Squamous Cell Carcinoma of the Skin: Symptoms and Treatment
Squamous cell carcinoma (SCC) is the second most common skin cancer and is usually curable when caught early. Learn its warning signs, how fast it spreads, how dermatologists treat it, and when to get a spot checked in Canada.
Mohsen Khoddami
MD, Dermatologist
As of May 21, 2026.
Squamous cell carcinoma is one of the most frequently diagnosed cancers in Canada, and most cases trace back to years of sun exposure. The reassuring part is that when it is caught early, it is usually straightforward to treat and cure. This guide from DermaDex explains what squamous cell carcinoma looks like, how quickly it can progress, how dermatologists treat it, and when a spot is worth getting checked.
What is squamous cell carcinoma of the skin?
Short answer: Squamous cell carcinoma (SCC) is a cancer that begins in the flat, squamous cells (a type of keratinocyte) in the outer layer of the skin, called the epidermis. It is the second most common skin cancer after basal cell carcinoma (BCC), and both belong to a group called non-melanoma skin cancer.
SCC usually develops on areas that collect the most ultraviolet (UV) light over a lifetime: the face, ears, lower lip, scalp, neck, forearms, and the backs of the hands. Many tumours grow slowly and stay confined to the skin, where they are highly treatable. A smaller share can grow into deeper tissue or, less often, spread to nearby lymph nodes. The Canadian Dermatology Association (CDA) notes that finding skin cancer early makes treatment simpler and outcomes better, which is why knowing the signs matters. You can read more about the condition on the CDA squamous cell carcinoma page.
What are the early signs and symptoms of squamous cell carcinoma?
Short answer: The most common early signs are a rough, scaly red patch, a firm raised bump, or a sore that does not heal (or heals and then reopens). These usually appear on sun-exposed skin and may itch, feel tender, crust, or bleed when bumped.
SCC can look different from one person to the next, which is why any spot that is new, changing, or stubborn deserves attention. Some tumours grow out of a pre-cancerous actinic keratosis, a dry scaly patch caused by sun damage. The American Academy of Dermatology (AAD) lists several patterns worth watching for, summarized below.
| Warning sign | What it can look like |
|---|---|
| Persistent scaly patch | Rough, red or skin-coloured, may itch or feel tender |
| Firm raised bump | Dome-shaped nodule, sometimes with a central crust or dip |
| Non-healing sore | An open sore that bleeds, crusts, and will not heal within weeks |
| Wart-like growth | A raised, rough growth that may bleed when knocked |
| Changing actinic keratosis | A pre-cancerous dry, scaly spot that thickens or turns tender |
If a spot fits any of these descriptions and lasts more than a few weeks, have it examined. The AAD describes these early changes on its SCC symptoms page. Our overview of basal cell carcinoma explains how the two most common skin cancers differ.
What causes squamous cell carcinoma and who is most at risk?
Short answer: Cumulative UV radiation from sunlight and tanning beds is the main cause of SCC, because it damages the DNA in skin cells over time. People with fair skin, a history of sunburns, older age, a weakened immune system, or heavy lifetime sun exposure carry the highest risk.
UV radiation reaches the skin in two forms: UVA (ultraviolet A), which penetrates deeply and ages the skin, and UVB (ultraviolet B), which causes sunburn. Both contribute to skin cancer, according to the World Health Organization (WHO). Other risk factors documented in the medical literature include tanning bed use, prior radiation therapy, long-standing wounds or scars, certain human papillomavirus (HPV) infections, arsenic exposure, and immune suppression. Organ transplant recipients, for example, can have a sharply higher SCC risk than the general population because of the medicines that prevent organ rejection, as detailed in a StatPearls clinical reference from the U.S. National Institutes of Health (NIH), available through the NIH National Library of Medicine. The Government of Canada notes that most skin cancers are linked to UV exposure and are largely preventable.
How quickly does squamous cell carcinoma grow and spread?
Short answer: Most squamous cell carcinomas grow slowly over months and stay in the skin, where they are very treatable. A minority grow faster and invade deeper tissue, and roughly 2 to 5 percent spread beyond the original site, usually to nearby lymph nodes, most often when treatment is delayed.
