Squamous cell carcinoma is a common type of cancer that affects the skin. In the UK, approximately 25,000 cases of skin squamous cell carcinoma are diagnosed every year. Globally, there were over 2.2 million cases of the cancer worldwide in 2021.
Is squamous cell carcinoma a type of skin cancer?
Yes. It is likely that you have heard of melanoma, which is an aggressive type of skin cancer that can be deadly if left untreated. But fewer people have heard of a different group of skin cancers, which are called non-melanoma skin cancers.
The two major types of non-melanoma skin cancer are squamous cell carcinoma, and basal cell carcinoma.
These cancers are usually slower-growing, less aggressive than melanoma, and less likely to spread around the body. But combined together, squamous cell carcinoma and basal cell carcinoma affect many more people.
In 2022, non-melanoma skin cancers were the fifth most common type of cancer worldwide.
How is squamous cell carcinoma different from basal cell carcinoma?
Basal cell carcinoma and squamous cell carcinoma can look similar, but they also differ in some important ways:
- Site of origin. Both cancers originate in the upper layer of the skin, called the epidermis. But squamous cell carcinoma grows from squamous cells, which are located in the middle and upper part of the epidermis. Basal cell carcinoma develops from basal cells, which is near the base of the epidermis.
- Growth rate. Squamous cell carcinoma can generally grow faster than basal cell carcinoma, which tends to be very slow growing.
- Potential to spread. While both cancers very rarely spread to other parts of the body, squamous cell carcinoma in the skin may be more likely to spread compared to basal cell carcinoma.
More information about squamous cells:
What are squamous cells?
Squamous cells are a type of cell that are found throughout the body. They make up a large part of the epidermis layer of our skin, and also line other organs - including our digestive tract, respiratory tract, and blood vessels.
Where can squamous cell carcinoma develop?
Squamous cell carcinoma can develop anywhere there are squamous cells in the body. We fund research into any type of squamous cell carcinoma, including oral squamous cell carcinoma - the most common form of mouth cancer, and an aggressive form of cancer called oesophageal squamous cell carcinoma (OSCC).
How does cancer develop in squamous cells?
When squamous cell carcinoma develops in the skin, it is also called cutaneous squamous cell carcinoma (cSCC). Squamous cells in the skin start out as keratinocytes. These contain keratin, which helps to keep the skin strong, and act as a protective barrier. Eventually keratinocytes move up to the surface and change shape into flatter squamous cells, replacing dead squamous skin cells at the surface. Cancer develops when the DNA in squamous cells becomes irreparably damaged, and they begin to divide out of control. Eventually, tumours are formed.
What causes squamous cell carcinoma?
Too much ultraviolet (UV) light is a major cause of damage which leads to squamous cell skin cancer. This type of light is found in sunlight and tanning booths, and squamous cell carcinoma tends to develop in areas of the head and neck that have long-term exposure to this type of light.
Other types of skin damage can also sometimes lead to squamous cell carcinoma:
- Radiation
- Burns
- Chronic wounds or ulcers
- Scars
What does squamous cell carcinoma look like?
Squamous cell skin cancer begins in the outer layer of skin that has been exposed to sunlight - usually on the face, neck, or ears, or upper or lower limbs.
The cancer can look like a raised bump or wart on the skin, with a scaly or crusty appearance. It might be a persistent red and rough-looking patch, and it may be sore and bleed, or not hurt or itch at all.
Squamous cell carcinoma tends to grow slowly, and you may only notice small changes over time. It is always worth asking your doctor if you have any worries about skin changes - most will not be cancer, but if it is, early detection and diagnosis can ensure you receive the most effective treatment, and have the greatest chance of a full cure.
What is actinic keratosis?
UV light damage can sometimes cause small, scaly, sometimes itchy patches of sun-damaged skin that are called actinic keratosis. They are not cancer, but there is a small chance that some patches may eventually turn into squamous cell carcinoma.
Estimates suggest that around 1 - 10% may become cancerous over ten years. And having these patches may also mean you have an increased risk of developing other types of skin cancer too. It is always worth asking your doctor if you think you have developed any actinic keratosis patches, or if your skin shows any other changes you are unsure about.
Is squamous cell carcinoma curable?
Squamous cell carcinoma in the skin grows slowly, and most can be cured with treatment. Many people are then free from this cancer for the rest of their life. But for a small number of people, their cancer can come back or spread to other parts of the body.
One study found that around 1 to 2% of squamous cell carcinomas in the skin may spread to another part of the body within three years of treatment. When this happens, squamous cell skin cancer can still be cured, but a more aggressive or longer course of treatment is usually needed.
Early diagnosis is an important way to increase the chance of a full cure. You are more likely to need less invasive treatment, and to be treated successfully, if the cancer is caught early.
Who is more likely to develop squamous cell carcinoma?
Some people may be more at risk of developing squamous cell carcinoma in the skin. These include:
- People who have been exposed to a lot of sun over their lifetime.
