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Field Cancerisation — SCE Dermatology MCQ

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ModerateSkin CancerField CancerisationSCE Dermatology

A 60-year-old man has extensive actinic damage with multiple actinic keratoses covering his entire scalp (field cancerisation). His dermatologist plans to treat the entire field rather than individual lesions. What is the rationale for field treatment?

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Correct answer: C — Field treatment addresses both visible AKs AND subclinical dysplastic keratinocytes in the surrounding photodamaged skin that are invisible clinically but represent early lesions that will become visible AKs or progress to SCC

Field cancerisation refers to the concept that UV-damaged skin surrounding visible AKs contains widespread subclinical keratinocyte dysplasia (genetically altered cells not yet visible as clinical AKs). Treating only visible individual lesions leaves the subclinical field untreated, resulting in high rates of new AK development. Field-directed therapies (topical 5-FU, topical Imiquimod, PDT, topical Diclofenac, topical Tirbanibulin) treat the entire photodamaged area, destroying both visible AKs and subclinical dysplastic cells. This reduces the total AK burden and may decrease SCC progression risk. The choice of field therapy depends on: area size, patient tolerance, cosmetic expectations, and whether the patient is immunosuppressed.

Reference: BAD 2017 AK Guidelines; NICE