Factors for Staging Melanoma
When a biopsy shows that melanoma is present, the first thing doctors will need to determine is the “stage” of the cancer. There are five stages, Stage 0 and Stages I through IV (one through four). Determining your stage is very important because your stage will help determine your treatment options and prognosis.
How Stage Is Determined
- Clinical information: Describes the overview of all the information gathered through testing and exams (physical exam, x-rays, CT scan, etc).
- Pathological information: This combines information from the original biopsy (Breslow depth, ulceration, mitotic rate, Clark level, etc) and biopsies of the lymph nodes and other organs.
Factors in Staging
The following factors are gathered from the clinical and pathological information to determine the stage of melanoma:
- Tumor Thickness: Indicates how deeply the tumor has penetrated the skin. It is measured by Breslow Depth.
- Breslow Depth: It measures in millimeters how thick the actual primary tumor is. It is measured in millimeters (1mm= less than 1/16 inch). Breslow depth is measured starting at the outer layer of the epidermis downward to the deepest extension of the melanoma. The thicker the tumor is, the greater the chance it has metastasized or spread to regional lymph nodes or distant sites.
- Clark Level: It describes how deeply the primary tumor has penetrated the different levels of the skin. It is now only used to stage thin melanomas (< 1mm).
- Tumor Ulceration: Ulceration is not the same as skin ulcers, which are open wounds. Ulceration means that, when seen under a microscope, the epidermis (top layer of the skin) that covers the primary melanoma is not intact. Ulceration cannot be seen with the naked eye. Ulcerated tumors pose a greater risk for metastatic disease than tumors that are not ulcerated.
- Mitotic Count (Rate): The number of cancer cells that are in the process of dividing when a pathologist looks at a tissue specimen microscopically. Higher mitotic rates (having more cells that are rapidly dividing) means that the cancer is more likely to grow and spread.
- Number of Metastatic Lymph Nodes: The greater the number of lymph nodes containing melanoma the poorer the prognosis.
- Microscopic or Macroscopic Metastasis to the Lymph Nodes:
- Micrometastases are tiny tumors not visible to the naked eye. They are commonly detected through a microscope after a biopsy of the sentinel lymph node.
- Macrometastases are felt during a physical examination or can be seen by the naked eye when inspected by a surgeon or pathologist. Their presence is usually confirmed by a biopsy or dissection of the lymph node or by being able to see that the tumor extends beyond the lymph node capsule.
- Although progression and risks are different for every patient, in general, macrometastases have a poorer prognosis than micrometastases.
- Site of Distant Metastasis: Melanoma that has spread to other areas (distant metastases) of the skin, like the underlying subcutaneous tissue, or distant lymph nodes, have a relatively better prognosis than melanoma that has spread to any other site in the body.
- LDH Level (lactate dehydrogenase): LDH is found in the blood and many body tissues. Higher LDH levels correspond with a greater likelihood that melanoma has spread (metastatic disease) and a poorer prognosis than normal LDH levels.