Basal cell carcinoma is a type of skin cancer. Basal cell carcinoma begins in the skin cells called basal cells. The basal cells make new skin cells as old ones die off.

Basal cell carcinoma often looks like 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 get a lot of sun, such as the face and neck.

Most basal cell carcinomas are caused by exposure to light from the sun. Using sunscreen and other sun protection methods can help lower your chances of getting basal cell carcinoma.

Symptoms

Basal cell carcinoma usually occurs on parts of the body that get a lot of sun, especially the head and neck. Less often, basal cell carcinoma can develop on parts of the body usually protected from the sun, such as the genitals.

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 are called lesions. Lesions usually have one of the following characteristics:

• A shiny, skin-colored bump that's translucent, meaning you can see a bit through the surface. The bump can look pearly white or pink on white skin. On brown and Black skin, the bump often looks brown or glossy black. Tiny blood vessels might be visible, though they may be difficult to see on brown and Black skin. The bump may 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 patch with or without a raised edge. Over time, these patches can grow quite large.
• A white, waxy, scarlike lesion without a clearly defined border.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you see changes in the appearance of your skin, such as a new growth, a change in a previous growth or a returning sore.

Causes

Basal cell carcinoma starts in basal cells in the skin. Basal cells are found at the bottom of the outermost layer of skin, which is called the epidermis. Basal cells create new skin cells. As new skin cells form, they push older cells toward the skin's surface, where the old cells die and are sloughed off.

Most basal cell carcinomas are caused by exposure to light from the sun. The light that comes from the sun is a kind of ultraviolet light. This kind of light also can come from tanning beds and tanning lamps. Ultraviolet light contains radiation that changes the DNA inside the skin's basal cells. This can lead to basal cell carcinoma.

Not all basal cell carcinomas happen on skin that typically gets a lot of sun. This means something else also causes basal cell carcinomas. The cause is not always clear. But healthcare professionals have found some factors that increase the risk of basal cell carcinoma. These include having a weakened immune system and having a family history of skin cancer.

Basal cell carcinoma starts when the skin's basal cells develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. In healthy cells, the DNA tells the cells to grow and multiply at a set rate. The DNA also tells the cells to die at a set time.

In cancer cells, the DNA changes give different instructions. The changes tell the cancer cells to grow and multiply quickly. Cancer cells can keep living when healthy cells would die. This causes too many cells.

The cancer cells can invade and destroy healthy body tissue. In time, cancer cells can break away and spread to other parts of the body. When cancer spreads, it's called metastatic cancer. Basal cell carcinoma can spread, but this is rare. Most basal cell carcinomas do not spread.

Risk factors

Factors that increase the risk of basal cell carcinoma include:

• Chronic sun exposure. A lot of time spent in the sun or in commercial tanning beds increases the risk of basal cell carcinoma. The threat is greater if you live in a sunny or high-altitude location where ultraviolet radiation is stronger. Severe sunburns also increase your risk.
• Radiation therapy. Radiation therapy to treat acne or other skin conditions may increase the risk of basal cell carcinoma at previous treatment sites on the skin.
• Skin that sunburns easily. The risk of basal cell carcinoma is higher among people who have white skin, light-colored eyes, or red or blond hair.
• Increasing age. Basal cell carcinoma often takes decades to develop, so it's most common in older adults. But it also can affect younger adults and is becoming more common in people in their 20s and 30s.
• A personal or family history of skin cancer. If you've had basal cell carcinoma one or more times, you have a higher 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.
• Medicines to control the immune system. Medicines that work by suppressing the immune system raise the risk of basal cell carcinomas significantly. Medicines that work in this way include those used after an organ transplant to prevent rejection.
• Exposure to arsenic. Arsenic is a toxic metal found widely in the environment that increases the risk of basal cell carcinoma and other cancers. Everyone is exposed to some arsenic because it occurs naturally. But people who drink contaminated well water or work with arsenic may be exposed to higher arsenic levels.
• Inherited syndromes that cause skin cancer. Certain rare genetic diseases can increase the risk of basal cell carcinoma. These diseases include nevoid basal cell carcinoma syndrome, also called Gorlin-Goltz syndrome, and xeroderma pigmentosum.

Complications

Complications of basal cell carcinoma can include:

• A risk of recurrence. Basal cell carcinomas often return, even after successful treatment.
• An increased risk of other types of skin cancer. A history of basal cell carcinoma also may raise the chance of developing other types of skin cancer, such as squamous cell carcinoma.
• Cancer that spreads beyond the skin. Very rarely, basal cell carcinoma can spread to nearby lymph nodes and other parts of the body, such as the bones and lungs.

Prevention

Basal cell carcinoma and other skin cancers can be prevented by taking precautions. To lower the risk of skin cancer you can:

• Stay out of the sun during the middle of the day. For much of North America, the sun's rays are strongest between about 10 a.m. and 3 p.m. Plan outdoor activities at other times of the day. When outside, stay in shade as much as possible.
• Wear sunscreen year-round. Use a broad-spectrum sunscreen with an SPF of at least 30, even on cloudy days. Apply sunscreen generously. Apply again every two hours. Apply it more often if you're swimming or sweating.
• Wear protective clothing. Wear dark, tightly woven clothes that cover your arms and legs. Wear a wide-brimmed hat that shades your face and ears. Don't forget sunglasses.
• Don't use tanning beds. The lights in tanning beds give off ultraviolet light. Using tanning beds increases the risk of skin cancer.
• Check your skin often and report changes to your healthcare team. Look at your skin often for new growths. Look for changes in moles, freckles, bumps and birthmarks. Use mirrors to check your face, neck, ears and scalp.

