Basal Cell Carcinoma

Basal cell carcinoma is the most common form of skin cancer, affecting millions of people each year. While it rarely spreads to other parts of the body, early detection and treatment are essential to prevent local tissue damage and disfigurement.

Table of contents

• What is basal cell carcinoma?
• Causes and risk factors
• Signs and symptoms
• How is it diagnosed?
• Treatment options
• Prevention
• Outlook and life after treatment

What is basal cell carcinoma?

Basal cell carcinoma is a type of skin cancer that develops in the basal cells, which are found in the lowest part of the outer layer of your skin, called the epidermis^[1]. These cells are responsible for making new skin cells by dividing and copying themselves. When old skin cells die, basal cells create new ones to replace them^[3].

Basal cell carcinoma is the most common type of cancer overall and the most common type of skin cancer. In the United States alone, an estimated 3.6 million cases are diagnosed each year^[2]. The number of new cases in the United States exceeds 4 million cases annually^[3].

This cancer usually grows slowly. Most basal cell carcinomas are curable and cause minimal damage when caught and treated early^[2]. Unlike some other cancers, basal cell carcinoma rarely spreads to other parts of the body. However, if left untreated, it can grow deeper under the skin and cause significant destruction to surrounding tissues^[4].

Causes and risk factors

The main cause of basal cell carcinoma is damage to the DNA of basal cells. This damage usually happens after your skin has too much exposure to ultraviolet (UV) rays from sunlight or tanning beds^[1]. The prime factor in the development of this cancer is exposure to UV light, particularly UVB wavelengths, but UVA wavelengths can also play a role^[4].

Several factors increase your risk of developing basal cell carcinoma. People with fair or light-colored skin, a history of sun exposure, and a tendency to sunburn quickly are at highest risk^[6]. Fair-skinned people have a 50 percent risk of developing basal cell skin cancer at some point in their lives^[6].

Additional risk factors include:

• Having red or blond hair
• Having blue, green, or gray eyes
• Being older than 50 years, though it can occur in younger adults too^[3]
• Having a positive family history of basal cell carcinoma^[4]
• Experiencing blistering sunburns in childhood^[4]
• Being male, as men are at higher risk^[4]
• Use of indoor tanning salons^[4]

The cancer often results from years of accumulated sun exposure. Damage can start in childhood and may take 20 years to manifest^[6]. People who have had basal cell carcinoma once are at higher risk for developing another skin cancer in the future^[3].

Signs and symptoms

Basal cell carcinoma appears as a change in the skin, such as a growth or a sore that won’t heal^[1]. These changes usually occur on parts of the body that get a lot of sun, especially the head and neck. The most common places to find basal cell carcinoma include the face, scalp, nose, eyelids, legs, ears, and arms^[3]. Less often, it can develop on parts of the body usually protected from the sun, such as the genitals^[1].

The cancer can look quite different from one person to another^[2]. Common signs include:

• A shiny, skin-colored bump that’s slightly see-through (translucent), often on the face. On white skin, the bump may be skin-colored or pink. On brown and Black skin, the bump may be brown or glossy black and has a rolled border^[1]
• A flat, pale or red patch that looks like a scar^[2]
• Pink growths with slightly raised, rolled edges and a crushed indentation in the center^[2]
• Open sores that bleed, ooze, crust, or remain open for weeks^[2]
• Shiny bumps with tiny visible blood vessels^[3]
• Growths with a slightly elevated, rolled edge and a central indentation^[2]

The growths may be itchy or painful, and they may form ulcers that ooze clear fluid or bleed with contact^[3]. In patients with darker skin, about half of basal cell carcinomas are pigmented, meaning they are tan, black, or brown in color, and can be mistaken for a normal mole^[2].

The main warning sign is that the spot doesn’t go away on its own. Patients often mistake basal cell carcinomas for minor injuries. However, an ordinary cut or scratch will heal within a month or so. If something hasn’t healed within a month, it should be examined by a skin doctor^[6].

How is it diagnosed?

To diagnose basal cell carcinoma, your healthcare professional will start by asking questions about your health and looking at your skin^[11]. They will ask about your medical history, changes in your skin, when you first noticed the skin growth, and whether it has changed since you first noticed it^[11].

Your healthcare professional will examine the suspicious area on your skin and look at the rest of your body for other concerns^[11]. Experienced skin doctors can get a very good idea of whether a spot is basal cell carcinoma just by looking at it^[6].

However, a skin biopsy is necessary to confirm the diagnosis^[6]. This is a procedure to remove a sample of tissue for testing in a lab^[11]. During a skin biopsy, the healthcare professional removes some of the concerning skin. This test can show whether you have skin cancer and tell you what kind it is if you do^[11]. The type of skin biopsy you have will depend on the type and size of the growth^[11].

