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Basal cell carcinoma

Overview

Basal cell carcinoma is a type of skin cancer. Basal cell carcinoma begins in the basal cells — a type of cell within the skin that produces new skin cells as old ones die off.

Basal cell carcinoma often appears as a slightly transparent bump on the skin, though it can take other forms. Basal cell carcinoma occurs most often on areas of the skin that are exposed to the sun, such as your head and neck.

Most basal cell carcinomas are thought to be caused by long-term exposure to ultraviolet (UV) radiation from sunlight. Avoiding the sun and using sunscreen may help protect against basal cell carcinoma.

Basal cell carcinoma

Basal cell carcinoma is a type of skin cancer that most often develops on areas of skin exposed to the sun. This photograph shows a basal cell carcinoma that affects the skin on the lower eyelid.

Symptoms

Basal cell carcinoma usually develops on sun-exposed parts of your body, especially your head and neck. This skin cancer appears less often on the trunk and legs, and basal cell carcinoma can — but rarely — occur on parts of your body usually protected from the sun such as genitals or women's breasts.

Basal cell carcinoma appears as a change in the skin, such as a growth or a sore that won't heal. These changes in the skin, or lesions, usually have one of the following characteristics:

  • A pearly white, skin-colored or pink bump that is translucent, meaning you can see a bit through the surface. Tiny blood vessels are often visible. In people with darker skin tones, the lesion would be darker but still somewhat translucent. The most common type of basal cell carcinoma, this lesion often appears on the face, ears or neck. The lesion may rupture, bleed and scab over.
  • A brown, black or blue lesion — or a lesion with dark spots — with a slightly raised, translucent border.
  • A flat, scaly, reddish patch with a raised edge is more common on the back or chest. Over time, these patches can grow quite large.
  • A white, waxy, scar-like lesion without a clearly defined border, called morpheaform basal cell carcinoma, is the least common. This lesion is easy to overlook, but it may be a sign of a particularly invasive and disfiguring cancer.

When to see a doctor

Make an appointment with your doctor if you observe changes in the appearance of your skin, such as a new growth, a change in a previous growth or a recurring sore.

Causes

Basal cell carcinoma occurs when one of the skin's basal cells develops a mutation in its DNA.

Basal cells are found at the bottom of the epidermis — the outermost layer of skin. Basal cells produce new skin cells. As new skin cells are produced, they push older cells toward the skin's surface, where the old cells die and are sloughed off.

The process of creating new skin cells is controlled by a basal cell's DNA. A mutation in the DNA causes a basal cell to multiply rapidly and continue growing when it would normally die. Eventually the accumulating abnormal cells may form a cancerous tumor — the lesion that appears on the skin.

Ultraviolet light and other causes

Much of the damage to DNA in basal cells is thought to result from ultraviolet (UV) radiation found in sunlight and in commercial tanning lamps and tanning beds. But sun exposure doesn't explain skin cancers that develop on skin not ordinarily exposed to sunlight. Other factors can contribute to the risk and development of basal cell carcinoma, and the exact cause may in some cases not be clear.

Where skin cancer develops

Skin cancer begins in the cells that make up the outer layer (epidermis) of your skin. One type of skin cancer called basal cell carcinoma begins in the basal cells, which make skin cells that continuously push older cells toward the surface. As new cells move upward, they become flattened squamous cells, where a skin cancer called squamous cell carcinoma can occur. Melanoma, another type of skin cancer, arises in the pigment cells (melanocytes).

Risk factors

Factors that increase your risk of basal cell carcinoma include:

  • Chronic sun exposure. A lot of time spent in the sun — or in commercial tanning booths — increases the risk of basal cell carcinoma. The threat is greater if you live in a sunny or high-altitude location, both of which expose you to more UV radiation. Severe sunburn, especially during childhood or adolescence, also increases your risk.
  • Radiation therapy. Radiation therapy to treat psoriasis, acne or other skin conditions may increase the risk of basal cell carcinoma at previous treatment sites on the skin.
  • Fair skin. The risk of basal cell carcinoma is higher among people who freckle or burn easily or who have very light skin, red or blond hair, or light-colored eyes.
  • Your sex. Men are more likely to develop basal cell carcinoma than women.
  • Your age. Because basal cell carcinoma often takes decades to develop, the majority of basal cell carcinomas occur after age 50.
  • A personal or family history of skin cancer. If you've had basal cell carcinoma one or more times, you have a good chance of developing it again. If you have a family history of skin cancer, you may have an increased risk of developing basal cell carcinoma.
  • Immune-suppressing drugs. Taking medications that suppress your immune system, especially after transplant surgery, significantly increases your risk of skin cancer. Basal cell carcinoma that develops in people taking immune-suppressing drugs may be more likely to recur or spread to other parts of the body.
  • Exposure to arsenic. Arsenic, a toxic metal that's found widely in the environment, increases the risk of basal cell carcinoma and other cancers. Everyone has some arsenic exposure because it occurs naturally in the soil, air and groundwater. But people who may be exposed to higher levels of arsenic include farmers, refinery workers, and people who drink contaminated well water or live near smelting plants.
  • Inherited syndromes that cause skin cancer. Certain rare genetic diseases often result in basal cell carcinoma. Nevoid basal cell carcinoma syndrome (Gorlin-Goltz syndrome) causes numerous basal cell carcinomas, as well as disorders of the skin, bones, nervous system, eyes and endocrine glands. Xeroderma pigmentosum causes an extreme sensitivity to sunlight and a high risk of skin cancer because people with this condition have little or no ability to repair damage to the skin from ultraviolet light.

