Once melanoma has been diagnosed, imaging and other tests may be
done to see if the cancer has spread to other organs. Typically, these tests
are not required for cases of early melanoma, since it is unlikely that the
disease has spread.
What It Means: In Situ vs. Invasive
If your doctor describes the melanoma as in situ this indicates melanoma that remains on the outermost layer
of your skin (epidermis) and is in one area. A diagnosis of invasive melanoma describes a more
serious condition, in which the tumor has spread more deeply into the skin or
to other organs.
To date, a biopsy is
considered the most accurate method for testing melanoma. A sentinel lymph node biopsy (SLNB) may be used in some cases
to see if the cancer has spread to nearby lymph nodes. During this procedure, a
dye is injected into the area from which melanoma was removed. The first of the
lymph nodes to absorb the dye are then removed and tested for cancer.
Additional imaging tests for advanced cases of melanoma may
- CT Scan
- bone scan
Based on the
test results, doctors then establish the stage of the melanoma. Staging helps
determine the outlook and course of treatment for patients. It follows a scale
ranging from zero continuing through the Roman numerals I – IV (one to four),
with stage IV being the most advanced and serious stage in which the cancer has
spread (metastasized) to other organs.
Joint Committee on Cancer (AJCC) recently updated its publication, Cancer Staging Manual, 7th
edition, to provide the most comprehensive reference for cancer staging and
classification, including new discoveries about melanoma. A brief overview of
the five stages includes:
In this stage, the melanoma is non-invasive,
meaning it has not spread beyond the epidermis.
In this stage, the melanoma is invasive, but considered
to hold a small risk of having spread to the lymph nodes.
At this point, the melanoma has become
thicker. This stage is divided into several categories which are based on the
thickness of the melanoma.
In this stage, the melanoma may be of any
thickness and has spread to the lymph nodes or to the next, deeper layer of
skin. A biopsy can help determine if a tumor has spread beyond the original
The final and most advanced
stage, at this point, the melanoma has spread to lymph nodes or internal
organs, such as the lungs, liver, brain, and bone.
in determining a treatment plan involves the thickness of the melanoma, as
viewed beneath a microscope. Generally, thinner melanomas are less likely to
spread while a thicker melanoma is more serious.
Advances in Testing
biopsy provides an accurate testing method for diagnosing melanoma, it does
have its drawbacks, such as inaccuracy in determining the extent of the
melanoma, and lacking the full capability to help professionals find the right
course of treatment. The medical community continues to seek more effective
alternatives, and has discovered some promising findings.
In a recent
publication of The Journal of the
Federation of American Societies for Experimental Biology (FASEB Journal),
researchers revealed an encouraging advance in melanoma testing. It involves GPNMB, a protein found in melanoma
cells. Led by Dr. Toshihiko Hoashi, researchers discovered that the protein
shows up in melanocytes (the cells
that make melanin) but not in other skin cells, suggesting that GPNMB plays a
pivotal part in melanoma development. More research is needed to understand the
role of GPNMB and how, exactly, it is involved in the melanin-production process,
but the discovery does provide yet another step toward early detection of