Skin cancers are the most common type of cancers in humans. In the United States alone, over 1 million people are diagnosed with skin cancers every year.
Cancers occur when normal cells undergo a transformation and start to multiply out of control. The tumors that result can invade into adjacent structures and continue to grow unchecked if not treated. In some cases, they may spread by traveling (metastasize) into lymph nodes, or even through the blood stream to distant areas of the body. Fortunately, the most common types of skin cancer rarely spread beyond the site of the involved skin. All of the common types of skin cancer are caused in part by excessive exposure to sunlight.
Skin cancers may be classified as 1. Melanomas and 2. Nonmelanomatous skin cancers.
Both basal cell and squamous cell cancers are nonmelanomatous and are the most common types of skin cancer. They can be quite problematic and disfiguring but do not commonly spread into the lymph system or through the bloodstream. They occur most frequently in sun exposed areas of the body.
This is the third most common type of skin cancer though the incidence is increasing. The behavior and treatment of melanomas are quite different than BCC’s and SCC’s.
The skin has two main layers – the epidermis (outer layer) and dermis. Skin cancers tend to arise from the epidermis. Basal cell carcinomas arise from the deepest layer of the epidermis. Squamous cell carcinomas arise from the middle layer of the epidermis. Melanomas arise from melanocytes – cells in our skin that produce our skin pigment (melanin) and protect us from damaging effects of sun exposure.
Complexion – lighter skinned individuals have less melanin and therefore have less natural protection from the sun’s rays.
Family history – skin cancers tend to occur more frequently in some families.
Age – skin cancers happen more frequently later in life.
Sun exposure and sunburn – this is felt to be the most important risk factor. Ultraviolet light (UV) damages skin cells and can cause them to become cancerous. Sunburns, and frequent prolonged sun exposure increase the risk for skin cancers.
These usually look like a raised, smooth, pearly bump, often on the face, neck, scalp, or shoulders.
These can appear as red, scaling, thickened patch of skin, also on sun exposed areas.
Melanomas are typically brown or black, and can arise from a new mole or a mole that has changed in some way. The guideline ABCD is used to identify lesions that may be appropriate to biopsy to see if it is a cancer:
A – Asymmetry.
B – Border irregularity
C – Color is a combination of shades of brown or black.
D – Diameter – a change in size is important, and also a size greater than 6 mm
The primary treatment of all of the common skin cancers listed above is surgical removal. BCC’s and SCC’s are treated with surgical removal alone, generally. Melanomas are also treated with surgical removal but also may require examination and treatment of nearby lymph nodes. This discussion will primarily refer to the treatment of BCC’s and SCC’s
The surgical excision of BCC’s and SCC’s can be performed with a procedure called Mohs surgery. This is a technique performed by dermatologists with specialized training in Mohs surgery. The procedure is performed under local anesthesia. After the skin cancer is excised, the edges of the cancer are then examined under a microscope with a special technique. This allows the Mohs surgeon to know where any microscopic tumor cells may have been left behind. The surgeon then immediately removes additional skin and again examines the specimen under the microscope. This is repeated until all margins are “clear”, thus ensuring that all of the skin cancer is removed. This technique also minimizes the amount of normal skin that is removed with the cancer, thus resulting in less of a deformity.
The removal of the skin cancer creates a defect of skin that usually must be repaired. The size and location of the defect determine how extensive the reconstructive surgery will be. In order to obtain the best cosmetic result, a trained specialist should perform the repair.
Simple defects can simply be sutured closed, edge to edge. More complicated defects may require the use of a “local flap”. This involves the movement of skin from an adjacent area into the defect. There are several ingenious types of flap designs, which all attempt to fill the defect while creating an optimal contour and avoiding the distorting of surrounding structures (eyelid, nose, etc). Examples include bilobed flaps, rhombic flaps, rotation flaps, and cervicofacial flaps.
More extensive defects may require a two or three stage reconstruction. In some cases, an initial procedure is performed to bring tissue into the defect, while leaving a bridge of skin still attached to the original location. This is allowed to heal for a few weeks and then another operation is performed to disconnect the attachment. Examples of these “interpolated” flaps include the paramedian forehead flap, and the melolabial flap.
The most important way to prevent skin cancers is via sun protection. Wearing sunscreen (a minimum of 30 SPF) daily is important for best protection. The sunscreen should be applied 30 minutes prior to sun exposure, and should be reapplied frequently. It is also best to wear long sleeves, a wide brimmed hat, and to avoid direct sunlight, particularly between the hours of 10 AM and 3 PM.