Complications

Complications of basal cell carcinoma can include:

  • A risk of recurrence. Basal cell carcinomas commonly recur. Even after successful treatment, a lesion may reappear, often in the same place.
  • An increased risk of other types of skin cancer. A history of basal cell carcinoma may also increase the chance of developing other types of skin cancer, such as squamous cell carcinoma.
  • Cancer that spreads beyond the skin. Rare, aggressive forms of basal cell carcinoma can invade and destroy nearby muscles, nerves and bone. And rarely, basal cell carcinoma can spread to other areas of the body.

Diagnosis

In order to assess any growths or changes in your skin, your doctor or a specialist in skin conditions (dermatologist) will conduct a medical history and exam.

History and general exam

Your doctor will conduct a general physical exam and ask you questions about your medical history, changes in your skin, or any other signs or symptoms you've experienced.

Questions may include:

  • When did you first notice this skin growth or lesion?
  • Has it changed since you first noticed it?
  • Is the growth or lesion painful?
  • Do you have any other growths or lesions that concern you?
  • Have you had a previous skin cancer?
  • Has anyone in your family had skin cancer? What kind?
  • Do you take precautions to stay safe in the sun, such as avoiding midday sun and using sunscreen?
  • Do you examine your own skin on a regular basis?

Skin exam

Your doctor will examine not only the suspicious area on your skin but also the rest of your body for other lesions.

Skin sample for testing

Your doctor may do a skin biopsy, which involves removing a small sample of a lesion for testing in a laboratory. This will reveal whether you have skin cancer and, if so, what type of skin cancer. The type of skin biopsy you undergo will depend on the type and size of the lesion.

Treatment

A number of treatments are available for basal cell carcinoma. What treatment is best for you depends on the type, location and size of your cancer, as well as your preferences and ability to do follow-up visits. Treatment selection can also depend on whether this is a first-time or recurring basal cell carcinoma.

Surgery and related procedures

Several surgical options are available for treating basal cell carcinoma. Depending on the size and location of the removed lesion, the wound may be allowed to heal on its own, stitched closed (sutured), or covered with a skin graft, a patch of healthy skin from another site on your body.

These procedures include the following:

  • Electrodesiccation and curettage (ED&C). ED&C is generally used to remove smaller or superficial basal cell carcinomas. The surgeon removes the surface of the skin cancer with a blade or scraping instrument (curette) and then sears the base of the cancer with an electric needle to control bleeding and kill cancer cells. In a similar procedure, the base is treated by freezing it with liquid nitrogen (cryotherapy) after curettage. ED&C can leave an oozing, crusty scab that usually heals within four to six weeks.
  • Surgical excision. In this procedure, your doctor cuts out the cancerous lesion and a surrounding margin of healthy skin. The margin is examined under a microscope to be sure there are no cancer cells. This procedure is used more often with larger lesions.
  • Freezing. This involves killing cancerous cells by freezing them with liquid nitrogen (cryosurgery). It's useful for cancers that are very thin and don't extend deep into the skin. This process requires a more prolonged freezing time — longer than cryotherapy with curettage — so it must be done carefully to avoid nerve damage that can result in a loss of feeling at the site.
  • Mohs surgery. During the procedure, your doctor removes the cancer cells layer by layer, examining each layer under the microscope until no abnormal cells remain. This allows the entire growth to be removed and only a very small amount of healthy tissue. This is usually an effective treatment for recurring basal cell carcinoma, a lesion on your face, and lesions that are large, deep, fast-growing or morpheaform. For aggressive cancers, this procedure may be followed by radiation therapy.

Drugs

Drugs used to treat basal cell carcinoma include the following:

  • Topical treatments. Basal cell carcinoma that is superficial and doesn't extend very far into the skin may be treated with creams or ointments. The drugs imiquimod (Aldara) and fluorouracil (Efudex, Fluoroplex, others) are used for several weeks to treat such low-risk basal cell carcinomas.
  • Medication for advanced cancer. Basal cell carcinoma that spreads to other areas of the body (metastasizes) may be treated with vismodegib (Erivedge) or sonidegib (Odomzo). These medications may also be an option for people whose cancers haven't responded to other treatments. These medications may block molecular signals that enable basal cell carcinomas to continue growing.

