What do the staging categories in melanoma mean?

Stage 0 or Tis (in situ)

Melanoma in situ (at site only).  Melanoma cells are confined to the epidermis (top layer of skin). No local spread, no lymph node involvement, no systemic spread. Treatment is surgical excision of lesion. Over 95% of patients with this stage whose melanoma has been surgically removed are considered cured (Weaver, 2002).

Stage I

Primary melanoma is less than 2.0 mm, is found in the skin but has not spread to the lymph nodes or other body parts.  Presence of ulceration increases staging.

Stage II

Primary melanoma is between 1.01 – 4 mm, has spread to the lower level of the skin (dermis) but not the lymph nodes or other body parts.  Presence of ulceration increases staging.

Stage III

Primary melanoma is between 1.01 – 4 mm and has spread to the regional lymph nodes but not distant body parts.  Amount of lymph node involvement is the critical element in differentiating between Stages IIIA, IIIB, and IIIC.

Stage IV

Primary melanoma is between 1.01 – 4 mm and has spread to regional lymph nodes, distant lymph nodes and/or distant body parts.  Elevated LDH levels increase staging.  Site of distant metastasis is important.

What is the difference between clinical and pathological staging?

Staging is further predicated on both the clinical picture and the pathological results.  Clinical staging involves what is found during the physical exam, in radiology (x-rays, CT, MRI, PET scans), and the results of the laboratory reports on the excised tumor.  Pathological staging uses all the clinical staging results plus the reports from the path lab derived from partial (sentinel) or complete lymph node removal.  More in depth pathologic staging includes looking at micrometastasis (lymph nodes that are found to have melanoma only after being surgically excised and examined under the microscope in the pathology lab; these nodes were not found during the clinical exam or by radiology reports), macrometastasis (lymph nodes that are enlarged and are palpable during the physical exam or on radiology reports before they have been surgically removed), and in-transit satellites (lesions that are found more than 2 cm from the primary tumor but still within the skin tissues).  It was once thought that melanoma spread only macroscopically via the blood and lymphatic systems. Now, with the advent of sentinel lymph node biopsy, small microscopic tumors previously undetectable by clinical exam or radiologic testing have been found in the adjacent tissues not far from the original tumor.  These are called satellite (found within 2 cm of primary tumor) or in-transit metastases (found more than 2 cm from primary tumor). 

Now that I know the TNM classification, how can I determine my stage?

Once you have the TNM classification, there are two stage groupings based on the clinical and pathological stage as explained previously.  These will be more important to your medical team as they will help delineate the type of treatment.  As a patient, you will want to know if you are Stage 1, Stage 2, etc.

Take our previous example of a T2bN0M0.  Look at the tables for this numeration.  It is both a clinical and pathological Stage IIA.  So, you would look under Stage IIA melanoma treatment and prognosis for further information.  The clinical and pathological stages are the same for Stages 0-IIC.  Since clinical staging relies on external “looks” at the lymph nodes, it is cannot be differentiated as well pathological staging for Stages III-IV.  This is because the pathological staging includes the surgical excision of lymph nodes and their microscopic examination, an “internal” look at the nodes. 

Clinical Stage Grouping

Pathologic Stage Grouping

Tables adapted from American Joint Committee on Cancer, 2002.  www.cancerstaging.net/chapter.pdf

What are the new changes for staging melanoma?

In June 2002, the staging for melanoma was rewritten and included new changes based on numerous studies.  The actual thickness of the tumor (Breslow’s Thickness) is more important than the depth (Clark’s Level) of skin invasion with the exception of melanomas < 1mm.  The presence of ulceration upgrades the severity of the melanoma. The amount of lymph nodes involved is more critical than the size of the nodes affected. The presence of satellite or in-transit metastases and the incorporation of clinical and pathologic staging have been included due to research from sentinel lymph node studies.  In advanced melanomas, it is critical to know where it has spread, how many sites, and the LDH blood reading.  Melanomas that spread to the extremities carry a better prognosis than those that spread to the internal organs. A lower number of spread sites favors a better prognosis.  Elevated levels of LDH indicate a more aggressive tumor.