• Merkel cell polyomavirus (MCPyV) status: About eight in ten Merkel cell carcinomas are driven by a common skin virus that has stitched itself into the tumour's DNA; the virus-negative rest are driven by sunlight and carry a huge mutation load.
• The margin in skin cancer surgery: When a skin cancer is cut out, the surgeon takes a rim of normal-looking skin around it, because the cancer reaches further than the eye can see.
• Skin cancer after an organ transplant: The drugs that keep a transplanted organ alive let skin cancers grow, and they grow differently: faster, in numbers, and far more likely to spread.
• Keratinocyte cancer (and why 'non-melanoma skin cancer' is being retired): The two commonest cancers in the world, basal cell carcinoma and cutaneous squamous cell carcinoma, both arise from keratinocytes, the cells that make up most of the outer layer of skin.
• Radiotherapy for skin cancer: Radiotherapy cures most skin cancers without an operation, and is chosen when surgery would take too much, when someone is too frail for it, or when they refuse it.
• Why nobody knows how many skin cancers there are: the counting rule behind every figure: Cancer registries were never built to count a cancer that people get several of.
• How skin carcinoma is staged in Britain: UICC TNM, and why it is not the American system: UK skin carcinoma reports are staged against the UICC's system, not the American AJCC's, and the two are not the same: the American manual covers only the head and neck, while the UICC covers the whole body and includes basal cell carcinoma.
• What makes a skin cancer high risk: the UK feature lists: Low risk and high risk are the words that actually decide what happens to a keratinocyte cancer in Britain, more than any stage.
• Immune-related adverse events (irAEs): Immune-related adverse events (irAEs) are the autoimmune side effects of checkpoint inhibitors: colitis, thyroid problems, rash, hepatitis, pneumonitis.
• Tumour mutational burden (TMB): How many mutations a tumour has.

Biomarker results to ask for: CK20 perinuclear dot staining; TTF-1 negative, MCPyV large T antigen (IHC/PCR), MCPyV oncoprotein antibody titre (surveillance), Sentinel lymph node status, PD-L1 (not required for treatment), Tumour mutational burden (virus-negative).

Bring copies of scan reports, pathology and blood results, and a list of every medicine and supplement.

• Localised (stage I-II): Wide local excision with sentinel node biopsy; adjuvant radiotherapy to the primary site (and nodal basin if node-positive); adjuvant nivolumab supported by ADMEC-O in selected patients. (Sentinel lymph node biopsy, IMRT / IGRT (modern external beam), Nivolumab)
• After complete resection: what the adjuvant evidence does and does not show: ADMEC-O randomised 179 patients with completely resected Merkel cell carcinoma 2 to 1 to a year of nivolumab or to observation. Disease-free survival was 85 per cent at 12 months and 84 per cent at 24 with nivolumab against 77 and 73 per cent with observation, a hazard ratio of 0.58 whose 95 per cent confidence interval, 0.30 to 1.12, crosses one; the authors state it as an absolute risk reduction of 9 and 10 percentage points. Grade 3 or 4 adverse events occurred in 42 per cent against 11 per cent. Overall survival had ten events against six in a group half the size and is not mature. This is a phase 2 signal in a rare disease, not a proven standard, and the randomised phase 3 that would settle it, STAMP, has not reported. (ADMEC-O (adjuvant nivolumab in completely resected Merkel cell carcinoma), STAMP (EA6174), Nivolumab, Immune-related adverse events (irAEs))
• Regional nodal disease (stage III): Lymphadenectomy and/or nodal radiotherapy; neoadjuvant nivolumab (CheckMate 358) produced pathological complete responses in about half. (Nivolumab, IMRT / IGRT (modern external beam))
• Metastatic, first line: Avelumab, pembrolizumab or retifanlimab; ~50% response with most responses durable. (Avelumab, Pembrolizumab, Retifanlimab)
• Choosing among the three PD-1 pathway antibodies: Avelumab, pembrolizumab and retifanlimab are all approved and none has been compared with another. First-line response was 39.7 per cent with avelumab in 116 patients, 56 per cent with pembrolizumab in 50 and 54.5 per cent with retifanlimab in 101. The retifanlimab study is the most fully reported: 17.8 per cent complete responses, median duration of response not reached in complete responders and 25.3 months in partial responders, median progression-free survival 16.0 months, and 63 per cent of patients alive at three years, in a disease where chemotherapy responses were measured in months. Grade 3 immune-related adverse events occurred in 10.9 per cent. Which antibody is used matters far less than that roughly half of patients respond and most responders keep responding. (POD1UM-201 (retifanlimab in advanced Merkel cell carcinoma), JAVELIN Merkel 200, KEYNOTE-017 (Cancer Immunotherapy Trials Network 09), Retifanlimab, Avelumab, Pembrolizumab, Immune-related adverse events (irAEs))
• What is available in England: NICE technology appraisal TA691 recommendation 1.1 recommends avelumab for metastatic Merkel cell carcinoma in adults who have not had chemotherapy for metastatic disease, under a commercial arrangement, on evidence collected in the Cancer Drugs Fund under TA517. TA517 recommendation 1.1 continues to cover its use after one or more lines of chemotherapy. Pembrolizumab and retifanlimab have no NICE appraisal for this disease. (Avelumab, Pembrolizumab, Retifanlimab, JAVELIN Merkel 200)
• Immunotherapy-refractory: Platinum-etoposide chemotherapy (brief responses), radiotherapy, clinical trials (ipilimumab-nivolumab, T-VEC, adoptive T cells). (Platinum + etoposide (EP / CE), Ipilimumab, Talimogene laherparepvec)

From the standard of care recorded for this cancer; which apply depends on your stage and biomarkers. Ask which the team recommends and why.