Preparing for an appointment

The following information can help you prepare for an appointment.

What you can do

  • Write down your medical history, including other conditions for which you've been treated. Be sure to include any radiation therapy you may have received, even years ago.
  • Note any personal history of exposure to excessive UV light, including sunlight or tanning beds. For example, tell your doctor if you have worked as an outdoor lifeguard or spent lots of time at the beach.
  • Make a list of immediate family members who have had skin cancer, to the best of your ability. Skin cancer in a parent, grandparent, aunt, uncle or sibling is important history to share with your doctor.
  • Make a list of your medications and natural remedies. Include any prescription or over-the-counter medications you're taking, as well as all vitamins, supplements or herbal remedies.
  • Write down questions to ask your doctor. Creating your list of questions in advance can help you make the most of your time with your doctor.
  • Find a family member or friend who can join you for your appointment. Although skin cancer is usually highly treatable, just hearing the word "cancer" can make it difficult for most people to focus on what the doctor says next. Take someone along who can help take in all the information.

Questions for your doctor

Below are some basic questions to ask your doctor about basal cell carcinoma. If any additional questions occur to you during your visit, don't hesitate to ask.

  • Do I have skin cancer? What kind?
  • How is this type of skin cancer different from other types?
  • Has my cancer spread?
  • What treatment approach do you recommend?
  • What are the possible side effects of this treatment?
  • Will I have a scar after treatment?
  • Am I at risk of this condition recurring?
  • Am I at risk of other types of skin cancer?
  • How often will I need follow-up visits after I finish treatment?
  • Are my family members at risk of skin cancer?
  • Are there brochures or other printed material that I can take with me? What websites do you recommend?

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over points you want to talk about in-depth. Your doctor may ask:

  • When did you first notice this skin growth or lesion?
  • Has it grown significantly since you first found it?
  • Is the growth or lesion painful?
  • Do you have any other growths or lesions that concern you?
  • Have you had a previous skin cancer?
  • Has anyone in your family had skin cancer? What kind?
  • How much exposure to the sun or tanning beds did you have as a child and teenager?
  • How much exposure to the sun or tanning beds do you have now?
  • Are you currently taking any medications, dietary supplements or herbal remedies?
  • Have you ever received radiation therapy for a medical condition?
  • Have you ever taken medications that suppress your immune system?
  • What other significant medical conditions have you been treated for, including in your childhood?
  • Do you or did you smoke? How much?
  • Do you now have or have you ever had a job that may have exposed you to pesticides or herbicides?
  • Do you now use or have you used well water as your primary water source?
  • Do you take precautions to stay safe in the sun, such as avoiding midday sun and using sunscreen?
  • Do you examine your own skin on a regular basis?

Prevention

You may reduce your risk of basal cell carcinoma if you:

  • Avoid the midday sun. Avoid the sun when its rays are the strongest. For most places, this is between about 10 a.m. and 4 p.m. Because the sun's rays are strongest during this period, try to schedule outdoor activities for other times of the day, even in winter. You absorb UV radiation year-round, and clouds offer little protection from damaging rays.
  • Use sunscreen year-round. Choose a sunscreen that blocks both UVA and UVB types of radiation from the sun and has an SPF of at least 15. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or perspiring. The American Academy of Dermatology recommends using a broad-spectrum sunscreen with an SPF of 30 or more. Even the best sunscreen might be less effective than the SPF number on the bottle would lead you to believe if it isn't applied thoroughly or thickly enough, or if it's perspired away or washed off while swimming.
  • Wear protective clothing. Wear protective clothing. Sunscreens don't provide complete protection from UV rays, so wear tightly woven clothing that covers your arms and legs, and a broad-brimmed hat, which provides more protection than a baseball cap or visor does. Some companies also sell photoprotective clothing. Wear sunglasses that provide full protection from both UVA and UVB rays.
  • Avoid tanning beds. Tanning beds emit UV radiation, which can increase the risk of skin cancer.
  • Become familiar with your skin so that you'll notice changes. Examine your skin so that you become familiar with what your skin normally looks like. This way, you may be more likely to notice any skin changes. With the help of mirrors, check your face, neck, ears and scalp. Examine your chest and trunk, and the tops and undersides of your arms and hands. Examine both the front and back of your legs, and your feet, including the soles and the spaces between your toes. Also check your genital area, and between your buttocks. If you notice anything unusual, talk to your doctor.
  • Ask your doctor about screening. If you've already had skin cancer, you have an increased risk of a second cancer. Talk with your doctor about how often you should be screened for a recurrence.

Last updated: October 5th, 2016

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