Squamous cell carcinoma (SCC) of the skin is a common form of non-melanoma skin cancer that arises from squamous cells, which make up much of the upper layers of the skin. SCC can develop as a result of accumulated DNA damage, usually from ultraviolet (UV) radiation, and may appear on sun-exposed areas of the body.
Squamous cell carcinoma is a cancer of squamous cells — flat cells that sit just below the surface of the skin and line many body cavities. In the skin, these cells form part of the outer protective layer. When their DNA becomes damaged, often through long-term exposure to UV light, squamous cells can begin to grow in an uncontrolled way, forming a malignant tumour.
SCC is one of the most commonly diagnosed skin cancers worldwide. It differs from basal cell carcinoma (BCC) in that it has a higher risk of invading deeper tissue and, in some cases, spreading to other parts of the body if not treated promptly.
Squamous cell carcinoma accounts for a substantial proportion of non-melanoma skin cancers. In populations with high sun exposure, SCC is very common, particularly among older adults. Because non-melanoma skin cancers are often managed outside hospital settings, official statistics may under-represent the total number of cases.
SCC can occur in anyone, but several factors increase risk:
People with darker skin tones can also develop SCC, although it is less frequent and may present in less sun-exposed areas.
SCC most often appears on areas of skin that receive the most sun exposure, including:
Squamous cell carcinoma can present in several ways and may look different across individuals and skin tones. It commonly appears as:
In people with fair skin, SCC often develops on sun-exposed areas. In those with darker skin tones, SCC sometimes occurs on non-sun-exposed sites, including the genitals, inside the mouth or under the nails.
The primary cause of SCC is accumulated DNA damage within skin cells, usually from UV radiation. UV light alters the genetic material that controls normal cell growth and repair. When enough damage accumulates, the mechanisms that keep cell division controlled may fail, and malignant cells can form.
Artificial sources of UV light, such as tanning beds, also contribute to this risk. Other contributing factors include chronic inflammation or ulcers, scars from burns or injury, and certain chemical exposures.
Diagnosis starts with a focused skin examination. A healthcare professional assesses suspicious lesions based on appearance, texture, growth pattern and patient history. They also evaluate other areas of the skin for additional suspicious marks.
Most SCC cases are confined to the skin and do not require imaging. However, imaging tests such as ultrasound, CT or MRI may be used if there is concern that the cancer has extended into deeper tissue or nearby lymph nodes.
Seek assessment if you notice:
Prompt evaluation supports early diagnosis and management.
The goal of treatment is to fully remove or destroy the cancer while minimising damage to surrounding healthy tissue. Choice of treatment depends on the size, location and depth of the tumour, as well as patient health and preferences.
Your clinician will discuss potential benefits, risks and expected outcomes.
Yes. SCC can recur at the same site or elsewhere on the skin. People who have had SCC are at higher risk of developing additional skin cancers and should have regular skin checks.
When diagnosed and treated early, most cases of squamous cell carcinoma can be managed effectively and have a favourable outlook. Many remain localised and do not spread.
Prognosis depends on factors such as tumour size, depth, location, immune status and whether the cancer has spread. SCCs that have invaded deeper tissues or metastasised to lymph nodes require more intensive management and have a less favourable prognosis.
People treated for SCC often have long-term follow-up to monitor for recurrence or new cancers. Regular skin examinations help detect changes early.
Not all cases can be prevented, but the risk can be reduced by protecting the skin from UV radiation and adopting consistent sun-protective habits.
People who have had SCC or other skin cancers should have more frequent professional skin assessments.
A clinical skin assessment can help distinguish harmless changes from those requiring closer review, supporting timely intervention if necessary.
