Squamous cell carcinomas: 8 things to know about the ‘cancer of the surfaces’

Much like adenocarcinomas, squamous cell carcinomas can develop in many locations, including the skin, lungs and cervix. 

Unlike adenocarcinomas, though, squamous cell carcinomas often occur in the head and neck, such as the lips, tongue, throat or tonsils, and even the nasal cavity, sinuses, and lacrimal (or tear) ducts and glands.

So, why do squamous cell carcinomas tend to happen so often above the shoulders? And what defining characteristics make them fall into that category? To learn more, we spoke with professor and head and neck cancer surgeon Neil Gross, M.D.

What makes cancer squamous cell carcinoma?

All cancers have to start somewhere. The term “squamous” just means these started on a surface lining of the body. 

Squamous cells line the surface of the skin, as well as the interior surfaces of the mouth. This includes the tongue and throat. They stretch down from the oral cavity into the esophagus and lungs; they can be found in the cervix, anus and bladder, too. Eventually, the surface lining changes, though, and that’s where you start getting into adenocarcinomas.

Are there any features common to all squamous cell carcinomas?

They all tend to look similar under a microscope. That’s how they get classified. But they’re further sub-categorized by where they start. You can often see the differences at the molecular level. 

Cutaneous (skin) squamous cell carcinoma, for instance, has a lot of genetic mutations that are unique to cancers caused by UV exposure. This tends to make them more responsive to immunotherapy.

What are the most common places for squamous cell carcinoma to occur?

• Skin: This is by far the most common location. We see more of these every year than all of the others combined. 
• Head and neck: Squamous cell carcinomas of the head and neck include cancers of the mouth, throat and voice box. Some of these cancers, specifically the tonsil or base of the tongue, are associated with the human papillomavirus (HPV). 
• Lung: Squamous cell carcinoma of the lungs is not as common as adenocarcinoma, but it still happens a lot when you look at global statistics.

Why do so many squamous cell carcinomas happen above the shoulders?

It’s a matter of exposure. Most skin cancers are found on the head and neck because those areas are left uncovered the most, so they get the most exposure to UV radiation.

How is squamous cell carcinoma usually diagnosed?

The majority of head and neck squamous cell carcinomas are found due to a painless lump in the neck. Sometimes, patients notice these swollen lymph nodes on their own and have them examined. Other times, medical personnel find them. Either way, we perform needle biopsies to see if they’re cancerous, then work backward to determine their source. 

The remainder of squamous cell carcinomas are found because there’s an ulcerated area on the surface of something — whether it’s inside the mouth or on someone’s arm or head. These areas tend to be tender, raised, or higher than the surrounding skin, and bleed to the touch. They also don’t heal or get better, even after several weeks.

Are certain people more likely to develop squamous cell carcinoma?

Absolutely. But there are different drivers for each type. 

• Skin cancers tend to be caused by excess UV radiation exposure, whether it’s from the sun or tanning beds. 
• Lung cancer, oral cancer and larynx cancers are often connected to smoking or tobacco use. 
• Tonsil cancers and those found on the back of the tongue tend to be associated with HPV.

So, protect your skin, don’t smoke or vape, and get the HPV vaccine, if you’re eligible.

How are squamous cell carcinomas usually treated? Does it depend on the location?

Treatment is similar across all sites if it’s caught early enough. That’s the key. If cancer is small, it can often be cured with surgery alone, just by cutting it out. That's why it’s so important to talk to a doctor about any symptoms that don’t resolve within two weeks.

With more advanced cases, it gets trickier. Then, you might need to include chemotherapy or radiation therapy in someone’s treatment plan. It all depends on the cancer’s exact location, its staging and the full extent of the disease. 

What are the latest advances in the diagnosis and treatment of squamous cell carcinoma?

Proton therapy marked a significant advance when it was introduced, as it offers a more targeted approach to radiation therapy. And robotic surgery has significantly reduced treatment side effects for some of our patients with tonsil cancers and cancers at the base of the tongue. 

But right now, the most promising approaches incorporate neoadjuvant immunotherapy. This is when the patient receives immunotherapy before surgery to stimulate the immune system against the cancer before removing it. 

In one clinical trial of squamous cell carcinoma of the skin, we found that more than half of participating patients had no tumor left to remove by the time of their surgery, after just a short course of immunotherapy. So, immunotherapy is rapidly changing how we manage these tumors.

We’re also figuring out how to get a similar response from a combination of treatments, for lung and oral cavity cancers. For patients with really advanced tongue cancers, for instance, up-front surgery might require removing the entire tongue. That, of course, would severely impact their quality of life because it would profoundly affect their ability to eat and speak. 

We’re experimenting now with a combination of chemotherapy and immunotherapy before surgery, to preserve as much tissue and function as possible among these patients. Cancer treatment isn’t just about finding a cure. It’s also about preserving function and giving patients the best quality of life possible.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.