Cancer types

Merkel cell carcinoma

Melanoma, basal and squamous cell skin cancers, and Merkel cell carcinoma.

- A rare, fast-growing skin cancer of the nerve-like (neuroendocrine) cells of the skin.
- Usually a painless, firm, shiny red or purple lump that grows quickly over weeks, often on the head, neck or arms of older adults.
- Linked to sun damage, a weak immune system, and a common virus (Merkel cell polyomavirus).
- It often spreads to lymph nodes, but responds very well to radiotherapy and immunotherapy.

Before starting chemotherapy, immunotherapy or targeted therapy, these tests check that you are fit for treatment, and give a starting point to compare with later.

Test	Why it is done
CBC (complete blood count)	Haemoglobin, white cells and platelets. Treatment can lower them.
RFT (kidney function)	Many medicines are cleared by the kidneys; the dose may need to change.
LFT (liver function)	Many medicines are processed by the liver.
Viral markers: HBsAg, anti-HCV, HIV	Hepatitis B can flare up during treatment. If positive, a tablet is given to prevent this.
Blood sugar (and HbA1c if diabetic)	Steroids given with chemotherapy can raise blood sugar.
ECG and 2D Echo	Check the heart rhythm and pumping before treatment, as some medicines affect the heart.

Before immunotherapy, also:

Test	Why it is done
Serum TSH (thyroid)	Immunotherapy can affect the thyroid gland.
Serum cortisol (morning sample)	Immunotherapy can affect the adrenal and pituitary glands.

Sometimes needed, depending on your treatment:

Pregnancy test for women who could be pregnant.
Calcium and magnesium: for example before cisplatin or bone-strengthening injections.
Dental check-up before bone-strengthening injections (zoledronic acid or denosumab), as they can rarely affect the jaw bone.
Hearing test before cisplatin, in some patients.
Clotting tests (PT/INR) before a biopsy or chemoport.

Your doctor will choose the tests that apply to you. Some of them are repeated during treatment.

- The sentinel node and PET-CT decide the stage and the extent of radiotherapy.
- Surgery and radiotherapy are planned together so that treatment is not delayed.

Tap your stage on the map.
Tap your stage on the map.
- 1. Wide excision with sentinel node biopsy.
  2. Radiotherapy to the area, and to the lymph nodes if involved or not tested.
  3. Radiotherapy alone if surgery is not possible.
  4. Immunotherapy after surgery is being tested and may be offered for high-risk disease.
  What the research shows
  - ADMEC-O: nivolumab after surgery lowered the chance of return in a small trial; larger trials are ongoing.
  Side effects: surgery · radiotherapy
- 1. Immunotherapy: avelumab, pembrolizumab or retifanlimab.
  2. Chemotherapy (carboplatin or cisplatin with etoposide) if immunotherapy is not possible; responses are usually short.
  3. Radiotherapy to relieve symptoms.
  What the research shows
  - JAVELIN Merkel 200 and KEYNOTE-017: immunotherapy shrank the cancer in about half of patients when used first, and many responses lasted for years.
  Side effects: immunotherapy · chemotherapy
Tap a treatment on the map.
- - A scar; sometimes a skin graft.
  - After lymph node surgery: fluid collection and swelling of the limb.
- - Skin redness and soreness, tiredness.
  - Swelling of the arm or leg if the lymph nodes were treated.
- - The immune system can affect normal organs: thyroid, skin (rash, itching), bowel (loose stools), lungs (cough, breathlessness) and liver.
  - These can happen months after starting, or even after stopping. Report any new symptom, even if it seems small.
  - Thyroid, cortisol and liver blood tests are checked regularly.
  More about immunotherapy · Side effects of your regimen
- - Nausea and vomiting: well controlled with medicines given before and after chemotherapy.
  - Low blood counts and infection risk: fever of 38°C or more needs urgent care.
  - Tiredness, mouth sores, loose stools or constipation.
  More about chemotherapy · Side effects of your regimen
- Protect your skin from strong sun (shade, clothing, a hat, sunscreen SPF 30 or more), and check your whole skin every month.
- Skin and lymph node check every 3 to 6 months for 3 years, with scans and the virus antibody test, as most recurrences happen early.
- Mind and emotions

This information is general. Your own treatment plan may be different. Please discuss it with your doctor.

Written and medically reviewed by Dr Prathyusha Eaga, MD, DM (Medical Oncology). Last reviewed: 12 October 2026. Based on NCCN and ESMO guidelines.

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