Skin cancer is the abnormal or uncontrollable growth of skin cells. It is a frequent and locally destructive malignant (cancerous) growth of the skin which begins in the cells lining the membrane separating the outermost skin from deeper skin layers. Often, skin cancer arises when the skin is repeatedly exposed to the sun, but it also may occur in areas of the skin that are not normally exposed to sunlight. Skin cancer may appear on the face and nose, back of the neck, ears and scalp, and less commonly on the chest, back or extremities. The risk of skin cancer is reduced by avoiding or minimizing exposure to ultraviolet (UV) radiation, but frequently checking the skin for any suspicious changes can help early detection and successful treat the cancer.
There are 3 major types of skin cancer
1. Basal cell carcinoma
This is the most common and highly treatable skin cancer, with more than 1 million news cases diagnosed in the U.S. annually. Basal cell carcinoma begins in the outer skin layer (epidermis). There are many different forms of basal cell carcinoma including:
(a) the superficial type that is least worrisome
(b) the nodular type that is most common
(c) the morpheaform type that lacks well-defined borders and grows into surrounding tissues
Basal cell carcinoma responds well to radiotherapy, but chemotherapy, surgery and cryosurgery also may be used.
2. Squamous cell carcinoma
Accounting for about 20 percent of all skin cancers, squamous cell carcinoma also begins in the epidermis and behaves much like basal cell carcinoma. It has a minimal but significant chance of spreading to distant areas, but responds well to radiotherapy. It also can be treated using surgery, cryotherapy, chemotherapy and photodynamic therapy.
Originating in the pigment-producing cells (melanocytes) of the skin, melanoma is a rare but the most serious type of skin cancer. It may spread to the lymph nodes of the neck and head and result in serious health problems. It is usually treated first by surgery followed by radiotherapy, chemotherapy and biologic therapy. Other less common forms of skin cancer include merkel cell carcinoma, cutaneous lymphoma, Kaposi sarcoma, demartofibrosarcoma and atypical fibroxanthoma.
How common is skin cancer?
Skin cancer is the most common cancer in the U.S. with 1 in 5 Americans developing the cancer in the course of a lifetime. In fact, over the last 3 decades, more Americans have had more skin cancer than all the other types of cancer combined. Every year, more than 5.4 million non-melanoma skin cancers are treated in more than 3.3 million Americans, with new annual cases of skin cancer exceeding the total number of new prostate, breast, colon and lung cancers. About 40-50 percent of Americans who live beyond age 65 will have either basal cell or squamous cell carcinoma at least once.
Causes of skin cancer
Skin cancer is believed to arise when mutations occur in the DNA of skin cells, resulting in uncontrollable and erratic growth. Abnormal multiplication of skin cells causes a mass to form on the skin. Most commonly, skin cancer starts in the topmost layer of the skin (epidermis). The epidermis is the outer protective layer of the skin, providing cover for the skin cells continually shed off by the skin.
There are three main types of cells in the epidermis: basal cells, squamous cells and melanocytes. Squamous cells are found just below the outermost skin surface and act as the inner lining of the skin. Basal cells sit just underneath the squamous cells and produce new skin cells, while melanocytes are found in the lower portion of the epidermis and produce melanin, the pigment that gives normal color to the skin. These cells will grow normally unless some factors come into play and change the way they behave.
The factors include:
- Ultraviolet light: Exposure to UV light from tanning beds or directly from the sun may cause damage in the DNA of skin cells. The damage may be worse near the equator or in areas of high elevation where sunlight is more intense. Excessive sun exposure without protecting the skin with clothing or sunscreen increases the risk of skin cancer. Likewise, a history of sunburn in early years of life increases the risk of skin cancer later in life.
- Fair skin: While any person can get skin cancer regardless of skin color, those with less pigment (melanin) in the skin have less protection and suffer more damage from UV radiation. People with red or blond hair and light-colored eyes tend to sunburn or freckle easily and are more likely to have skin cancer than those with darker skin.
- Moles: Abnormal moles (dysplastic nevi) increase the risk of skin cancer. Such moles are generally larger and irregular than normal moles and easily become cancerous.
- Weakened immunity: When the immune system is chronically suppressed due to HIV/AIDS, cancer or certain drugs, the risk of developing skin cancer increases significantly. Elderly patients are at greater risk of having skin cancer than younger ones.
- Personal or family history of skin cancer: If you have previously developed skin cancer, you are at a high risk of having the cancer again. Likewise, having a parent or sibling with skin cancer increases the risk of getting the cancer.
- Precancerous skin lesions: Certain skin lesions called actinic keratoses, which appear as rough and scaly brown, dark or pink patches on the head, face and hands of fair-skinned individuals, increase the risk of skin cancer.
- Exposure to radiation: Those who are exposed to ionizing radiation (such as X-rays) or chemicals such as arsenic, have increased risk of getting skin cancer. Sexually acquired wart virus also may increase the risk of skin cancer.
Symptoms of skin cancer
The symptoms of skin cancer primarily depend on the type of cancer. For instance, basal cell carcinoma shows very few and less troublesome symptoms while squamous cell carcinoma may be painful. Skin cancer also tends to be slow-growing, but forming a skin bump that bleeds, crusts, oozes or fails to heal after minor trauma.
1. Symptoms of basal cell carcinoma
(a) Appearance of a red, shiny pink, pearly, waxy or translucent bump on the skin.
(b) Flat, brown, pink or flesh-colored scar-like lesions with crusted centers and raised borders.
(c) A yellow, white or waxy area on the skin, which has poorly defined borders.
(d) A raised reddish skin patch that may itch or crust, but is rarely painful.
