Answer:
Dear
Anthony,
Melanoma
is a cancer that begins in the melanocytes.
Melanoma
arises from melanocytes, which are cells located in the upper layer
of the skin that are responsible for producing pigment (skin color).
Most melanomas are dark in color (black/brown) because they contain
pigment; however, some melanomas do not contain pigment (amelanotic
malignant melanoma) and are difficult to diagnose.
Melanoma
can almost always be cured in its early stages. But it is likely to
spread to other parts of the body if it is not caught early. Melanoma
is much less common than basal cell and squamous cell skin cancers,
but it is far more serious.
The thicker
a melanoma is, the more likely it is to have spread to lymph nodes
at the time of diagnosis when melanoma spreads, it spreads to lymph
nodes in the region of the tumor first.
Lymph
nodes are small, bean-shaped structures that are part of the immune
system. They are found throughout the body and are interconnected
by lymph channels.
Melanoma
tends to spread through lymph channels that drain into lymph nodes
in the local area of the primary skin melanoma. Once a pathologist
has determined the thickness of the tumor, the next step in pathological
staging may involve surgical removal and examination of the local
lymph nodes to determine if apparently normal lymph nodes contain
melanoma cells.
There
is evidence that surgical removal of involved lymph nodes may improve
survival.
Melanoma
can spread by local extension (through the lymph system, as described
above) and/or by the blood to distant sites. Satellite lesions can
also occur in the skin adjacent but separate from the primary melanoma.
These
are sometimes called in-transit metastases, implying that secondary
melanomas have grown in the skin on their way to spreading to local
lymph nodes. Any organ can be involved by metastases from malignant
melanoma, but the lungs and liver are the most common sites
The majority
of patients with spread of melanoma to local lymph nodes cannot be
cured with current therapies.
The average
survival of patients with melanoma that has spread outside the local
area is only 7.5 months, with only 5-10% of patients surviving beyond
5 years.
Melanoma
is one of the few cancers that has shown regression without treatment.
Spontaneous partial regression can be common, but complete and permanent
regression is rare, with only 33 cases being documented in the world's
literature. It has been suggested that spontaneous regressions occur
because the patient's immune system rejects the cancer. This observation
has caused physicians to try treatments with interferons, interleukins,
vaccines and other treatments that stimulate the immune system to
react against the malignant melanoma.
Prognosis
of the disease: When the disease is confined to the site of origin,
the greater the thickness or depth of local invasion of the melanoma,
the higher the chance of lymph node metastases and the worse the prognosis.
Following
surgery, the highest risk of recurrence is within the first two years,
but late relapses are not uncommon.
Cure
rates are so high with melanoma in situ that there are essentially
no outstanding treatment issues.
The standard
treatment of stage I melanoma is surgical removal with pathologically
confirmed negative margins.
Stage
II melanoma has spread to the lower part of the inner layer of skin
(dermis), but not into the tissue below the dermis or into nearby
lymph nodes.
The surgical
treatment of stage II melanoma typically involves a single procedure
in which a local excision of the cancer is performed as well as a
SLN biopsy.
Stage
III melanoma includes cancers of any thickness with tumor spread to
regional lymph nodes. The extent or amount of tumor in the lymph nodes
is the most important prognostic factor for patients with stage III
melanoma.
Standard
surgical treatment for patients with stage III melanoma is removal
of the primary cancer with up to 2-centimeter (over an inch) margins
of the adjacent skin, depending on the thickness of the primary tumor,
and removal of all of the regional lymph nodes.
In the
stage IV, or metastatic, melanoma patients have cancer that has spread
from its site of origin to distant lymph nodes and/or distant sites.
Additional
prognostic factors for stage IV melanoma include site of distant metastases
and elevated blood enzyme LDH levels. Distant lymph node metastases
and lung metastases have a better prognosis than other distant metastases,
such as the brain or liver.
DTIC
(dacarbazine) is the standard chemotherapy agent for the treatment
of metastatic melanoma, with an overall response rate of approximately
15-20%.
