SkinCancerNet Article
Staging: The First Step in Treating Skin Cancer

When skin cancer is diagnosed, your dermatologist needs to know if the cancer is confined to the original tumor or if it has spread. This is known as the extent, or stage, of the cancer. The process used to find the stage is called “staging.” Identifying the stage allows the physician to:

  • Plan appropriate treatment

  • Provide a prognosis (survival rate and risk of recurrence)

  • Give the patient information that will be needed should participation in a clinical trial be considered

Nonmelanoma Skin Cancer
The original biopsy is frequently all that is needed to stage basal cell carcinoma and squamous cell carcinoma — the two most common forms of nonmelanoma skin cancer. Basal cell carcinoma very rarely spreads. Squamous cell carcinoma is somewhat more likely to spread because in certain cases the tumor can be very aggressive. In these cases, the lymph nodes in the area will be carefully examined and additional diagnostic testing may be required to stage the squamous cell carcinoma.

Melanoma
When the pathology report confirms melanoma, additional diagnostic testing may be needed to stage the cancer because it is not always possible to determine from the tissue sample if:

  • The melanoma is confined to the local area where it was found.

  • Cancer cells have spread to lymph nodes or other areas, such as liver, intestines, brain, lungs, or bone.

When a melanoma tumor is thick enough to indicate that the cancer may have spread, a sentinel lymph node biopsy may be performed. This procedure is performed by a surgeon who begins by identifying the first lymph node, known as the "sentinel node," to receive lymph draining from the tumor. This is the node most likely to contain cancer cells. The sentinel node is found by injecting radioactive material into skin next to the tumor and tracing the flow of lymph from the site of the melanoma to the local and regional lymph nodes. Once the sentinel node is identified, it is surgically removed and sliced into sections for laboratory analysis to determine if melanoma cells are present. Sometimes, the surgeon will remove two or three nodes. The removed node(s) is sent to a pathologist who will examine the tissue to determine if cancer cells are present.

If a lymph node near the melanoma feels abnormally large or hard, a fine needle aspiration biopsy or open biopsy may be performed to determine if the cancer has spread to the lymph nodes. The fine needle aspiration biopsy is performed by inserting a thin needle into the lymph node in question and removing a small amount of tissue so that it can be examined under a microscope to find out if cancer cells are present. Occasionally, enough material cannot be withdrawn during a fine needle aspiration biopsy to make an accurate diagnosis, and another type of biopsy, such as an open biopsy may be necessary. An open biopsy is performed by surgically removing the lymph node in question. The removed node is sent to a pathologist for examination.

In some cases, diagnostic imaging techniques, such as the x-ray, computed tomography (CAT scan), magnetic resonance imaging (MRI), positron emission tomography (PET scan) and radio-isotopic bone or organ scan and/or blood studies may be used to determine if the cancer has spread to distant organs.

Results Determine the Stage. Once all procedures and tests have been completed and the results analyzed, the melanoma will be staged. The stage is determined by the:

  • Depth (how deeply the tumor has penetrated the skin)

  • Ulceration (a break, which can be microscopic, forms on the surface of the tumor and the cells on the surface die and are sloughed off)

  • Lymph node involvement, which indicates if the cancer has metastasized (spread) to the lymph nodes

  • Metastasis to distant organ(s)

While the staging system used for melanoma may vary slightly from hospital to hospital, melanoma staging is generally based on the 2002 American Joint Committee on Cancer (AJCC) melanoma staging system, which is shown in following table. This staging system was developed in 1983 and has been revised several times. The staging systems for cancer, including the one for melanoma, continue to evolve over time as researchers learn more.

When looking at the table, it is important to keep in mind that survival rates are statistical aggregates, and it is not possible to determine survival for an individual patient.

 
Stage
 

Medical Notation

Characteristics

5–year Survival Rate

Stage 0

Tis
NO
MO

What dermatologists call in situ melanoma. The cancer is limited to the outermost layers of the skin, the epidermis (Tis). No evidence that the cancer has spread to the lymph nodes or distant organs (NO, MO).

99.5% -100%
 

Stage IA

T1a
NO

MO

Thickness of lesion 1 mm or less (T1), the surface of the lesion is not broken (a) (without ulceration), and tumor extends beneath the epidermis to the dermis. No evidence that the cancer has spread to the lymph nodes or distant organs (NO, MO).

³ 95%

Stage lB

T1b

NO

MO

T2a

NO

MO

Melanoma 1 mm or less (T1) but has ulcerated (b), or melanoma is between 1.01 and 2 mm (T2) but has not ulcerated (a). No evidence that the cancer has spread to the lymph nodes or distant organs (NO, MO).

89 – 91%

Stage llA

T2b

NO

MO

T3a

NO

MO

Tumor between 1.01 and 2.0 mm (T2) and has ulcerated (b) or tumor between 2.01 and 4 mm (T3) and without ulceration (a). No evidence that the cancer has spread to the lymph nodes or distant organs (NO, MO).

77 – 79%

Stage llB

T3b

NO

MO

T4a

NO

MO

Tumor between 2.01 and 4 mm (T3) and has ulcerated (b) or tumor is 4mm or greater (T4) and has not ulcerated (a). No evidence that the cancer has spread to the lymph nodes or distant organs (NO, MO).

63 – 67%

Stage IIC

T4b

NO

MO

Tumor 4 mm (T4) or greater and has ulcerated (b). No evidence that the cancer has spread to the lymph nodes or distant organs (NO, MO).

45%

Stage lllA

T1-4a

N1a

MO

T1-4a

N2a

MO

Thickness of primary tumor ranges from 1 mm and 4 mm or greater (T1-4) and has not ulcerated (a). Evidence that cancer spread to a single regional (nearby) lymph node (N1) or 2–3 regional nodes (N2). N2a indicates cancer less severe than N2b or N2c. No evidence spread to distant organs (MO). At this stage, thickness of tumor no longer the most important prognostic indicator. 

63 – 69%

Stage IIIB

Any T
N1a – N2c
MO

Thickness of primary tumor may be any thickness (T) and may (b) or may not (a) have ulcerated. Evidence that cancer has spread to lymph nodes (N). No evidence spread to distant organs (MO).

30 – 53%

Stage IllC

Any T
Any N

MO

Primary tumor can be any thickness and has ulcerated. Evidence of lymph node involvement (N). No evidence spread to distant organs (MO).

24 – 29%

Stage IV

Any T

Any N

M1a, M1b, M1c

Primary tumor can be any thickness. Evidence of lymph node involvement (N), and melanoma has metastasized (M) to other organs (a = distant skin and subcutaneous tissue, b=lungs, c=all other distant organs, such as the liver or brain.) Prognosis is poor.

7 – 19%

Table shows the American Joint Committee on Cancer’s (AJCC) melanoma staging system that was revised in 2002, along with an explanation of the medical notation.

References:
Johnson, TM et al. “Staging Workup, Sentinel Node Biopsy, and Follow-up Tests for Melanoma.” Archives of Dermatology. 2004 Jan;140(1):107-13.

Kanzler, MH et al. “Malignant Melanoma.” Journal of the American Academy of Dermatology. 2003 May;48(5):780-3.

Swetter, SM. July 29, 2003. eMedicine: Malignant Melanoma. http://www.emedicine.com/derm/topic257.html


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