Squamous cell cancer (SCC) is a type of skin cancer. To determine the severity of SCC, doctors use a staging system. There are five stages in total, ranging from 0–4.

SCC stages describe the size of the primary tumor and how much it has spread relative to where it first started.

While SCC most commonly affects skin exposed to the sun’s ultraviolet (UV) rays, it can also occur in the mouth, airways, lungs, digestive tract, and urinary tract. As such, the exact symptoms and staging criteria can vary depending on the location.

Read on to learn more about the stages of SCC, their symptoms, treatment options, and prognosis.

A doctor examining squamous cell carcinoma on a patient's back using a magnifying device.Share on Pinterest
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At stage 0, atypical cells are only present in the top layer of the skin or tissue. It has not become cancer yet and has not spread anywhere else. Doctors sometimes call this stage “carcinoma in situ” or Bowen disease.

Stage 0 cancer may or may not be visible. If it is, it may manifest differently depending on the area. For example:

  • the skin or nails may have changes in color or texture
  • the mouth may have white or red patches
  • the eyes may feel itchy or have a burning sensation

Another precancerous condition that can lead to SCC is actinic keratosis. It appears as a rough, scaly patch of skin that may be pink, red, brown, or the same color as the surrounding skin.

At stage 1, cancerous cells are present in the skin or other tissues. The tumor is small and has not spread to any lymph nodes.

Lymph nodes are part of the lymphatic system. Once cancer spreads to them, it can travel to other areas of the body.

At this stage, SCC of the skin or mouth may be visible as a lesion or lump. If it is in the mouth, it will be under 2 centimeters (cm) wide and may bleed easily.

Stage 2 SCC may be present in deeper layers of the skin, but it still has not spread to nearby lymph nodes. If it is in the mouth, the tumor is 2–4 cm.

External SCC may cause more discomfort or pain than earlier stages and may be more noticeable.

If SCC is inside the esophagus, it has spread beyond the inner layers of the tissue to the outer layers. In the latest substage, it may reach some lymph nodes.

At stage 3, SCC is larger and may have spread to nearby lymph nodes. The cancer may also grow further into the tissue and other nearby structures, such as bones, muscles, or other organs.

In skin cancer, stage 3 SCC is more than 4 cm, or under 4 cm but present in a single lymph node that is 3 cm or less. The tumor may grow into the fat tissue beneath the skin or in the space around a nerve.

Oral SCC is also a similar size at stage 3. It may affect swallowing if it is near the base of the tongue, in the throat, or in the esophagus. A person may be able to feel a lump in their throat.

Stage 4 SCC can be any size. At this stage, it is also present in:

  • one or more lymph nodes
  • bone or bone marrow
  • other organs, such as the lungs or brain

This may cause significant discomfort or pain, depending on where the cancer is. It may also cause a range of other symptoms, such as:

  • fatigue
  • unintentional weight loss
  • night sweats
  • wheezing or coughing
  • difficulty or pain when swallowing
  • changes in personality or brain function

This is not a comprehensive list of symptoms.

For stage 0, 1, and 2 SCC, early and aggressive treatment to remove cancerous or precancerous cells is the main treatment. This stops the cancer from having a chance to spread.

Treatment may involve:

  • Mohs surgery: This is the preferred type of surgery for skin SCC. During Mohs surgery, a surgeon removes a layer of skin and surrounding tissue, and then immediately looks at it under a microscope to determine whether any cancer cells remain. They repeat the process until there are only noncancerous cells in the sample.
  • Other surgeries: Another approach to surgery is removing the tissue and sending it to a laboratory offsite. Testing results reveal whether the edges of the tissue are cancerous or noncancerous.
  • Electrosurgery: Electrosurgery, or curettage and electrodesiccation, involves scraping off the cancer cells with a curette and searing the skin to kill the cancerous cells. A doctor may need to repeat this treatment several times.
  • Cryotherapy: A doctor freezes and destroys cancerous cells and tissues using liquid nitrogen. This may also require repeat treatments to ensure all cancerous cells are gone.

For SCC that has spread beyond the initial tumor to lymph nodes or other structures, doctors may recommend the above treatments in combination with systemic therapies. These therapies may include:

  • Radiation: This involves aiming high energy X-rays at part of the body to kill cancer cells. Radiation therapy usually requires treatments multiple times per week for several weeks.
  • Photodynamic therapy: This involves using a substance sensitive to UV light, applying it to an area, and then exposing it to intense light. This burns cancerous cells.
  • Medications: The Food and Drug Administration (FDA) has approved a few medications for SCC of the skin. Doctors can prescribe them for aggressive or advanced cancer. The medications include cemiplimab-rwlc (Libtayo) and pembrolizumab (Keytruda). Both are a form of immunotherapy.

These treatments may also work for people who cannot have surgery.

It is uncommon for SCC of the skin to be fatal. Because it is usually visible, people can detect it early and get prompt treatment.

Unless a person has a compromised immune system, there is also a relatively low risk of SCC spreading. Only about 2% of cases metastasize.

This does not mean SCC is not dangerous, though. The more advanced SCC becomes before doctors diagnose it, the more opportunity it has to spread. Advanced skin SCC has a 5-year survival rate below 40%.

SCC inside the body can also be harder to detect and treat. For this reason, anyone with any unexplained or concerning symptoms is encouraged to speak with a doctor as soon as possible.

The stages of squamous cell carcinoma (SCC) range from 0–4. At stage 0, there are atypical cells that are not yet cancerous, which may or may not be visible. By stage 4, the cancer may be large and will have spread to other organs.

In its early stages, SCC is highly treatable. In later stages, the cancer can be more difficult or more complex to treat, particularly if it affects other structures or is deeper inside the body.