Types of skin cancer: How they’re diagnosed and treated

What are the different types of skin cancer? How are they usually diagnosed? What do they look like? And how are they treated? 

Below are the answers to these and other common skin cancer questions you might have.

Basal cell carcinoma is the most common cancer

Basal cell carcinoma isn’t only the most common type of skin cancer. It’s also the most common cancer, period. 

Fortunately, it also tends to be one of the least aggressive, and normally only requires surgical removal to treat it. These cancers tend to grow pretty slowly, too, so when we see one that’s so large it can’t be easily cut off, it’s usually because someone left it there for a really long time. We do see some unusual cases here at MD Anderson, but it’s still rare for patients to need additional treatment.

Basal cell carcinomas are primarily caused by excess UV light exposure. But they’re also more likely to develop in skin that’s been treated with radiation therapy. They’re usually pink in color and translucent — almost pearly — in appearance. They’re typically diagnosed when patients have a skin screening, but sometimes patients will notice something unusual on their own and come in to have it checked out.

Squamous cell carcinoma: the second most common skin cancer type

Squamous cell carcinoma is the second most common type of skin cancer diagnosed each year. In terms of aggression, it falls somewhere between basal cell carcinoma and melanoma. Like basal cell carcinoma, it can be red or pink in color. The difference is that squamous cell carcinoma is normally scaly and “hyperkeratotic” — or rough to the touch, due to a build-up of hard, dead skin.

This type of skin cancer is another one that’s caused by sun damage. But certain types of leukemia can also increase patients’ chances of developing squamous cell carcinoma. And certain targeted therapies, immunotherapies and chemotherapies — or even the immunosuppressant drugs used after a stem cell transplant — can make patients more likely to develop it. 

To be clear, people who’ve undergone these treatments and don’t already have sun-damaged skin aren’t just going to start growing a bunch of squamous cell carcinoma. But what doctors have noticed is that patients who were already prone to develop squamous cell carcinoma tend to get more of it when they’re on these drugs.

Squamous cell carcinoma is typically found during skin cancer screening exams or noticed by patients. It’s usually treated the same way as basal cell carcinoma: by cutting the cancer out. But in cases where a patient is immunocompromised, or the cancer has spread or is showing aggressive tendencies — such as wrapping itself around nearby nerves or blood vessels — we also might treat it with immunotherapy or radiation therapy.

Right now, we’re exploring whether immunotherapy can treat basal and squamous cell carcinomas through clinical trials. I consider this a huge breakthrough, because previously, we didn’t have many systemic treatments to offer these patients. Chemotherapy was not very effective, and for a small subset of patients who had really aggressive tumors, we didn’t have anything great to give them.

These clinical trials are still ongoing, of course, so it’s too early to say for sure, but it appears that we might have something to give those patients in the future. The results have been very promising so far. And the prospect of having more therapy options to offer our patients is really exciting.

Melanoma is the type of skin cancer with the biggest genetic component

Melanoma is a type of skin cancer that develops when melanocytes — the cells that generate the pigment called melanin — grow out of control. Of the three types of skin cancer I’ve mentioned, melanoma has the most potential to become aggressive. But when we catch it early, it’s not.

Many cases of melanoma are diagnosed when a patient notices a black, dark or multi-colored mole or lesion on their skin and asks a doctor to look at it. But it’s still shocking to me how many people come to MD Anderson for something else and find out that they also have melanoma. 

Melanoma doesn’t always develop in areas that get a lot of sun exposure. Sometimes, it appears on the palms of the hands, in between the toes or even on the scalp, hidden by thick hair. 

That’s one reason why many of my patients tell me they keep coming back to MD Anderson for their annual skin exams: because we look EVERYWHERE.

Melanoma causes and treatment

Melanoma can be caused by environmental risk factors, such as sun exposure. But out of all the skin cancers, melanomas also have the largest genetic component. Doctors have found that people with the BRCA2 mutation, for instance, are at increased risk of developing melanoma. So, patients who carry that gene are automatically flagged to get regular skin exams as a part of their follow-up care.

The treatment of melanoma depends on its stage. For stages 0 and Ia, we’d normally just remove it surgically. Any stage higher than that might require us to remove sentinel lymph nodes, too, or cut out more tissue around the tumor to ensure we get clean margins.

We don’t use chemotherapy much to treat melanoma now, though. Instead, it’s all targeted therapy, radiation therapy and immunotherapy. In fact, ipilimumab — the very first immune checkpoint inhibitor — was approved by the Food and Drug Administration (FDA) initially for the treatment of melanoma.

Actinic keratosis is the precursor of squamous cell carcinoma

Actinic keratosis is worth mentioning because this skin condition is the most common thing we see in our clinics. 

Actinic keratosis is not cancer yet. But it’s considered a precursor — or “pre-cancer” — of squamous cell carcinoma. It usually appears as a rough spot on the skin that won’t go away. We can treat it in the office, by freezing it off with liquid nitrogen. 

See a dermatologist if a skin change doesn’t go away

With all of these skin conditions, it’s really important to catch them early. That’s when they’re typically easier to treat. So, if something unusual on your skin doesn’t resolve on its own within a month or so, go see a dermatologist.

Also, do everything you can to reduce your chances of getting skin cancer. That means staying away from tanning beds, applying sunscreen properly, wearing hats and other protective clothing outside, and staying out of the sun between 10 a.m. and 4 p.m., when its UV rays are strongest. With skin cancer, a few simple prevention steps can make a big difference in reducing your overall risk.

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