Squamous cell carcinoma (SCC)

Squamous cell carcinoma of the skin is a common form of non-melanoma skin cancer. It develops in the flat, thin squamous cells that make up the middle and outer layer of your skin.

Image credit: 123rf

Squamous cell carcinoma occurs when squamous cells in the outer layer of your skin develop errors in their DNA. Ordinarily, new cells push older cells toward your skin's surface, and the older cells die and are sloughed off. DNA errors disrupt this orderly pattern, causing cells to grow out of control, resulting in squamous cell carcinoma.

The most common cause of damage to DNA in skin cells is from ultraviolet (UV) radiation found in sunlight. Other sources of UV radiation, such as commercial tanning lamps and tanning beds, can also cause damage.

You are at highest risk of developing a squamous cell carcinoma if you:

• are older
• have pale skin and burn easily
• have spent a lot of time outdoors for work or leisure
• have a history of sunburns, sunbathing or using sun beds 
• live in a sunny climate
• have previously had a squamous cell carcinoma or other type of skin cancer
• have a condition or take medications that affect your immune system (immune suppression).

Squamous cell carcinoma of the skin most often occurs on sun-exposed skin, such as your scalp, the backs of your hands, your ears or your lips. But it can occur anywhere on your body, including inside your mouth, on your anus and on your genitals.

Squamous cell carcinomas often appear as a raised, crusty, non-healing sore.

They may also appear as a:

• flat sore with or without a scaly crust
• new sore or raised area on an existing scar or ulcer
• rough, scaly patch on your lip that may evolve to an open sore
• red sore or rough patch inside your mouth
• red, raised patch or wart-like sore on or in your anus or on your genitals.

If you notice a change to or growth on your skin, make an appointment to see your doctor straight away. Your doctor will assess the size, location and look of the growth. They will also ask you how long you have had it and whether it bleeds or itches. 

If your doctor thinks the growth may be cancer, they may take a small sample of tissue (a biopsy). The tissue sample will be sent to a laboratory and examined under a microscope. Your doctor will let you know whether the sample shows any cancer cells or not, and will recommend appropriate treatment if necessary. 

Treatment of squamous cell carcinoma depends on its type, size and location and other factors, such as your preference. 

Options include: 

• surgical removal of the cancer (this is the most common treatment method)
• freezing it with liquid nitrogen
• topical therapies (creams)
• radiotherapy
• photodynamic therapy (a specialist treatment using light to activate creams).

If you have a squamous cell carcinoma, talk with your doctor about which treatment option is best for you. Treatment has a high success rate, provided the skin cancer is found at an early stage. Your doctor may want to schedule a future appointment to check for new lesions. 

Read more about skin cancer treatment. 

Most squamous cell carcinomas can be treated and cured. However, it is possible for these types of cancers to recur or for new skin cancers to appear. 

Do the following to reduce the risk of new cancers occurring:

• Keep all follow-up appointments with your GP or skin specialist.
• Regularly check all your skin (from head to toe). If you see anything that is growing, bleeding or in any way changing, go and see your doctor straight away. See skin checks.
• Protect your skin from the sun and avoid indoor tanning. This is essential to prevent further damage, which will increase your risk of getting another skin cancer.

Ways to protect your skin

• Avoid outdoor activities when the sun is strongest – between 10am and 4pm from September to April in New Zealand.
• Wear sunscreen and lip balm daily that offer SPF 30 or higher sun protection.
• Use sunscreen that offers broad-spectrum (UVA/UVB) protection and is water resistant. 
• Apply the sunscreen and lip balm to dry skin 15 minutes before going outdoors. 
• Apply the sunscreen to every part of your body that will not be covered by clothing. Reapply it every 2 hours if you are swimming or sweating.
• Whenever possible, wear a wide-brimmed hat, long sleeves and long pants. 
• Wear sunglasses to protect the skin around your eyes. 
• Avoid getting a tan and never use a tanning bed or sun lamp. 

See also sun safety.

Squamous cell carcinoma of the skin(external link) DermNet NZ
Squamous cell carcinoma patient information sheet(external link) British Association of Dermatologists, 2022
Squamous cell carcinoma(external link) The Skin Cancer Foundation, US, 2015
Skin cancer information(external link) The Skin Cancer Foundation, US, 2015

Basal cell carcinoma | Mate pukupuku kiritai
Skin cancer
How to choose and use sunscreen
Sunburn

1. Motley RJ, Preston PW, Lawrence CM. Multi-professional guidelines for the management of the patient with primary cutaneous squamous cell carcinoma(external link) British Association of Dermatologists, UK, 2009  

Clinical practice guidelines for keratinocyte cancer(external link) Cancer Council Australia
SCC guidelines update(external link)  British Association of Dermatologists
Managing non-melanoma skin cancer in primary care – a focus on topical treatments(external link) BPAC, NZ, 2013

See our page Skin cancer for healthcare providers

Skin lesion management guidelines

If a patient presents with a suspicious lesion:

• Assess the likelihood of melanoma being present then provisionally identify the type of lesion. See skin cancer – clinicians.
• Surgical excision with histology is the first-line treatment for all skin cancer. It has the highest cure rate among available treatments. For squamous cell carcinoma the recommended margin for excision is 4mm for a well-defined low risk lesion, or 6mm for those with poor prognostic features (see below).
• Referral, according to local guidelines, to a general practitioner with a special interest (GPSI) in skin lesions, a dermatologist, a plastic surgeon or an ENT surgeon may be appropriate for patients with poor prognostic features, eg,
  • large lesions ≥20mm
  • lesions on scalp or face
  • poorly differentiated
  • lymphatic or vascular invasion
  • fibrosing (desmoplastic) subtype.
• Patients with squamous cell carcinoma in situ (intraepidermal carcinoma) may be safely managed with cryotherapy or topical treatments when excision is not appropriate because of the location of the lesion or due to cosmetic considerations.
• Topical treatments should not be considered if the diagnosis is uncertain.

Topical treatments for non-melanoma skin cancers

The Best Practice team provides a useful summary of how fluorouracil and imiquimod creams can be used as topical treatments for non-melanoma skin cancers. See full guidance: How to use fluorouracil and imiquimod for non-melanoma skin cancer in a general practice setting(external link) BPAC, NZ, 2017

Continuing professional development

Management of non-melanoma skin cancer in primary care(external link) (Goodfellow Unit, NZ, 2017)
In this video, Dr Diana North, Goodfellow GP Advisor talks with Dr Marcus Platts-Mills, Dermatology and Skin Cancer Surgery specialist, about the management of non-melanoma skin cancer in primary care.

The Skin Cancer College Australasia(external link) also provides education for medical practitioners.