What Is Metastatic Melanoma?
Metastatic melanoma is a
starts in the cells capable of producing a colored pigment called melanin and
then has spread beyond its original skin location. It may already be
present at the time of the primary or initial diagnosis of the melanoma, or may show up later after surgery has been
performed. Metastatic melanoma may spread through the bloodstream or the lymph
What Are Metastatic Melanoma Symptoms and Signs?
When melanoma spreads through the bloodstream, the signs and symptoms
will depend upon which organ system is involved and how much the tumor has grown
there. Metastatic melanoma may be initially painless and symptom-free or may
demonstrate ongoing problems according to the site. With lymphatic spread,
swollen lymph glands or a string of nodules in the skin may be the presentation.
These also are usually painless.
Tumor metastasis into the liver may cause
weight loss, nausea, a swollen liver, and abnormal blood tests. Tumor in lymph
nodes may cause swelling of the extremities and enlarged glands. Tumor in the
lungs may cause shortness of breath, cough, and bloody sputum. Tumor in the
brain may cause headaches, dizziness, and seizures. Tumor in bone may cause bone
pain or unusual fractures.
Melanoma may spread to other areas of the skin and may be bluish-gray or
flesh-colored nodules depending upon the amount of melanin in the tumor and
depth in the skin. In staging melanoma, stage 3 is defined as local spread
through lymphatic drainage (sentinel node biopsy helps with staging here), and
stage 4 is defined as distant spread (metastasis) to other organs, presumably by
spread through the bloodstream.
What Are the Treatments for Metastatic Melanoma?
Ideally, melanoma is diagnosed and treated surgically while it is still
small and thin and before it has had the chance to metastasize. The prognosis
and survivability of metastatic melanoma remain poor compared to other types of
cancer. Metastatic melanoma is less responsive to radiation therapy and
traditional forms of chemotherapy than other forms of cancer.
which the body's own immune system is used to fight the tumor has been a focus
of research for decades and immune system "stimulants" such as interferon-alpha
and interleukin-2 have also been tried for many years.
A variety of newer
medications target different points in the biologic pathways of melanoma growth
and spread. The following are drugs currently in use, or being actively
investigated. More should be available shortly.
- Inhibition of kinase enzymes
needed in cell reproduction like MEK: cobimetinib (Cotellic), trametinib (Mekinist)
- Target cell growth signals from abnormal BRAF genes: dabrafenib (Tafinlar),
vemurafenib (Zelboraf), nivolumab (Opdivo)
- Improve immune response to the
tumor: pembrolizumab (Keytruda), ipilimumab (Yervoy)
As monotherapy (used by
themselves), these drugs have not been shown to dramatically improve survival
even if they did improve disease-free time. The hope is that combinations of
medications targeting more than one part of the melanoma growth and metastasis
pathway will provide more encouraging results.
All these medications have
significant side effects, including life-threatening ones, and are indicated only
for stage 3 tumors to try to prevent recurrence and spread, and stage 4
metastatic tumors which are no longer amenable to surgery.
What Are the Prognosis and Survival Rates for Metastatic Melanoma?
The prognosis for thin melanomas completely removed by surgery remains quite good although patients require long-term monitoring to watch for both new melanomas as well as evidence of late recurrence and previously undiagnosed metastasis of the original one. Survival rates for melanoma, especially for metastatic melanoma, vary widely according to many factors, including the patient's age, overall health, location of the tumor, particular findings on the examination of the biopsy, and the depth and stage. Survival statistics are generally based on five-year survival. Much of the success reported for the targeted therapies focus on "disease free" time because, in many cases, the actual five-year survival is not affected. It is hoped that combination therapy with two or more agents targeting different stages of the melanoma cell cycle will change that.
- For stage 1 (thin melanoma, local only), five-year survival is near 100%.
- For stage 2 (thicker melanoma, local only), five-year survival is 80%-90%. (The reason for reduced survival rate is that even if the primary skin tumor has been completely removed, it had already metastasized by the time surgery was performed.)
- For stage 3 (local and nodal metastasis), five-year survival is around 50%.
- For stage 4 (distant metastasis), five-year survival is 10%-25% depending upon sex and other demographic factors.