Squamous Cell Carcinoma: The Second Most Common Type of Skin Cancer

Squamous Cell Carcinoma (SCC) is the second most common type of skin cancer, second only to Basal Cell Carcinoma. It is so common that we see this type of skin cancer many times a day in our Sonoma County Dermatology practice.

What causes squamous cell carcinoma of the skin?

The very top upper layer of living cells in your skin is made up of squamous cells. These squamous cells (pronounced squ-A-mous) are layered to make up the epidermis.

Sun exposure causes damage to the DNA of these cells which may cause them to grow uncontrolled into a squamous cell cancer. Like all cancer cells, this uncontrolled growth ultimately will invade and damage vital structures in the body like muscle and bone.

Squamous cell carcinoma of the skin also has a small risk of spreading to lymph nodes and internal organs of the body. This is why it’s important to catch them early!

Who is at risk for squamous cell skin cancer?

• People with a lot of cumulative sun exposure tend to get SCCs.

• Some people are more prone to them than others including people with fair skin.

Did you know that the precancerous lesions that doctors freeze/burn off are often pre-squamous cell cancers?

Squamous cell skin cancers often start as “pre-cancers” called actinic keratoses. You may be familiar with the little liquid nitrogen gun that dermatologists are infamous for. What we are doing is spray-treat these pre-cancerous growths. We do this in an effort to prevent you from developing a squamous cell carcinoma.

Have you ever noticed that you usually get this treatment most often on those parts of your skin where you have had the most sun exposure over the years like your face, neck, ears and the back of our hands?

These are areas that also show the other signs of sun damage such as wrinkles, broken blood vessels, thin skin, and sun freckles.

Squamous cell skin cancers can also grow on any part of your skin, including inside the mouth, on the lips or genitals, your legs and feet, etc.

Understand that it’s not just sun exposure that causes squamous cell cancers, but sun is the biggest cause and the most preventable cause.

What are the 5 signs of squamous cell carcinoma?

1. A rough, pink bump
2. A sore that doesn’t heal
3. A scaly pink patch of skin
4. A rough growth under or next to the nails
5. A warty growth that pops up fast or grows like a horn and is tender

What is an actinic keratosis and how is it different than squamous cell carcinoma?

Squamous cell carcinoma often starts in a pre-cancerous form called an actinic keratosis. This is the most common skin problem I see in my practice of almost 35 years. It has a lot to do with my patients living in California and being outside a lot in the sun.

What is the risk of a precancerous actinic keratosis going on to be a squamous cell carcinoma?

It’s impossible to know exactly what percentage of actinic keratoses turns into cancer but one study showed that anywhere from 6-10% of actinic keratoses turn into squamous cell carcinoma eventually. If you do the math, that means that if you have 10 actinic keratoses, you could be guaranteed to get a skin cancer if you wait long enough! This is why I see our patients with actinic keratoses at least annually to do a full skin exam and treat all existing actinic keratoses.

I also teach my patients how identify these pre-cancers and skin cancers so that they know to come in if a worrisome spot appears on their skin between their appointments.

How to you detect an actinic keratosis on your own skin?

• For most people, an actinic keratosis is often easier to feel than see. These pre-cancers feel like a rough patch of skin that never becomes smooth.
• The patch may be more irritated by sunscreen or other things that sting like lemon juice.
• They may turn redder than other skin in the sun.
• They often look pink, red and scaly.
• Occasionally, they are tan or flesh colored.

How can actinic keratosis be treated?

There are a few ways to treat actinic keratoses. Most often, your dermatologist will freeze them with liquid nitrogen, particularly if there are only a few to treat at one visit. In my practice,

I also see people who have hundreds of actinic keratoses. In these cases, we can treat an area of skin that covers a larger area by prescribing medicated creams that inflame the pre-cancers to remedy them over a period of a month or two. People can use as a treatment called photodynamic therapy where a medicine is applied to the skin in the office and then “activated” by a special light. 

How to you prevent getting squamous cell carcinoma of the skin and actinic keratosis?

The best thing for reducing your risk is keeping UV rays from shining on, and entering your skin. Wear sun protective clothing, apply a broad spectrum SPF 30+ sunscreen to all exposed skin daily during daylight hours, and seek or create shade with a hat etc. 

Click her for my sun protection advice and to see the sunscreens that I and my patients use. These are patient proven sunscreens that I get to see work skin exam after skin exam on my active outdoorsy California patients.