- Older adults. Squamous cell carcinoma develops slowly, and is most usually diagnosed in adults over 60 or 70 years old.
- People who have skin that is more likely to burn in the sun.
- People with a history of skin cancer.
People with a weakened immune system (immunosuppression), can also be more susceptible to developing squamous cell carcinoma in the skin. This is because their condition makes it harder for the immune system to detect and destroy damaged cells before they turn into cancer.
How is squamous cell carcinoma diagnosed?
Diagnosis of squamous cell carcinoma usually involves visual examination and lab tests. In the UK, you will be referred to a skin specialist (dermatologist) for examination. Sometimes your GP might do this by sending pictures of your skin to a specialist for investigation.
If cancer is not ruled out at this stage, then you will usually need a biopsy. This is where a small piece of the skin is taken for examination under a microscope. The doctor will do this under local anaesthetic, so it does not hurt. Sometimes the whole area of skin is taken for examination. When this happens it is called an excisional biopsy.
How is squamous cell carcinoma treated?
Minor surgery is the usual treatment for squamous cell carcinoma. But the type of surgery can depend on various factors, including the size and depth of the cancer, location on the body, and the general health of the patient.
Different types of treatment for squamous cell carcinoma can include:
Surgical excision
The tumour is removed along with a margin of healthy tissue around it. This generally involves local anaesthetic and a few stitches afterwards. Sometimes a skin graft is needed if a large amount of tissue is taken.
Curettage and cautery
This involves scraping cancer cells away and then sealing the area with heat. This type of surgery may be used for smaller, shallower types of squamous cell carcinoma.
Mohs surgery
This is a very specialised type of surgery that involves carefully removing layers of cancer cells and examining each layer under a microscope during the procedure. This technique might be used if the cancer is in a delicate location, for example on the lips, where it is important to save as much healthy skin as possible.
Non-surgical treatments:
Radiotherapy may also sometimes be used to treat squamous cell carcinoma. If the cancer has spread, the patient may need combination therapy. This could involve surgery, radiotherapy, and chemotherapy. For cancer that is more advanced, newer immunotherapy or targeted treatments may also be used.
Why is more research into squamous cell carcinoma needed?
Many people diagnosed with squamous cell carcinoma can expect to be fully cured following treatment. But for some people, their cancer has already spread by the time it is diagnosed. For others, it can come back after treatment and sadly, not everybody survives.
Innovative new immunotherapy approaches, which work by boosting our own immune system against cancer, are already helping to change this. They also bring hope for immunocompromised people, who are more likely to develop this cancer.
But we still need to understand how to make these treatments more effective for more people. We need to find new ways to stop treatment resistance developing, which is still a common issue for immunotherapies. We also need to work out better ways of predicting who is likely to benefit from these types of treatments, at an earlier stage. This is why more early-stage discovery research like ours is really needed.
What progress is Worldwide Cancer Research making?
Our Curestarters support international cancer research to answer the fundamental questions we still have about cancer and how to cure it.
By getting to the bottom of how cancer develops, and figuring out exactly how we can stop it, our researchers’ work underpins new treatments and new advances that ultimately lead to fewer lives being cut short by cancer.
And we’re already doing this for squamous cell carcinoma.
Dr Markus Schober and his team in the US have been investigating exactly how squamous cells rewire their internal programs into a state that helps them turn into cancer cells. They hope that by uncovering the molecular secrets that allow healthy cells to make the switch into becoming squamous cell carcinoma cells, they can unlock new ways to diagnose squamous cell carcinoma earlier, and even prevent it from developing in the first place.
It is vital that researchers like this, supported by cancer charities like us, are able to continue starting new discoveries that will lead to new cures. None of this would be possible without your support.
Your squamous cell carcinoma FAQs:
What is squamous cell carcinoma?
Squamous cell carcinoma is a type of non-melanoma skin cancer. It usually affects areas of the skin that are often exposed to the sun.
How common is squamous cell carcinoma?
Squamous cell carcinoma is very common, as many as 25,000 people in the UK are diagnosed with the cancer every year. In 2021, it was the fifth most common cancer globally.
Is squamous cell carcinoma caused by the sun?
Yes, exposure to ultraviolet (UV) light is the main cause of squamous cell carcinoma. UV light is found in sunlight, and also in the light used by sunbeds and tanning salons.
How is squamous cell carcinoma different from basal cell carcinoma?
Both types of cancer grow in the epidermis layer of the skin, but squamous cell carcinoma begins higher up in the epidermis compared to basal cell carcinoma. And while both cancers are relatively slow growing and cure rates are very high, squamous cell carcinoma can sometimes grow more quickly, and may be more likely to spread.
Where on the body does squamous cell carcinoma skin cancer occur most often?
Squamous cell carcinoma in the skin tends to grow in areas that are most exposed to the sun. This can be in the head, face and neck areas, as well as on the limbs.
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