PET-CT for Skin and — Merkel Cell Cancers

For most people with basal cell carcinoma, PET-CT is not needed. Basal cell carcinoma almost never spreads to distant organs, so a whole-body scan adds little to management. Treatment is usually surgery or radiation guided by clinical examination and local imaging. In the rare case where the tumour is locally advanced or has returned repeatedly, your oncologist may consider it. If a PET-CT has not been mentioned, it is most likely because it is not indicated for your situation.

A bright area means that part of the body is taking up more glucose than the surrounding tissue, which can indicate active cancer — but not always. Inflammation, infection, a healing wound, and some benign conditions also cause increased uptake. Your oncologist will interpret the finding alongside your clinical picture and biopsy results. A suspicious area may prompt further investigation, such as a biopsy, rather than an immediate change in treatment.

CT shows anatomy — the size and shape of lymph nodes and organs. PET adds a metabolic layer — it shows whether cells in those structures are consuming glucose at an elevated rate. Combining both lets the specialist see anatomy and activity together. For Merkel cell carcinoma, this matters because the metabolic component can detect disease in lymph nodes that have not yet grown large enough to look abnormal on CT alone.

It is not the preferred test for brain metastases. The brain consumes glucose at a high normal rate, which can mask small deposits and make them difficult to distinguish from background activity. MRI of the brain is more sensitive for this purpose and is what your team would order if brain involvement is suspected. In advanced disease, PET-CT and brain MRI are often ordered together — each covering the weakness of the other.

NCCN guidelines include PET-CT as part of surveillance after initial treatment for Merkel cell carcinoma, because MCC has a higher recurrence rate than most skin cancers and can return in distant sites. The frequency depends on your stage, your response to treatment, and how long you have been in remission — there is no single schedule that applies to everyone. At CION, PET-CT is coordinated with partner imaging centres, and your follow-up plan is reviewed at each clinic visit.

PET-CT involves a modest dose of ionising radiation from both the CT component and the radioactive tracer. For most adults being investigated or monitored for cancer, the benefit of the information it provides outweighs this exposure. The tracer is cleared from your body through your urine over several hours. If you are pregnant or think you may be pregnant, tell your team before the scan is arranged. If repeated scans are needed over many years, your oncologist will discuss cumulative exposure with you.