The chance that an SCC will spread depends on features that dermatologists call high-risk: a tumour larger than about 2 centimetres, growth deep into the skin, location on the lip or ear, rapid enlargement, recurrence after earlier treatment, and a weakened immune system, as outlined in the NIH StatPearls reference. This is why timing matters. A small SCC removed early carries an excellent outlook, while a neglected one can become harder to treat and more likely to spread. Predicting the exact speed of any single tumour is unreliable, so prompt assessment is safer than waiting to see what happens.
How do dermatologists diagnose squamous cell carcinoma?
Short answer: Diagnosis starts with a skin examination and is confirmed with a biopsy, where a small sample of the suspicious area is removed and examined under a microscope. A biopsy is the only way to know for certain whether a spot is SCC.
During a visit, a dermatologist inspects the lesion, often with a handheld magnifier called a dermatoscope, and checks nearby lymph nodes if there is any concern about spread. If a biopsy confirms SCC, the pathology report describes the tumour's depth and how abnormal the cells look, which guides treatment. For tumours with high-risk features, imaging is sometimes ordered to check deeper structures. The AAD describes biopsy as the standard step before any treatment decision on its SCC overview page. DermaDex helps patients reach this step sooner by connecting them with certified dermatologists, which you can read about on our about page.
How is squamous cell carcinoma treated?
Short answer: Most squamous cell carcinomas are treated by surgically removing the tumour, and the great majority are cured when caught early. The best method depends on the tumour's size, location, depth, and risk features, ranging from minor in-office procedures to Mohs surgery, radiation, and, for advanced disease, immunotherapy.
| Treatment | Best suited for | What to expect |
|---|---|---|
| Surgical excision | Most localized SCCs | The tumour and a margin of healthy skin are removed and checked under a microscope |
| Mohs micrographic surgery | High-risk tumours, face, ears, lips, recurrent SCC | Tissue is removed and mapped layer by layer until margins are clear, sparing healthy skin |
| Curettage and electrodesiccation | Small, low-risk SCCs | The growth is scraped and the base sealed with an electric current |
| Cryotherapy | Select superficial or in-situ lesions | The lesion is frozen with liquid nitrogen |
| Radiation therapy | Patients who cannot have surgery, or as add-on care | Targeted radiation given over several sessions |
| Topical or systemic therapy | SCC in situ (creams) or advanced disease (drugs) | Creams such as 5-fluorouracil, or PD-1 inhibitor immunotherapy for advanced cancer |
Mohs micrographic surgery, which removes and checks tissue layer by layer, offers high cure rates for high-risk and cosmetically sensitive areas while sparing healthy skin, as the AAD explains on its SCC treatment page. For advanced SCC that has spread, newer immunotherapy drugs that block a protein called PD-1 have widened the options. Your care team will tailor the plan to your situation.
This article is educational and is not a diagnosis. Only a qualified clinician can examine your skin and recommend treatment.
How can you lower your risk of squamous cell carcinoma?
Short answer: Sun protection is the most effective way to lower SCC risk. Use broad-spectrum sunscreen with a Sun Protection Factor (SPF) of at least 30, seek shade during peak hours, wear protective clothing and a wide-brimmed hat, and avoid tanning beds entirely.
Canada's UV levels are highest from late spring through early fall, and they climb at higher altitudes and near reflective surfaces like water and snow. Health Canada advises checking the daily UV Index and taking precautions when it reaches 3 or higher, as described on its UV radiation page. The CDA recommends reapplying sunscreen every two hours and after swimming or sweating, with more guidance on its sun protection page. Regular skin self-checks help you catch changes early. For a closer look at choosing and applying sunscreen, see our sunscreen and SPF guide.
When should you see a dermatologist in Canada?
Short answer: See a clinician for any spot that bleeds, crusts, or does not heal within a few weeks, or any growth that is new, enlarging, or changing. Early assessment leads to simpler treatment and better outcomes, so do not wait for a lesion to become painful.
Access to dermatology varies across Canada, and wait times for a specialist referral can stretch for weeks or months depending on your province and region. That delay is one reason suspicious skin lesions are sometimes caught later than they should be. Medically necessary skin cancer assessments and biopsies are generally covered by provincial health plans such as the Ontario Health Insurance Plan (OHIP). DermaDex was built to shorten that gap by connecting patients across the country with certified dermatologists and artificial intelligence (AI) assisted triage, which is especially helpful in areas with limited specialty care. Your health information is handled in line with Canadian privacy law, including the Personal Health Information Protection Act (PHIPA). If you have a spot you are worried about, contact our team or speak with your family doctor, who can examine the area and arrange a biopsy or referral.
