Skin cancer occurs when skin cells start growing abnormally, causing cancerous growths. The three main types of skin cancer are basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma. Melanoma is the rarest but most dangerous form of skin cancer. Some types of lesions, such as actinic keratoses (AKs) may develop into skin cancer and should be monitored.
Almost all skin cancers start as a small, low-risk lesions, but can grow and become high-risk lesions if left untreated. However, if skin cancer is detected before it has spread to surrounding tissues, chances of a complete cure are excellent.
Skin Cancer Types
Actinic Keratoses (AKs) – Precancerous Skin Lesion
Actinic keratoses are dry, scaly patches that form on the skin after years of sun exposure. Actinic keratoses are considered precancerous and have the potential to become a type of skin cancer called squamous cell carcinoma. Therefore, your doctor will be diligent in diagnosing, treating, and monitoring actinic keratoses. Also, since actinic keratoses result from chronic sun exposure, you are at risk for other types of skin cancer.
Basal Cell Carcinoma (BCC)
Basal cell carcinoma (BCC) is a type of skin cancer that is derived from the basal cells in lowest part of the epidermis. It is the most common form of any cancer in the U.S., and accounts for 80% of all skin cancers. It appears on areas of the body that have had the most sun exposure. This includes the face, ears, scalp, back of the neck, and back of the arms and hands.
Basal cell carcinoma is relatively easy to detect. If it is found early, treatment is simple and successful. However, if left untreated, the lesion can cause a significant amount of damaged to local tissues. In rare cases, basal cell carcinoma can spread beyond the original lesion, making treatment much more difficult.
Here are a few examples of basal cell carcinomas:
Basal Cell Carcinoma: Types
- Superficial Basal Cell Carcinoma (sBCC): This type of basal cell carcinoma is usually seen on the trunk or extremities. It appears as a reddish spot or patch with a fine scale on the top. It can appear like a small patch of psoriasis. It can occasionally appear with a small erosion on the surface.
- Nodular Basal Cell Carcinoma: This is the most frequent type of basal cell carcinoma. It appears as a waxy or translucent nodule that may have fine blood vessels (capillaries) on its surface. The center may ulcerate, creating a sore that never completely heals. They may occasionally be pigmented like a mole (nevi).
- Sclerosing or morpheaform Basal Cell Carcinoma: This type of basal cell carcinoma appears like a scar with poorly defined (blurry) borders. It is usually flat with a thinning of the skin.
Basal Cell Carcinoma: Recurrence
Patients treated for basal cell carcinoma (BCC), should be seen periodically over a period of at least 2 years to make sure that the tumor is not recurring. Basal cell carcinoma recurrence usually occurs in the same area as the previous lesion.
Be sure to contact your dermatologist immediately if you discover a suspicious lesion before your follow-up appointment.
Squamous Cell Carcinoma (SCC)
Squamous cell carcinoma (SCC) is a type of skin cancer that appears on sun-damaged skin. It is found most commonly on the upper rim of the ear, the face, and the lips. Squamous cell carcinoma is derived from the skin cells (keratinocytes) that make up the top layers of the skin
About 10% of skin cancers are squamous cell carcinomas.
Nearly 250,000 American are diagnosed with squamous cell carcinoma each year. It is not as high risk of a cancer as melanoma, but it is important to detect and treat it early before it spreads to other tissues.
Squamous cell carcinoma that has not spread to other tissues is sometimes referred to as Squamous cell carcinoma in situ, or Bowen’s disease. The cure rate for squamous cell carcinoma in situ is over 95%.
Squamous Cell Carcinoma: Types
Squamous cell carcinoma can appear in a number of forms, including:
- A dry, crusted, scaly patch of skin that is red and swollen at the base
- A sore that won’t heal
- Crusted skin
- A thickened, crusty patch of skin with a raised border with a pebbly, granular base
If your skin shows any of these symptoms, consult a dermatologist or your doctor as soon as possible. Your doctor may perform a biopsy to diagnose squamous cell carcinoma. During this procedure, a portion of the lesion is removed and examined under a microscope.
