Melanoma: How It Returns, Where It Spreads
Melanoma is known as "the
most lethal form of skin cancer" because it accounts for 77% of all
deaths from skin cancer. Melanoma can spread rapidly - and with the
exception of some rare forms of skin cancer — it is the skin cancer
most likely to spread to lymph nodes and internal organs. Melanoma
also may recur (return after treatment).
For these reasons, everyone treated for melanoma should continue a
lifetime of regular:
Should melanoma return, it will recur in one of these ways:
Melanoma that develops in or near the
site where the primary melanoma was completely removed is called
"local recurrence." Recurrence is often an indication that the tumor
has metastasized. Patients who have locally recurrent melanoma after
the primary tumor has been removed have a low rate of survival.
Local recurrence can occur months to years after surgical removal of
the primary tumor.
A "second primary" is defined as a
new melanoma that develops at another site on the patient’s body
either simultaneously or after complete removal of the primary
tumor. All patients who have had melanoma are at risk of developing
a second primary. This risk increases if you have atypical moles (dysplastic
nevi) or a family history of melanoma.
It is vital that anyone who has had melanoma continue
self-examinations and see a dermatologist for regular full-body skin
examinations as often as prescribed. Early detection increases the
likelihood that the second primary will be detected when it is in an
early and curable stage.
Recurrence at a distant site.
Recurrence at a distant site is known
as "metastatic melanoma," which means the cancer has spread.
Metastasis is a risk for anyone who has been treated for melanoma.
However, when the primary melanoma (original tumor) is thin (less
than 1 millimeter in thickness), surgical removal offers a complete
cure in 95% of patients because the melanoma tends to be confined to
the top layers of skin and is not likely to spread. This does not
mean that you can be lax about self-examinations and checkups. Since
5% of thin melanomas are not completely cured, it is extremely
important to perform regular self-examinations of your skin and
lymph nodes and keep all appointments for checkups.
When your physician suspects that the melanoma may have spread,
diagnostic testing will be conducted to determine if the cancer has
spread and to where. Tests used to determine if melanoma has spread
include blood tests, x-rays, and other imaging studies. Your
dermatologist or oncologist will determine which diagnostic tests
When melanoma cells spread from the primary tumor, they first pass
through the lymph channel nearest the melanoma. Once melanoma has
spread to the regional lymph nodes (nodes nearest the tumor), there
is a risk that the melanoma will spread to distant sites (other
lymph nodes and organs). Once melanoma has spread to distant sites,
it is in stage IV. Treatment in stage IV may include selective
surgical excision, chemotherapy, immunotherapy, and radiation
therapy. However, the prognosis is poor, and organ failure often
causes death. It is important to know that some people do survive
stage IV melanoma.
In stage IV, melanoma can metastasize to organs in nearly every part
of the body. However, cancer cells do not randomly shoot off in all
directions. Each type of cancer (breast, pancreatic, etc.) has a
strong likelihood of spreading to certain sites more often than
others. The following table shows what organs melanoma is most
likely to travel to once it spreads.
Spreading to Organ
(other areas of the skin), subcutaneous tissue and lymph nodes
and area between the lungs
Table 1: Where Melanoma Most Likely
Source: Meyers ML, Balch CM.
“Diagnosis and Treatment of Metastatic Melanoma.” Cutaneous
Melanoma. Balch CM, Houghton AN, Sober AJ, Soong S-J (Eds): St.
Louis: Quality Medical Publishing, Inc. 1998:329.
Why Melanoma Spreads to Specific Organs
While scientists know where melanoma is most likely to spread, it is
not clear why different cancers are more likely to metastasize to
specific sites. Scientists have three hypotheses:
Cancerous cells indiscriminately
colonize at any distant site, but multiply only in those sites that
have appropriate cellular growth factors
Cancerous cells become "glued" to
Cancerous cells are selectively
attracted to specific sites by organ-specific molecules — a process
A study published in March 2001
analyzed breast cancer and melanoma because both cancers tend to
spread to the lymph nodes, lungs, liver, and bone. Researchers found
that organ-specific chemoattractive molecules called "chemokines"
are released from various organs and tend to attract circulating
cancer cells to metastasize to a specific site. Melanoma’s tendency
of spreading to the skin correlated with the presence of a
skin-specific chemokine and a high level of corresponding chemokine
receptors in melanoma cells. The researchers found that the melanoma
cells had many more chemokine receptors than the cells not affected
Why Follow-up Examinations So Important
It is important for patients to know that melanoma can spread
"silently," meaning that the patient does not experience symptoms.
This makes follow-up examinations vital. Be sure to perform regular
self-examinations of your skin and lymph nodes as instructed and
keep all dermatologic appointments for follow-up examinations.
Muller A, Homey B, Soto H et al. “Involvement of chemokine receptors
in breast cancer metastasis.” Nature 2001; 410:50-56.
content solely developed by the American Academy of Dermatology