2. Symptoms of squamous cell carcinoma
(a) Firm, red skin nodules.
(b) Persistent flat lesions with scaly, crusted surfaces.
(c) Open sores that persist for weeks.
(d) Wart-like skin growths
(e) Raised growths with rough surfaces, poor borders and indented center.
3. Symptoms of melanoma
(a) Large brownish spots with darker speckles.
(b) Moles that change their size, color and feel frequently, or that bleed.
(c) Small lesions with irregular borders and parts that appear white, red, blue or blue-black.
(d) Dark lesions on the soles, palms, toes, fingertips or the mucous membranes lining the nose, mouth, anus or vagina.
4. Symptoms of less common skin cancers
Some important but less common skin cancers include Kaposi sarcoma, merkel cell carcinoma and sebaceous gland carcinoma. Kaposi sarcoma is rare but occurs in people with weakened immunity such as those with HIV/AIDS. It develops in blood vessels of the skin and causes purple or red patches on the mucous membranes or skin. Merkel cell carcinoma occurs in the neck, trunk and head. It causes firm, shiny nodules on or below the skin and in the hair follicles. Sebaceous gland carcinoma is a rare but aggressive cancer that begins in the oil glands of the skin and appears as hard, painless skin nodules. When they occur on the eyelid, they tend to be mistaken for other eyelid problems.
Diagnosis of skin cancer
Skin cancer is diagnosed in two ways:
- Skin examination: A dermatologist will examine the skin for any changes that may indicate cancer. In most cases, skin appearance alone will help to diagnose skin cancer.
- Skin biopsy: When skin cancer is suspected, the dermatologist will remove a sample of the suspicious-looking skin and send to the lab for testing. The area under the suspected tumor is numbed with a local anesthetic (such as lidocaine) and a small piece of skin is sliced away. A biopsy is a reliable way of onfirming skin cancer.
Treatment for skin cancer
There are several treatment options for skin cancer. In determining the best option for you, the doctor will consider your age, overall health, preferences and the type, location and size of the cancer. The treatment also will depend on how much the cancer has spread elsewhere in the body. Common treatment options for skin cancer include surgery, freezing, chemotherapy, scraping and radiotherapy.
- Mohs micrographic surgery: A visible skin tumor and the skin layer around it is removed using a curette (sharp, ring-shaped device) or scalpel. The remaining layer of the skin is then sampled and examined for tumor cells. If tumor is detected, the procedure is repeated until the remaining tissue is completely tumor-free. Mohs surgery spares healthy tissue, minimizes recurrence, and delivers the highest overall cure rate. It is however expensive and more complicated and so it is rarely used.
- Surgical excision: During the procedure, the area around the skin tumor is numbed using a local anesthetic before the tumor and a thin tissue surrounding it are removed. The wound is closed with stitches (sutures) while the excised tissue is sent to the lab for examination to confirm if all cancerous cells have been removed. The excision may be repeated if it is discovered that the tumor has not been fully removed. The cure rate of surgical excision exceeds 90 percent while the scar left behind is cosmetically acceptable.
- Electrodessication and curettage (EDC): For a small skin lesion, the skin area is numbed using a local anesthetic and the tumor is repeatedly scraped off using a curette (sharp-ring-shaped device). The tumor site is then burned with heat produced by an electrocautery needle in order to destroy residual tumor and control bleeding. This procedure is easy, fast and inexpensive, but the scar left behind may be somewhat unsightly.
- Cryosurgery: Skin tumors can be destroyed by freezing them with liquid nitrogen applied with a spray device or a cotton-tipped applicator. This procedure does not require localized anesthesia as there is no cutting or bleeding. Cryosurgery may require several sessions to destroy all the malignant cells. After the procedure, the tumor becomes scabbed and crusted and then falls off within weeks of the treatment. It is inexpensive, easy to administer and suitable for patients with anesthesia intolerance or bleeding disorders.
- Chemotherapy (topical medications): To treat superficial skin cancers, certain topical gels, creams and solutions can be used. For example, imiquimod (Aldara) and 5-fluorouracil (5-FU) are safe and effective topical drugs for treating skin cancer. Chemotherapy will not cause side effects in many patients, but some will have skin inflammation, redness and irritation.
- Photodynamic therapy (PDT): This treatment involves applying a chemical agent that reacts with light to a tumor. The abnormal cells will then take up the chemical agent and get selectively destroyed after exposure to light. Commonly used chemical agents are topical methyl aminolevulinate (MAL) and 5-aminolevulinic acid (5-ALA), which are effective in treating skin cancer of the scalp and the face.
- External beam radiotherapy: High-energy beams (like X-rays or protons) are directed at the skin tumor. After a series of 10-15 treatment sessions with radiation being delivered to the tumor and the small tissue surrounding it, the cancer is cured, its growth slowed or its symptoms relieved. Radiotherapy is useful in patients where surgery is inappropriate (such as the elderly and those with poor immunity) and for tumors that are difficult to remove surgically.
To cope with and recover from skin cancer after treatment:
- Discuss potential side effects of treatment with your doctor and learn ways of dealing with them.
- Inform the doctor of any supplements or medications you are taking. The doctor will determine whether they are safe to use during and after treatment.
- Follow your doctor’s instructions carefully. Whenever you are not sure of anything, ask your doctor.
- Get enough rest during treatment.
- Eat a healthy, well-balanced diet. Speak with your doctor or a dietitian if you have trouble eating.
- Take good care of your skin. Avoid exposure to the sun and only use ointments and lotions approved by your doctor.
- Seek help from your family, friends, support groups and your cancer treatment team.