Skin Cancer Stages

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Staging of Skin Cancer

Skin cancer staging systems are used to describe the severity of cancer, based on the size, extent of invasion, and the spread of disease to different body parts. Staging helps to determine disease prognosis and treatment strategy.

Since different skin cancers behave differently and have variable tendency to invade nearby tissue or to spread to distant body parts, they are staged differently.

skin cancer types

Basal Cell Carcinoma Stages

BCC rarely spreads to distant body parts. Fortunately, most of the cases of BCC are cured before they can spread to distant body parts. Thus, assessment of tumor spread and staging of BCC is not required. However, several prognostic factors have been described for BCC that can predict poor prognosis of the disease.

Following is the list of such high-risk factors:

  • Anatomic site and tumor size (mask area of face, genitalia, hands, and feet with any tumor size; cheeks, forehead, scalp, neck, and pretibial region with tumor size >/=1 cm; and Trunk/remaining extremities areas with tumor size >/=2 cm),
  • tumor invading deeper skin layers,
  • poorly defined borders,
  • perineural invasion,
  • extranodal extension,
  • extension to bony structures,
  • nodal disease,
  • site of prior radiotherapy,
  • immunosuppression,
  • advanced disease/aggressive growth pattern,
  • recurrent disease,
  • poor overall health,
  • comorbidity, and
  • tobacco use.

Squamous Cell Carcinoma Stages

TNM is the most commonly used system for staging squamous cell carcinoma. “T” stands for “Tumor Size”, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Numbers and/or letters after T (is, 1, 2, 3, 4, 4a, and 4b), N (0, 1, 2, 2a, 2b, 2c, 3, 3a, and 3b), and M (0 and 1) provide more details about each of these factors.

Once T, N, and M categories of a skin cancer are determined through different diagnostic techniques, this information is combined to assign an overall stage (from 0 to IV) to the disease.

Stage 0

Tis N0 M0

Carcinoma in situ or non

A primary tumor is <2 cm in size. No spread to nearby lymph nodes or distant body parts.

Stage II

T2 N0 M0

A primary tumor size may range from >/=2 cm to <4 cm. No spread to nearby lymph nodes or distant body parts.

Stage III

T3 N0 M0

A primary tumor is >/=4 cm in size with minor bone, perineural, or deeper skin layer involvement. No spread to nearby lymph nodes or distant body parts.

T1-3 N1 M0

A primary tumor size may range from <2 cm to >/=4 cm with minor bone, perineural, or deeper skin layer involvement. The disease has spread to a single ipsilateral lymph node measuring </=3 cm without any sign of extranodal extension. No spread to distant body parts.

Stage IV

T1-3 N2 M0

A primary tumor size may range from <2 cm to >/=4 cm with minor bone, perineural, or deeper skin layer involvement. The disease has spread to a single ipsilateral lymph node measuring </=3 cm with extranodal involvement; or measuring >3 cm but <6 cm without extranodal involvement; or involvement of multiple ipsilateral/ bilateral/ contralateral lymph nodes, all measuring <6 cm without extranodal involvement. No spread to distant body parts.

Any T N3 M0

A primary tumor of any size with or without invasion to nearby tissues/structures. The disease has spread to a single lymph node measuring >6 cm without extranodal involvement or involvement of single/multiple lymph nodes with extranodal involvement. No spread to distant body parts.

T4 Any N M0

A primary tumor of any size with gross cortical bone/marrow, skull base invasion and/or skull base foramen invasion. The disease might or might not have spread to nearby lymph nodes. No spread to distant body parts.

Any T Any N M1

A primary tumor of any size with or without invasion to nearby tissues/structures. The disease might or might not have spread to nearby lymph nodes. The disease has spread to distant body parts, such as the lungs, liver, etc.

Prognostic Factors for Squamous Cell Carcinoma Skin

Similar to BCC, several prognostic factors have been described for SCC that can predict poor prognosis of the disease.

Following is the list of such high-risk prognostic factors:

  • Anatomic site and tumor size combinations (mask area of face, genitalia, hands, and feet with any tumor size; cheeks, forehead, scalp, neck, and pretibial region with tumor size >/=1 cm; and Trunk/remaining extremities areas with tumor size >/=2 cm),
  • tumor invading deeper skin layers or tumors with greater thickness,
  • poorly defined borders,
  • perineural invasion,
  • extranodal extension,
  • extension to bony structures,
  • vascular involvement,
  • lymphatic involvement,
  • site of prior radiotherapy,
  • immunosuppression,
  • advanced disease/aggressive subtype/poorly differentiated cells,
  • recurrent disease,
  • poor overall health,
  • comorbidities, and
  • patients with certain genetic disorders such as albinism or xeroderma pigmentosum.

