ALL ABOUT MERKEL CELL CARCINOMA
WHAT IS A MERKEL CELL
Merkel cells were first described in the late 1800s by a German doctor named Friedrich Merkel.
Merkel cells are found in the top layer of the skin (epidermis) in the layer of basal cells at the deepest part of the epidermis. Merkel Cells are very close to the nerve endings that receive the sensation of touch.
Merkel cells are a type of neuroendocrine cell that share features of both nerve cells and hormone-making cells.
MERKEL CELL CARCINOMA (MCC)
MCC is a neuroendocrine carcinoma of the skin that forms when Merkel cells grow out of control. However, recent research suggests that MCC is unlikely to originate from normal Merkel cells.
Merkel Cell carcinoma is an aggressive skin cancer with a poor prognostic outcome.
80% of MCC are linked to the Merkel cell polyomavirus (MCPyV) while 20% of MCC cases are linked to ultraviolet light exposure
MCPyV is not infectious and cannot be passed on to other people.
Researchers don’t yet know all of the DNA changes that can result in MCC, but they have found that many MCC cases have changes in tumor suppressor genes, leading to uncontrolled cell growth.
MCC is a somatic mutation that occurs during a person's lifetime and does not appear to be inherited from parents or to run in families.
Even with treatment, MCC commonly spreads (metastasizes) beyond the skin to nearby lymph nodes
STATISTICS
MCC is a rare type of skin cancer.
1 in 130,000 people will be diagnosed with MCC.
MCC is 40 times rarer than Melanoma
MCC is approximately 3-5x deadlier than Melanoma, but with early detection, MCC can be treated successfully.
Studies show that the risk of recurrence was higher among patients whose tumors did not contain the MCPyV virus (virus-negative MCC tumors).
Thanks to advances in the field of immunotherapy, MCC survival rates are improving.
INCREASED INCIDENCE
Between 2000–2013, there was a 95% increase in the number of reported MCC cases, compared to 57% for melanoma and 15% for all ‘solid’ cancers.
An aging population is driving brisk increases in the number of new MCC cases in the US.
Due to the aging of the Baby Boomer generation, US MCC incident cases are predicted to climb to 2835 cases/year in 2020 and 3284 cases/year in 2025.
This growing impact combined with a rapidly evolving therapeutic landscape warrants expanded awareness of MCC diagnosis and management.
Read more about increased incidences of MCC here: https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=29102486
RISK FACTORS*
- Older age- 50 years and above but may occur at any age.
- Slightly more common in men.
- Fair skin
- A weakened immune system however over 90% of people who get MCC have no known immune suppression.
- Exposure to a lot of natural sunlight
- Exposure to artificial sunlight, such as from tanning beds or psoralen and ultraviolet A (PUVA) therapy for psoriasis.
- Taking drugs that make the immune system less active, such as after an organ transplant or HIV.
- Having a history of skin cancer & other types of cancer.
While most people have been exposed to MCPyV by adulthood it appears that the virus does not cause any symptoms except in the very rare situations in which it leads to MCC.
*Note: This list is not inclusive. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Ask your doctor if you think you may be at risk.
SIGNS AND SYMPTOMS
Merkel cell cancers usually start on the skin exposed to sunlight, but some appear in non-sun exposed areas of the body.
They usually start as a painless firm bump. This may be red, blue, violet, or just skin-colored. This is called the primary site.
The most commonplace for MCC is the head or neck, followed by the shoulder, arm, or hand. A smaller number may appear in the leg or hip. The least common spot is on the trunk
A small number of Merkel Cell cancers have no primary site.
DIAGNOSIS AND TESTING
Skin biopsy:
- The diagnosis of MCC is made with a skin biopsy which is then examined under the microscope by a pathologist.
Sentinel lymph node biopsy:
- The sentinel lymph node is the first lymph node that connects to the part of the body where the cancer arose.
- Merkel cell carcinoma can travel from the skin, through the lymphatic vessels, to the sentinel lymph node.
- If a lymph node feels enlarged, it may contain MCC (macrometastases). Sometimes, lymph nodes may contain MCC, but not feel enlarged (micrometastases).
- Lymph nodes should be removed (biopsied) to determine if MCC is present.
CT scan or PET-CT :
- If a biopsy reveals MCC, scans are often obtained to determine if there is evidence that the cancer has already spread.
TREATMENT & PROGNOSIS
Factors that determine your treatment plan depend upon:
- How early your doctor diagnosed your cancer
- Overall health
- Whether cancer cells have spread to other tissues in your body (metastasis)
The stage at diagnosis is the major determinant of the chance for later spread (metastasis) and treatment options.
See more info regarding staging at https://merkelcell.org/testing-and-diagnosis/staging/
Treatment for MCC usually involves one or a combination of therapies, including:
- Surgery, to remove the cancerous tissues.
- Immunotherapy, which uses specific medications to help your immune system fight cancer. Thanks to advances in the field of immunotherapy, MCC survival rates are improving
- Radiation therapy, which uses highly charged particles to kill cancer cells. This method is often combined with surgery and/or immunotherapy to improve results.
- Chemotherapy, which uses drugs to kill cancer. This method of treatment was previously used more often but was not found to give lasting results.