One of the first steps in determining your treatment plan is establishing the stage of your Unfortunately, there is no universally accepted staging system for squamous cell skin cancer (for more on the debate over staging systems, see SCIENCE SIDEBAR). Here we present a description of squamous cell skin cancer staging that is helpful for treatment planning. It is based on risk features and the designation of disease that is local and confined vs disease that has advanced (locally, to the lymph nodes, or beyond).


Low-risk (all of the following features)

  • Tumour diameter ≤20 mm
  • Tumour thickness ≤4 mm
  • Penetrates into the dermis
  • No invasion of the nerves (perineural invasion)
  • Well differentiated or moderately differentiated histology
  • No invasion of the lymphatic channels and/or blood vessels
  • Patient with a functional immune system

High risk (any of the following)

  • Tumour diameter >20 mm to 40 mm
  • Tumour thickness >4 mm – 6 mm
  • Penetrates into the subcutaneous fat
  • Perineural invasion present; dermal only; nerve diameter <0.1 mm
  • Poorly differentiated histology
  • Invasion of the lymphatic channels and/or blood vessels
  • Tumour site: ear or lymph
  • Tumour arises within a scar or area of chronic inflammation
  • Patient immunosuppressed (eg, receiving a biologic drug, with treated HIV)

Very high risk (any of the following)

  • Tumour diameter >40 mm
  • Tumour thickness >6 mm
  • Penetrates beyond subcutaneous fat
  • Any bone invasion
  • Perineural invasion present; in a named nerve, nerve ≥ 0.1 mm, or a nerve beyond the dermis
  • High-grade histologic subtype
  • In-transit metastases (meaning between the original tumour and the lymph nodes in the region)
  • Patient with immunosuppression (eg, receiving immunosuppression for solid organ transplantation or a hematologic malignancy)

What are the challenges of locally advanced squamous cell skin cancer?

  • There is the risk of invasion of deeper layers of the skin and spread to other parts of the body. If squamous cell skin cancer grows in and around the nerves, it can cause pain, numbness, or muscle weakness
  • Advanced squamous cell skin cancer can be difficult to treat. It might require several surgeries and can be disfiguring, requiring reconstructive surgery to repair the skin/other structures
  • As mentioned previously, patients with locally advanced disease are at increased risk of death from squamous cell skin cancer as compared with patients in whom the tumour is more confined locally

When squamous cell skin cancer spreads

Approximately four percent of squamous cell skin cancers will metastasize (spread) to the regional lymph nodes or to distant sites (other parts of the body). Patients who are immunosuppressed may have a two- to three-fold higher risk of metastasis, which means the risk for metastasis can be as high as 12 percent.

Regional Squamous Cell Skin Cancer (Nodal Disease)

Regional disease is characterized by cancer that has spread to nearby lymph nodes. Lymph nodes are small, seed-shaped structures that contain clusters of immune cells. Their function is to filter the lymphatic fluid, which helps to clear waste material from the tissues and deliver white blood cells to fight infections. Lymph nodes are found throughout the body, notably in the neck, armpit, and groin. Cancer cells typically spread from the primary tumour to the nearest lymph node before traveling to other parts of the body.

How is regional disease diagnosed?

If the lymph node feels swollen or if lymph nodes are identified by imaging, then the doctor will take a sample from the lymph node for testing by:

  • fine needle aspiration, wherein a hollow thin needle is attached to a syringe to take out fluid/small amounts of tissue to examine
  • core needle biopsy, which uses a larger needle with a larger hollow centre (bore). This involves getting a small section of tissue, which will give you more information

Cancer involving the lymph nodes. The diagram shows the primary tumour as well as the affected lymph nodes.

Skin cancer on the scalp that has spread through the lymphatics to a lymph node on the head.

Yellow sunburst shows the site of the primary tumour on the neck and spread to the lung, liver, and bone.

Distant Metastatic Squamous Cell Skin Cancer

This term classifies disease that has spread to other sites in the body—either to far away lymph nodes or the lungs, brain, or other organs, resulting in distant metastasis.

Your doctor can advise you if you need imaging to look for metastatic disease. S/he may order imaging if you have certain symptoms or abnormal laboratory tests. The additional imaging may include computed tomography (CT) or positron emission tomography/computed tomography (PET-CT). It’s important to note that most patients with squamous cell skin cancer will not need a CT scan, since the risk of distant metastatic disease is only 0.4%.

Key terms:

Computed tomography (CT) is a procedure that uses a computer linked to an x-ray machine to make a series of detailed pictures of areas inside the body. The pictures are taken from different angles and are used to create three-dimensional (3-D) views of tissues and organs. A dye may be injected into a vein or swallowed to help the tissues and organs show up more clearly. A CT scan may be used to help diagnose disease, plan treatment, or find out how well treatment is working. Also called CAT scan, computed tomography scan, computerized axial tomography scan, and computerised tomography.

PET-CT is a procedure that combines the pictures from a positron emission tomography (PET) scan and a computed tomography (CT) scan. The PET and CT scans are done at the same time with the same machine. The combined scans give more detailed pictures of areas inside the body than either scan gives by itself. A PET-CT scan may be used to help diagnose disease such as cancer, plan treatment, or find out how well treatment is working. Also called positron emission tomography-computed tomography scan.

Discussing Your Pathology Report

Here are some questions you can ask your heathcare provider about your pathology report and squamous cell skin cancer staging. It might be helpful to review the previous page High-Risk Features as well as this page so you are familiar with some of the concepts/terminology.

Talking With Your Doctor About Your Biopsy Results

Do I need further treatment? Or has the squamous cell skin cancer been fully treated?
Is this a particular type of squamous cell skin cancer?
Do I have any high-risk features? If so, how many and what are they?
What is my stage? What staging system are you using?
Is my squamous cell skin cancer localised or has it spread to my lymph nodes—or beyond?
Can I please have a copy of the pathology report?
What is my prognosis? How did you establish that? Will I need further follow-up?
Do I need a referral to any other specialists (such as a medical oncologist, radiation oncologist, or head-and-neck surgeon)?