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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:
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Plan appropriate treatment
-
Provide a prognosis (survival rate and
risk of recurrence)
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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:
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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)
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Lymph node involvement, which indicates
if the cancer has metastasized (spread) to the lymph nodes
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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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