Melanoma
Melanoma is a type of skin cancer. It is the most serious type of skin cancer because melanomas have a tendency to spread quickly to other parts of the body (metastasize).
Melanoma begins when melanocytes (pigment cells) gradually become more abnormal and divide without control or order. These cells can invade and destroy the normal cells around them. The abnormal cells form a growth of malignant tissue (a cancerous tumor) on the surface of the skin.
Most melanomas appear as dark growths similar to moles, but some may be skin-colored. Melanoma can begin as a as a new growth on the skin, or develop from an existing mole (nevi) that changes size, shape, feeling, or color.
Melanoma: Signs & Symptoms
Often, the first sign of melanoma is a change in the size, shape, color, or feel of an existing mole. Most melanomas have a black or blue-black area. Melanoma also may appear as a new mole. It may be black, abnormal, or “ugly looking.” In more advanced melanoma, the texture of the mole may change. For example, it may become hard or lumpy. Melanomas may feel different from regular moles. More advanced tumors may itch, ooze, or bleed. But melanomas are not usually painful.
Changes in the skin, such as a change in a mole, should be reported to the health care provider right away. The person may be referred to a dermatologist. A monthly skin self-exam is very important for people with any risk factors, but routine skin self-exams are a good idea for everyone.
Melanoma Risk Factors
No one knows the exact causes of melanoma. Doctors can seldom explain why one person gets melanoma and another does not. However, research has shown that people with certain risk factors are more likely than others to develop melanoma. Still, many people with melanoma have no known risk factors.
Studies have found the following risk factors for melanoma:
- Dysplastic nevi: Dysplastic nevi are more likely than ordinary moles to become cancerous. Dysplastic nevi are common, and many people have a few of these abnormal moles.
- Many (more than 50) ordinary moles: Having many moles increases the risk of developing melanoma.
- Fair skin: Melanoma occurs more frequently in people who have fair skin that burns or freckles easily (these people also usually have red or blond hair and blue eyes) than in people with dark skin.
- Personal history of melanoma or skin cancer: People who have been treated for melanoma have a high risk of a second melanoma. Some people develop more than two melanomas. People who had one or more of the common skin cancers (basal cell carcinoma or squamous cell carcinoma) are also at increased risk of melanoma.
- Family history: Melanoma sometimes runs in families. Having two or more close relatives who have had this disease is a risk factor. When melanoma runs in a family, all family members should be checked regularly by a doctor.
- Weakened immune system: People whose immune system is weakened by certain cancers, by drugs given following organ transplantation, or by HIV are at increased risk of developing melanoma.
- Severe, blistering sunburns: People who have had at least one severe, blistering sunburn as a child or teenager are at increased risk of melanoma.
- Ultraviolet (UV) radiation: Experts believe that much of the worldwide increase in melanoma is related to an increase in the amount of time people spend in the sun. This disease is more common in people who live in sunny climates. Artificial sources of UV radiation, such as sunlamps and tanning booths, also can damage the skin and increase the risk of melanoma.
Melanoma Stages
If the diagnosis is melanoma, the doctor needs to learn the extent, or stage, of the disease before planning treatment. Staging is a careful attempt to learn how thick the tumor is, how deeply the melanoma has invaded the skin, and whether melanoma cells have spread to nearby lymph nodes or other parts of the body.
The following stages are used to describe melanoma:
- Stage 0: In stage 0, the melanoma cells are found only in the outer layer of skin cells and have not invaded deeper tissues.
- Stage I: Melanoma in stage I is thin and has not spread to nearby lymph nodes.
- Stage II: The tumor is at least 1 millimeter thick and may be ulcerated; the melanoma cells have not spread to nearby lymph nodes.
- Stage III: The melanoma cells have spread to nearby tissues.