Treatment options

The goal of treatment for basal cell carcinoma is to completely remove the cancer^[11]. When detected early, most basal cell carcinomas can be treated and cured^[10]. 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^[11].

The current mainstay of treatment involves surgical methods. These are typically performed on an outpatient basis using a local pain-relieving medicine, with minimal pain^[10]. Surgery and radiation therapy remain the selected treatments for the majority of cases^[15].

Surgery

Surgery is the most common treatment for basal cell carcinoma. Several surgical options are available:

Surgical excision removes the cancer along with some normal tissue around it, called the surgical margin. This is a standard treatment for basal cell carcinoma in all risk groups^[16].

Mohs surgery removes the cancer in layers, little by little, until no cancer remains^[11]. The surgeon removes the visible tumor and a very small margin of tissue around and beneath the tumor site, then examines it in an on-site lab. This procedure is mainly done for high-risk basal cell carcinoma, especially on the face, or when cancer could not be completely removed by surgical excision^[16]. It may also be used to treat cancer that has come back^[16]. Mohs surgery offers cure rates close to 95 percent^[10].

Curettage and electrodesiccation uses a sharp tool called a curette to scrape the cancer and remove it from the body. Then the area is treated with heat or a chemical to destroy any remaining cancer cells, stop the bleeding, and seal off the wound^[16]. This is commonly used for small, low-risk basal cell carcinomas on the neck, central part of the body, arms, or legs^[16].

Cryosurgery uses extreme cold to freeze and destroy tissue. It is mainly used to treat low-risk basal cell carcinoma on the trunk of the body, arms, or legs^[16].

A skin graft or skin flap may be done to repair the skin after cancer is removed, especially if a large area of skin is removed^[11].

Radiation therapy

Radiation therapy uses high-energy rays or particles to destroy cancer cells^[16]. It is used instead of surgery when the cancer is in an area that is hard to treat, such as an eyelid or ear^[16]. Radiation therapy may also be used to treat cancer that was not completely removed by surgery^[16].

Topical therapy

Topical therapy is given as a cream or ointment that contains medicine and is applied on the skin. It may be used to treat small, superficial, or low-risk basal cell carcinoma on the neck, trunk of the body, arms, or legs^[16]. The medications that may be used include:

• The chemotherapy drug fluorouracil (also called 5-fluorouracil or 5-FU)^[16]
• The immunotherapy drug imiquimod^[16]

Topical therapy drugs are usually put on the growth once a day for several weeks^[16].

Other treatments

Photodynamic therapy uses chemicals and a special light to kill cancer cells^[10].

Laser surgery may be used in some cases^[10].

For advanced cases where surgery or radiation therapy is not possible, targeted therapy medications that inhibit a biological pathway called the Hedgehog pathway may be used^[15].

Prevention

The best way to prevent basal cell carcinoma is to limit sun exposure and protect your skin from UV rays^[1]. Here are important steps you can take:

• Stay out of the sun and sit in the shade when possible
• Try to avoid the sun between 10:00 am and 4:00 pm (11 am and 3 pm in the UK)^[8]
• Don’t sunbathe or use tanning beds^[8]
• Wear protective clothing, such as long-sleeved shirts, pants, and hats with broad brims^[8]
• Use sunscreen with at least 30 sun protection factor (SPF) and 4 or 5 stars for UVA protection^[8]
• Apply sunscreen generously and reapply every 2 hours and after swimming or sweating^[8]
• Wear sunglasses that give 100% UV protection^[8]

Using sunscreen and other sun protection methods can help lower your chances of getting basal cell carcinoma^[1]. However, no sunscreen can provide 100% protection, so using sunscreen should be combined with shade and clothing for continued protection^[8].

Outlook and life after treatment

Treatment to remove cancer from your skin leads to a positive outlook^[3]. Basal cell carcinoma spreads very slowly and very rarely will spread to other parts of the body^[6]. Unlike other cancers, basal cell carcinoma hardly ever spreads to other parts of the body or causes death^[8].

However, if not treated, basal cell carcinoma can continue to grow deeper under the skin and cause significant destruction to surrounding tissues^[6]. For example, an untreated basal cell carcinoma on the face can grow into the bones and, over time, directly into the brain^[6].

After treatment, it’s important to keep an eye on your skin. When you’ve had skin cancer, you are more at risk of developing another skin cancer^[25]. Be aware of what your skin normally looks like and see your doctor if you notice any skin changes or possible symptoms of skin cancer^[25]. Also see your doctor if there are any changes in the site where you had your original skin cancer^[25].

Most basal cell carcinomas are treated successfully, and it’s rare for early stage skin cancers to come back^[25]. Regular follow-up care and continued sun protection are essential for maintaining your health after treatment.