleeding, or changing in any way, consult with your dermatologist.
Squamous Cell Carcinoma
is a type of skin cancer that form in both the basal and squamous layers in the epidermis. They develop when keratinocyte stem cells accumulate mutations and other genetic changes that make them susceptible to becoming cancerous. SCC most commonly occur on sun-exposed areas of the body like the head, neck, arms, and back of the hands. SCC account for ~ 30% of new NMSC and for most of the death associated with NMSC. Organ transplant recipients are 200 times more likely to have multiple aggressive SCC than the general population. SCC can be found in many places on the body
including inside your mouth, the bottoms of your feet and on your genitals. They can
appear as a rough, scaly patch, wart-like growth, or a firm red nodule that
also develop in scars or chronic skin sores. They can develop as open sores that don’t heal.
Pre-cancerous and other skin conditions related to SCC include:
Actinic keratosis (solar keratosis):
are pre-cancerous lesion with rough and scaly patches that range in color from brown to pink and usually start on the face, ears, backs of the hands, and arms. These patches grow slowly and do not usually cause symptoms. Actinic keratoses are considered pre-cursors of SCC and are often treated.
Squamous cell carcinoma in situ (Bowen disease):
are considered benign tumors that precede squamous cell skin cancer and reside only in the epidermis. SCC in situ appears as reddish, scaly patches and is often treated because it can progress to SCC.
Keratoacanthoma:
dome-shaped tumors found on sun-exposed skin, grow quickly and can be hard to differentiate from SCC. They are usually treated with surgery.
Other less common types of skin cancer include:
Kaposi sarcoma:
a skin cancer that develops in the skin’s blood vessels and causes purple or red patches on the skin.
Merkel cell carcinoma:
causes shiny, firm nodules that occur on or just beneath the skin and around hair follicles. They arise from touch sensing cells in the skin.
Sebaceous gland carcinoma:
this aggressive form of skin cancer originates in the oil glands of the skin and appears as hard, painless nodules. They are most commonly found on the eyelids.