Melanoma Skin Stages

stages of malignant melanoma

TNM is the most commonly used system for staging melanoma. “T” stands for “Tumor Thickness”, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Instead of tumor size, tumor thickness or Breslow measurement is used for assessing melanoma stage, because vertical tumor thickness is considered a better indicator of the disease prognosis and the tendency of disease spread to distant body parts.

Also, ulceration status of the melanoma lesion is important and can affect disease prognosis. Numbers and/or letters after T (is, 1, 1a, 1b, 2, 2a, 2b, 3, 3a, 3b, 4a, and 4b), N (0, 1, 1a, 1b, 1c, 2a, 2b, 2c, 3, 3a, 3b, and 3c), and M (0 and 1) provide more details about each of these factors. Once T, N, and M categories of melanoma are determined, this information is combined to assign an overall stage (from 0 to IV) to the disease.

Stage 0

Tis N0 M0

Carcinoma/Melanoma in situ or non-invasive pre-cancerous lesion confined to the superficial skin layer.

Stage IA

T1 N0 M0

A primary tumor </=1 mm in thickness without ulceration. No spread to nearby lymph nodes or distant body parts.

Stage IB

T2a N0 M0

A primary tumor >1 mm but </=2 mm in thickness without ulceration. No spread to nearby lymph nodes or distant body parts.

Stage IIA

T2b/3a N0 M0

A primary tumor >1 mm but </=2 mm in thickness with ulceration or >2 mm but </=4 mm in thickness without ulceration. No spread to nearby lymph nodes or distant body parts.

Stage IIB

T3b/4a N0 M0

A primary tumor >2 mm but </=4 mm in thickness with ulceration or >4 mm in thickness without ulceration. No spread to nearby lymph nodes or distant body parts.

Stage IIC

T4b N0 M0

A primary tumor >4 mm in thickness with ulceration. No spread to nearby lymph nodes or distant body parts.

Stage IIIA

T1/2a N1a/2a M0

A primary tumor </=1 mm in thickness without ulceration or >1 mm but </=2 mm in thickness without ulceration. A microscopic disease spread to 1–3 nearby lymph nodes. No spread to distant body parts.

Stage IIIB

T0 N1b/1c M0

A primary tumor is not present, but the microscopic disease has been detected in a nearby lymph node or in lymphatic channels around the tumor or presence of satellite tumors (nearby microscopic skin involvement). No spread to distant body parts.

T1/2a N1b/1c/2b M0

A primary tumor </=1 mm in thickness without ulceration or >1 mm but </=2 mm in thickness without ulceration. A microscopic disease has been detected in a nearby lymph node or in lymphatic channels around the tumor or the presence of satellite tumors or a spread of disease to 1–3 nearby lymph nodes. No spread to distant body parts.

T2b/3a N1a‑2b M0

A primary tumor >1 mm but </=2 mm in thickness with ulceration or >2 mm but </=4 mm in thickness without ulceration. A microscopic disease has been detected in a nearby lymph node or in lymphatic channels around the tumor or the presence of satellite tumors or a spread of disease to 1–3 nearby lymph nodes. No spread to distant body parts.

Stage IIIC

T0 N2b/2c/3b/3c M0

A primary tumor is not present, but the disease has detected in 1 or more nearby lymph nodes with or without the presence of satellite tumors. No spread to distant body parts.

T1/2/3a N2c/3 M0

A primary tumor >1 mm to </=4 mm in thickness with or without ulceration. The disease has spread to 1 or more nearby lymph nodes with or without the presence of satellite tumors. No spread to distant body parts.

T3b/4a N>1 M0

A primary tumor >2 mm but </=4 mm in thickness with ulceration or >4 mm in thickness without ulceration. The disease has spread to 1 or more nearby lymph nodes with or without the presence of satellite tumors. No spread to distant body parts.

