Keratinocyte Skin Cells and Cancer

Keratinocytes are the most common type of skin cells. They make keratin, a protein that provides strength to skin, hair, and nails. These cells form in the deep basal-cell layer of the skin, and take about a month to reach the surface.

It is normal for many of these cells to die off in the process. But it's also possible for their cell division to go awry, leading to what are sometimes called "keratinocyte cancers." This includes two types of non-melanoma skin cancers: basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC).

Because BCC is at work in most keratinocyte cancer cases, this article focuses primarily on the causes of BCC, as well as symptoms that suggest it may be time to call your healthcare provider. It also discusses the link to sun exposure and why this type of cancer is on the rise as people age.

Basal Cell Carcinoma

Basal cell carcinoma is the far more common of this skin cancer type. BCC accounts for some 80% of these cancers, though they rarely cause death. The other 20% are cSCC.

Symptoms of Basal Cell Carcinoma

BCCs usually develop on sun-exposed parts of your body, especially your head and neck. A much smaller number occur on the torso and legs. Yet BCCs also may occur on parts of your body that are rarely exposed to sunlight.

A more general warning sign of skin cancer comes as a sore that won't heal, or that repeatedly bleeds and scabs over. In people with darker skin, this type of cancer may look brown or black. But BCC may also appear as:

• A pearly white or waxy bump, often with visible blood vessels, on your face, ears, or neck. It may bleed and develop a crust.
• A flat, scaly, brown or flesh-colored patch on your back or chest. Over time, these patches can grow quite large.
• More rarely, a white, waxy scar. This type of BCC is easy to overlook, but it may be a sign of a particularly invasive and disfiguring cancer called morpheaform BCC.

Causes of Basal Cell Carcinoma

BCC occurs when one of the basal cells of the epidermis develops a mutation, or change, in its DNA. The process of creating new skin cells is controlled by a basal cell's DNA. A mutation in the DNA may cause a basal cell to multiply fast and continue growing when it would normally die. Eventually, the abnormal cells add up and may form a cancerous tumor.

Most BCCs are linked to long-term exposure to and damage from ultraviolet (UV) radiation. Avoiding the sun and using sunscreen may help protect against this skin cancer.This UV radiation also comes from commercial tanning lamps and tanning beds.

But sun exposure doesn't explain skin cancers that develop on skin not ordinarily exposed to sunlight. This suggests that other factors may contribute to your risk of skin cancer. They may include exposure to toxic substances, or having another medical condition that weakens your immune system.

Cutaneous Squamous Cell Carcinoma

After BCC, cutaneous squamous cell carcinoma (cSCC) is the second most common kind of skin cancer. Both are of the keratinocyte type.

Though cSCC occurs less often, it may have more serious outcomes, including death. In a small percentage of people with cSCC, the cancer will metastasize (spread) and roughly 70% of that small subset will die, according to one 2019 study.

As with other skin cancers, cases are on the rise in aging populations. It's thought that early exposure to UV light, in childhood and youth, contributes to the development of BCC and cSCC.

Annual screenings are important if you've had a previous diagnosis of either type of skin cancer. Be sure to tell your healthcare provider if you have a personal history or family history of skin cancer.

Summary

There are two primary types of skin cancer that arise from keratinocytes, the most common type of skin cells. Basal cell carcinoma accounts for the vast majority of them. Cutaneous squamous cell carcinoma accounts for just one of every five cases but it is the more dangerous of the two.

The single greatest risk known to date is exposure to UV light from the sun or artificial sources. Limiting this UV exposure may reduce the risk of getting one of these keratinocyte cancers.

A Word From Verywell

If you've noticed skin changes, or symptoms like sores that won't heal, it may be time to find out why. Make an appointment with your healthcare provider if you have any signs or symptoms that worry you.