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Frequently asked questions & glossary

As you learn more about Merkel cell carcinoma (MCC), you may come across new questions or terms in your research. This list of frequently asked questions (FAQs) and definitions may help you understand this rare skin cancer. If you have any additional questions, your or your loved one's care team may be able to provide further information.

Frequently asked questions

What are risk factors for Merkel cell carcinoma?

Risk factors for MCC include sun exposure, a weakened immune system, being older than 50 years of age, being male, or being White.

What is the prognosis for Merkel cell carcinoma?

Disease prognosis depends on individual factors. Your healthcare team may be able to provide information more specific to you or your loved one’s condition.

Where does Merkel cell carcinoma spread to?

MCC typically spreads first to nearby lymph nodes, then may spread to lymph nodes or skin in distant parts of the body, lungs, brain, bones, or other organs.

How rare is Merkel cell carcinoma?

There are approximately 3,000 patients diagnosed with MCC in the U.S. each year.

What are Merkel cell carcinoma symptoms?

MCC typically appears as a single lump that:

  • Grows quickly
  • Is red or purple in color
  • Feels painless
  • Develops on sun-exposed skin (especially the head or neck)
  • Appears after 50 years of age

If you're concerned, talk to your doctor. Finding MCC early is very important, as it is a progressive skin cancer.

How is Merkel cell carcinoma treated?

Treatment depends on the stage of the disease and other factors, including the location of the tumor. Treatment options may include surgery to remove the lesion, radiation therapy, or immunotherapy if MCC has been diagnosed at a later stage and has spread or has returned after initial treatment.

ZYNYZ is an example of an immunotherapy for adults with MCC that has spread or returned.


CT scanStands for “computed tomography.” A procedure that uses a computer linked to an X-ray machine to make a series of detailed pictures inside of your body.
Duration of responseThe length of time your tumor responds to treatment.
ImmunosuppressantA type of treatment used to reduce immune system responses in conditions related to an overactive immune system or to prevent bone marrow or organ transplant rejection.
ImmunotherapyA type of treatment that helps the body’s own immune system fight cancer. Note: ZYNYZ is an example of an immunotherapy.
Lymph node biopsyA procedure where all or part of a lymph node is removed and examined under a microscope to look for signs of cancer.
Merkel cell carcinomaA rare, aggressive cancer where cancer cells grow in the skin.
Merkel cell carcinoma stagingThe process of seeing if and where cancer has spread. Early-stage Merkel cell carcinoma has not yet spread to other parts of the body, whereas later-stage MCC has spread. When cancer spreads, it is called “metastasis.”
PET scanStands for “positron emission tomography.” A procedure during which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner makes a picture of where the glucose is being used in the body. Since cancer cells take up more glucose than normal cells, the pictures are used to find cancer cells in the body.
Radiation therapyThe use of high-energy radiation to kill cancer cells or keep them from growing.
Tumor responseTumor response is measured via complete response (the disappearance of all signs of cancer) and partial response (a decrease in the size of the tumor or in the extent of cancer in the body).
Skin biopsyA procedure where a small piece of your skin is removed and examined under a microscope to look for signs of cancer.
Skin lesionAn area of abnormal tissue on your skin.


What is the most important information I should know about ZYNYZ?

ZYNYZ is a medicine that may treat a certain type of skin cancer by working with your immune system. ZYNYZ can cause your immune system to attack normal organs and tissues in any area of your body and can affect the way they work. These problems can sometimes become severe or life-threatening and can lead to death. You can have more than one of these problems at the same time. These problems may happen anytime during treatment or even after your treatment has ended.

Call or see your doctor right away if you develop any new or worsening signs or symptoms, including:

Lung problems: cough, shortness of breath, chest pain

Intestinal problems: diarrhea (loose stools) or more frequent bowel movements than usual; stools that are black, tarry, sticky, or have blood or mucus; severe stomach-area (abdomen) pain or tenderness

Liver problems: yellowing of your skin or the whites of your eyes; severe nausea or vomiting; pain on the right side of your stomach area (abdomen); dark urine (tea colored); bleeding or bruising more easily than normal

Hormone gland problems: headaches that will not go away or unusual headaches; eye sensitivity to light; eye problems; rapid heartbeat; increased sweating; extreme tiredness; weight gain or weight loss; feeling more hungry or thirsty than usual; urinating more often than usual; hair loss; feeling cold; constipation; your voice gets deeper; dizziness or fainting; changes in mood or behavior, such as decreased sex drive, irritability, or forgetfulness

Kidney problems: decrease in your amount of urine, blood in your urine, swelling of your ankles, loss of appetite

Skin problems: rash; itching; skin blistering or peeling; painful sores or ulcers in your mouth or nose, throat, or genital area; fever or flu-like symptoms; swollen lymph nodes

Problems can also happen in other organs and tissues. These are not all of the signs and symptoms of immune system problems that can happen with ZYNYZ. Call or see your doctor right away for any new or worsening signs or symptoms, which may include:

  • chest pain, irregular heartbeat, shortness of breath, or swelling of ankles
  • confusion, sleepiness, memory problems, changes in mood or behavior, stiff neck, balance problems, tingling or numbness of the arms or legs
  • double vision, blurry vision, sensitivity to light, eye pain, changes in eyesight
  • persistent or severe muscle pain or weakness, muscle cramps
  • low red blood cells, bruising

Infusion reactions that can sometimes be severe. Signs and symptoms of infusion reactions may include: chills or shaking, itching or rash, flushing, shortness of breath or wheezing, dizziness, feel like passing out, fever, back or neck pain

Rejection of a transplanted organ. Your doctor should tell you what signs and symptoms you should report and monitor you, depending on the type of organ transplant that you have had.

Complications, including graft-versus-host disease, in people who have received a bone marrow (stem cell) transplant that uses donor stem cells (allogeneic). These complications can be serious and can lead to death. These complications may happen if you underwent transplantation either before or after being treated with ZYNYZ. Your doctor will monitor you for these complications.

Getting medical treatment right away may help keep these problems from becoming more serious. Your doctor will check you for these problems during your treatment. Your doctor may treat you with corticosteroid or hormone replacement medicines and may also need to delay or completely stop treatment if you have severe side effects.

Before you receive ZYNYZ, tell your doctor about all of your medical conditions, including if you:

  • have immune system problems such as Crohn’s disease, ulcerative colitis, or lupus
  • have received an organ transplant
  • have received or plan to receive a stem cell transplant that uses donor stem cells (allogeneic)
  • have received radiation treatment to your chest area
  • have a condition that affects your nervous system, such as myasthenia gravis or Guillain-Barré syndrome
  • are pregnant or plan to become pregnant. ZYNYZ can harm your unborn baby

Females who are able to become pregnant:

  • Your doctor should do a pregnancy test before you start treatment.
  • You should use an effective method of birth control during your treatment and for 4 months after your last dose. Talk to your doctor about birth control methods that you can use during this time.
  • Tell your doctor right away if you become pregnant or think you may be pregnant during treatment.
  • are breastfeeding or plan to breastfeed. It is not known if ZYNYZ passes into your breast milk. Do not breastfeed during treatment and for 4 months after your last dose.

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

The most common side effects of ZYNYZ include tiredness, muscle and bone pain, itching, diarrhea, rash, fever, nausea

These are not all the possible side effects of ZYNYZ. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

General information about the safe and effective use of ZYNYZ

Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. If you would like more information about ZYNYZ, talk with your doctor. You can ask your doctor for information about ZYNYZ that is written for health professionals.

Please see the accompanying full Prescribing Information, including Medication Guide, for ZYNYZ.