  Look at your chest and trunk and the tops and undersides of your arms and hands. Look at the front and back of your legs and your feet. Look at the bottom of the feet and the spaces between your toes. Also check your genital area and between your buttocks.

Diagnosis

To diagnose basal cell carcinoma, your healthcare professional might start by asking questions about your health and looking at your skin.

History

Your healthcare professional will ask you questions about your medical history, changes in your skin, or any other symptoms you've noticed.

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 skin cancer before?
• Has anyone in your family had skin cancer? What kind?
• Do you take steps to stay safe in the sun, such as using sunscreen and avoiding midday sun?
• Do you look over your own skin on a regular basis?

Exam

Your healthcare professional may do an exam to check the suspicious area on your skin and look at the rest of your body for other lesions or concerns.

Skin biopsy

A biopsy is a procedure to remove a sample of tissue for testing in a lab. For basal cell carcinoma, a healthcare professional may do a skin biopsy to remove some of the concerning skin. This test may show whether you have skin cancer and tell you what kind it is if you do. The type of skin biopsy you have will depend on the type and size of the lesion.

Treatment

The goal of treatment for basal cell carcinoma is to completely remove the cancer. The best treatment for you depends on the type, location and size of your cancer, as well as your preferences and ability to do follow-up visits. Your treatment selection also can depend on whether this is a first-time or a returning basal cell carcinoma.

Surgery

Basal cell carcinoma is most often treated with surgery to remove all of the cancer and some of the healthy tissue around it.

Options might include:

• Surgical excision. During a surgical excision, a healthcare professional 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.

  Excision might be recommended for basal cell carcinomas that are less likely to return, such as those that form on the chest, back, hands and feet.

• Mohs surgery. During Mohs surgery, a surgeon removes the cancer layer by layer. The surgeon examines each layer under the microscope to look for cancer cells. This kind of surgery lets the surgeon take out the cancer without removing too much of the healthy skin around it.

  Mohs surgery might be recommended if your basal cell carcinoma has a higher risk of returning. This includes basal cell carcinomas that are large, extend deep into the skin or are located on your face.

Other treatments

Sometimes other treatments might be recommended in certain situations, such as if you're not able to undergo surgery or if you don't want to have surgery.

Other treatments include:

• Curettage and electrodessication. Curettage and electrodessication, also called C&E, involves removing the surface of the skin cancer with a scraping instrument called a curet. Then an electric needle is used to sear the base of the cancer. C&E might be an option for treating small basal cell carcinomas that are less likely to return. These basal cell carcinomas can include growths that form on the back, chest, hands and feet.
• Radiation therapy. Radiation therapy treats cancer with powerful energy beams. For basal cell carcinoma, radiation therapy might be used when surgery isn't an option.
• Freezing treatment. Freezing treatment, also called cryosurgery, involves freezing cancer cells with liquid nitrogen. It may be an option for treating skin lesions that haven't grown deep into the skin. Freezing might be done after using a scraping instrument to remove the surface of the skin cancer. Cryosurgery might be considered for treating small and thin basal cell carcinomas when surgery isn't an option.
• Topical treatments. Topical treatments, such as prescription creams and ointments, might be considered for treating small and thin basal cell carcinomas when surgery isn't an option.
• Photodynamic therapy. Photodynamic therapy is a two-stage treatment that combines light energy with a medicine called a photosensitizer. The photosensitizer kills cancerous cells when activated by light. Photodynamic therapy might be considered when surgery isn't an option.

Treatment for cancer that spreads

Very rarely, basal cell carcinoma may spread to nearby lymph nodes and other areas of the body. Additional treatment options in this situation include:

• Targeted therapy. Targeted therapy for cancer is a treatment that uses medicines that attack specific chemicals in the cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die. For basal cell carcinoma, targeted therapy may be used when the cancer is advanced or has spread to other areas of the body.

• Immunotherapy. Immunotherapy for cancer is a treatment with medicine that helps the body's immune system kill cancer cells. The immune system fights off diseases by attacking germs and other cells that shouldn't be in the body. Cancer cells survive by hiding from the immune system. Immunotherapy helps the immune system cells find and kill the cancer cells. For basal cell carcinoma, immunotherapy might be an option when cancer is advanced or has spread to other areas of the body.

Preparing for your 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 ultraviolet light, including sunlight or tanning beds. For example, tell your healthcare professional if you have worked as an outdoor lifeguard or spent a lot 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 healthcare professional.
• Make a list of your medicines and natural remedies. Include any prescription medicines or medicines you can buy without a prescription that you're taking. Be sure to also list any vitamins, supplements or herbal remedies you use.
• Write down questions to ask your healthcare professional. Creating your list of questions in advance can help you make the most of your appointment time.
• 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 to focus on what your healthcare professional 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 healthcare professional about basal cell carcinoma. If you have any other questions, 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 returning?
• 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 materials that I can take with me? What websites do you recommend?

What to expect from your doctor

Your healthcare professional is likely to ask about your symptoms and history. Be ready to answer questions such as:

• 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 medicines, dietary supplements or herbal remedies?
• Have you ever received radiation therapy for a medical condition?
• Have you ever taken medicines that suppress your immune system?
• What other significant medical conditions have you been treated for, including in your childhood?
• Do you use or have you used well water as your primary water source?
• Do you take steps to stay safe in the sun, such as using sunscreen and avoiding midday sun?
• Do you examine your own skin on a regular basis?