T4b N1-2 M0

A primary tumor >4 mm in thickness with ulceration. A microscopic disease has been detected in a nearby lymph node or in lymphatic channels around the tumor or the presence of satellite tumors or a spread of disease to 1–3 nearby lymph nodes. No spread to distant body parts.

Stage IIID

T4b N3 M0

A primary tumor >4 mm in thickness with ulceration. The disease has spread to 4 or more nearby lymph nodes with or without the presence of satellite tumors. No spread to distant body parts.

Stage IV

Any T Any N M1

A primary tumor of any thickness with or without ulceration. The disease might or might not have spread to nearby lymph nodes with or without the presence of satellite tumors. The disease has spread to distant body parts, for example, the skin, soft tissue including muscles, distant lymph nodes, or visceral organs, such as the lungs, liver, or brain.

Skin Cancer Staging Investigations

If a person is suspected to have skin cancer due to signs and symptoms, some investigations are required to confirm the diagnosis of the disease and in determining the stage of disease, which in turn help in selecting an appropriate treatment option.

Biopsy

skin biopsy

Biopsy samples contain a small number of cells or a tiny piece of tissue collected from the affected area with the help of a special biopsy instrument. Biopsy sample(s) are generally collected when an abnormal area(s) is observed during the physical examination indicating skin cancer.

It is very important to obtain a biopsy sample because it can establish the diagnosis of skin cancer. It can also provide other useful information about the cancerous cells, such as the type of skin cancer, the severity of cancerous changes involved (grade of cancer), and the presence of specific defective genes.

Following are common techniques used for collecting the biopsy samples from the affected area/lymph nodes:

Shave Biopsy

In shave biopsy, a biopsy sample is obtained by shaving the upper layer of the skin using a surgical blade. This technique is generally employed for early-stage disease confined to the superficial skin layer.

Punch Biopsy

In this technique, a biopsy sample containing deeper skin tissues is obtained using a tool with a round blade that cuts through all the skin layers. This technique enables biopsy of skin cancers that have invaded into nearby tissues.

Surgical biopsy

In this technique, a tissue sample from the affected site is removed via a surgical procedure. When only a part of the tumor is removed, the procedure is known as the incisional biopsy. While in the case of excisional biopsy, the whole tumor is removed surgically. The magnitude of the procedure depends upon the location and the size of the tumor.

Excisional biopsy is usually performed when the tumor is located at an accessible site and do not involve any critical structure. It usually combines both diagnosis and treatment for the skin cancer. The surgical biopsy technique may also be used to obtain a biopsy sample from an affected lymph node.

Sentinal Lymph Node Biopsy (SLNB)

In this surgical biopsy procedure, the sentinal lymph node (the first lymph node affected by cancer) along with some nearby lymph nodes are removed and checked for the presence of cancer cells. An absence of cancer is the sentinel lymph node indicates cancer has not spread to other lymph nodes.

To find a sentinel lymph node, a surgeon first injects a radioactive substance and/or a dye into the cancer tissue. The sentinel lymph node is then determined as the first node detected to have radioactivity and/or the first lymph node that take-up the dye color. Detected sentinel lymph node is then removed and tested in a laboratory for the presence of cancer cells.

Fine Needle Aspiration (FNA) Biopsy

This technique is generally used to collect a biopsy sample from an enlarged lymph node near the skin via a fine hollow needle attached to a syringe. A very small sample is usually obtained with this technique that can be tested to establish the diagnosis of the skin cancer in the suspected lymph node(s). This technique is most commonly used and very easy to perform with minimum side effects. It can also be utilized to diagnose disease progression or recurrence in patients who have received treatment.

Imaging Tests

These tests help in scanning a larger body area to assess the exact size and location of the disease and the spread of disease to distant body parts. The extent of invasion within the primary tissue affected and in the nearby tissue can also be assessed with the help of these techniques. These are primarily employed after the establishment of the pathological diagnosis to estimate the extent of disease. Also, they can be employed after treatment to evaluate the treatment efficacy and to detect any signs of disease progression/recurrence.

  • Computed tomography (CT) scan
  • Magnetic resonance imaging (MRI) scan
  • Positron emission tomography (PET) scan
  • Bone Scan

Certain blood tests may also be employed in the patients with skin cancer for the estimation of overall health, nutritional status, liver and kidney functions, and blood cells counts. These tests help in assessing whether the standard treatment like surgery, chemotherapy, or radiotherapy can be safely employed for the patient.

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