What are the most common questions about squamous cell carcinoma?
Short answer: Patients most often ask how to recognize SCC, how fast it spreads, how dangerous it is, and what it looks like at the start. The short version: learn the warning signs, act early, and get any non-healing or changing spot checked by a clinician.
What are three signs of squamous cell carcinoma?
Three common signs are a rough, scaly red patch that may itch or feel tender; a firm, raised bump or nodule, sometimes with a crusted or sunken centre; and a sore that does not heal, or heals and then reopens, often bleeding or crusting. These usually show up on sun-exposed skin such as the face, ears, lips, scalp, neck, and backs of the hands. Some SCCs grow from a pre-cancerous actinic keratosis, a dry scaly spot caused by sun damage. Any of these signs that lasts more than a few weeks should be examined, because a biopsy is the only way to confirm the diagnosis. The American Academy of Dermatology lists these patterns among the most common early warning signs.
How quickly does squamous cell skin cancer spread?
Most squamous cell carcinomas grow slowly over months and stay within the skin, where they are highly treatable. Speed varies by tumour. A minority grow faster and invade deeper tissue, and roughly 2 to 5 percent eventually spread beyond the skin, most often to nearby lymph nodes. The chance of spread rises with high-risk features: a tumour larger than about 2 centimetres, deep growth, location on the lip or ear, rapid enlargement, recurrence after earlier treatment, and a weakened immune system. Because delay raises the risk, the safest approach is to have a suspicious or non-healing spot evaluated early. An SCC removed while small carries an excellent prognosis, which is why prompt assessment matters more than trying to predict how fast a particular tumour might progress.
How serious is squamous cell skin cancer?
Squamous cell carcinoma is usually not life-threatening when found and treated early, and the great majority of cases are cured with a single procedure. It is still a real cancer that should be taken seriously, because untreated tumours can grow into deeper tissue, damage nearby structures, and, in a small share of cases, spread to lymph nodes or beyond. Seriousness depends on the tumour's size, depth, location, and your immune status. People who are immunosuppressed, such as organ transplant recipients, tend to have more aggressive disease and need closer monitoring. The practical takeaway: most SCCs are very manageable, but outcomes are best when treatment is not delayed. If you notice a non-healing or changing spot, have it checked rather than waiting to see whether it clears on its own.
What does the beginning of squamous cell carcinoma look like?
Early squamous cell carcinoma often looks unremarkable at first. It may begin as a small, rough, scaly patch that is red or skin-coloured, a persistent pink bump, or a spot that feels like a stubborn pimple or wart that will not go away. It can be tender, itch, crust over, or bleed with minor contact. Many SCCs start in an area of existing sun damage or from a pre-cancerous actinic keratosis. Because these early changes are easy to dismiss, the most reliable clue is persistence: a lesion that lasts beyond a few weeks, keeps returning, or slowly enlarges. On sun-exposed skin such as the face, ears, and hands, any such spot is worth showing to a clinician, who can perform a biopsy if needed to confirm whether it is cancer.
Sources
- Canadian Dermatology Association, Squamous Cell Carcinoma (Canadian Dermatology Association)
- American Academy of Dermatology, Squamous Cell Carcinoma: Signs and Symptoms (American Academy of Dermatology)
- American Academy of Dermatology, Squamous Cell Carcinoma: Overview (American Academy of Dermatology)
- American Academy of Dermatology, Squamous Cell Carcinoma: Diagnosis and Treatment (American Academy of Dermatology)
- World Health Organization, Ultraviolet (UV) radiation (World Health Organization)
- Cutaneous Squamous Cell Carcinoma, StatPearls (U.S. National Institutes of Health, National Library of Medicine)
- Government of Canada, Skin cancer (Public Health Agency of Canada)
- Health Canada, What is ultraviolet radiation (Health Canada)
- Canadian Dermatology Association, Sun Protection (Canadian Dermatology Association)