- Stage IV: The melanoma cells have spread to organs, lymph nodes, or skin far away from the original tumor.
- Recurrent: Recurrent disease means that the cancer has come back (recurred) after it has been treated. It may have come back in the original site or in another part of the body.
Skin Cancer Causes
Sunlight is composed of visible light, infrared radiation (which provides warmth), and ultraviolet (UV) radiation, which is carcinogenic (cancer-causing). More than 90 percent of all skin cancer is caused by long-term exposure to UV radiation.
UV radiation damages the skin’s DNA, causing a cell to behave abnormally. The body has mechanisms to repair damaged DNA but these repair mechanisms do not function normally after exposure to UV radiation. This allows the abnormal skin cell to replicate, making more cells with the same damaged DNA. This growing collection of abnormal cells is the beginning of a cancer.
The immune system can often detect and destroy cancer cells, just as it defends against infections by bacteria or viruses. However, UV radiation disrupts the immune system so that our natural defenses may not detect the cancer, allowing it to grow unchecked.
It is important to remember that a tan develops only after the skin has been damaged by UV radiation, and that this tan provides only minor protection from additional damage.
In addition to sun exposure, family history may also play a role in a small percentage of skin cancers, especially melanomas.
Skin Cancer Treatment
Diagnosing skin cancer usually requires a biopsy. A small piece of skin is removed for examination under a microscope and evaluated with other tests.
A treatment plan will be recommended based on several factors:
- The type of cancer
- The size of the cancer—treatments that may be effective for small cancers may not be optimal for larger cancers
- The extent of the cancer (localized to one area vs. spreading to surrounding tissues)
- The location of the cancer (face vs. arm)
- The number of lesions
- Your past history and family history of skin cancers
In general, the treatment plan is based on the risk of the cancer spreading to another location or growing again (recurring) in the same location. Cancers that are likely to spread or recur are treated more aggressively.
Treatment options include:
- Excision: This surgical procedure is used to treat both primary and recurrent tumors. It consists of surgically removing the tumor and an area of healthy looking skin (margin) around the tumor. In some cases, the wound does not require treatment and is allowed to heal on its own. When closure is necessary, the wound may be closed with stitches, skin from another area of the body (skin graft), or healthy skin moved from a nearby area (skin flap). After surgery, the excised tissue is examined under a microscope to see if any cancer cells were present in the skin that appeared cancer free.
- Curettage and electrodessication. This surgical procedure involves scraping the tumor with a curette (a surgical instrument shaped like a long spoon) and then using an electric needle to gently burn or “cauterize” the remaining cancer cells and a margin of normal-looking tissue. This scraping and cauterizing process is typically repeated several times to reduce the rate of recurrence, and the wound tends to heal without stitches. Curettage and electrodesiccation is best suited for treating a primary basal cell carcinoma or a small, superficial squamous cell carcinomas.
- Cryotherapy: This involves freezing the tumor with liquid nitrogen or another cold substance. The frozen cancer cells are destroyed by the freezing and slough off, allowing the underlying normal skin to heal. This May be used for actinic keratoses, basal cell carcinoma, or small, superficial squamous cell carcinomas.
- Laser surgery. Intense laser light may be used in certain cases to vaporize superficial lesions. Laser surgery does not destroy cancer cells found the deeper layers in the skin (dermis) so close follow-up is important.
- Mohs surgery is a specialized surgery often recommended for higher risk tumors, such as those that return in the same place after being previously treated. In this procedure, the tumor is removed in stages. Each portion of tissue is examined under a microscope to make sure that cancerous cells have been removed while sparing as much normal skin as possible. Mohs surgery has the highest reported five-year cure rate for basal cell carcinoma.
People with Stage III or Stage IV melanoma are often treated by a team of specialists. The team may include a dermatologist, surgeon, medical oncologist, radiation oncologist, and plastic surgeon.
Additional Skin Cancer Resources
- Skin Cancer Foundation
- Skin Cancer Net (American Academy of Dermatology)
