What if the rough, scaly patch you freeze in clinic today is just the visible part of widespread sun damage? Treating only what you can see may mean missing the bigger risk.

We explore how recognising and treating the entire sun-damaged area reducing progression to squamous cell carcinoma and improve long-term outcomes.

I’m joined by dermatologist and Mohs surgeon Dr Chin-Yun Lin, who shares practical, primary care–focused guidance on choosing and using field therapies for actinic keratoses.

Using the case of Simon, a 55-year-old builder with significant sun exposure and multiple lesions on his face and hands, we discuss:

1. What “field treatment” really means in everyday general practice
2. When to move beyond spot cryotherapy and treat the whole area of sun damage
3. How to choose between topical 5-fluorouracil, imiquimod, and photodynamic therapy
4. Preparing patients for treatment reactions and improving adherence
5. When to refer and when you can confidently manage in primary care

This episode is full of practical tips to help you manage sun-damaged skin more effectively and reduce your patients’ long-term skin cancer risk.

Practical clinical pearls :

1. Patient Education is Key: Reinforce sun protection, ongoing self-examination, and adherence.Explain that AKs are precancerous, not benign warts—early treatment reduces risk of SCC.
2. Preparation of the Skin Improves Efficacy: Gentle debridement, keratolytic creams (urea or salicylic acid), or low-potency retinoids before topical therapy can enhance penetration and response.
3. Field Treatment is Often Preferable for Multiple Lesions: When you see multiple AKs or “field cancerization,” topical therapies (like 5-fluorouracil, imiquimod, or diclofenac) can treat visible and subclinical lesions simultaneously.Pick therapy based on patient tolerance, adherence, and skin location.
4. Treatment Selection Depends on Lesion and Patient Factors:5-FU: aggressive but effective, may cause intense inflammation—good for thicker or widespread AKs. Imiquimod: immune-stimulating, good for thinner AKs or for patients who prefer intermittent dosing. Photodynamic therapy (PDT): alternative if topical therapy fails or not tolerated.
5. Monitor for Flare or Incomplete Response: Mild irritation is expected, but severe inflammation, erosion, or ulceration may require pausing treatment. Non-responding lesions should be reevaluated for biopsy, as persistent AK may hide squamous cell carcinoma (SCC).
6. Refer to a dermatologist: if the diagnosis is unclear, or if the lesion requires expert excision or specialized management.

Resources:

https://www.rnzcgp.org.nz/events/ongoing-events/gp-dermatology-course/

https://dermnetnz.org/topics/actinic-keratosis

https://dermnetnz.org/cme/lesions/topical-treatment-of-photodamage

https://dermnetnz.org/topics/5-fluorouracil-cream

https://dermnetnz.org/topics/imiquimod

Guest bio:

Dr Chin-Yun Lin is a Dermatologist and accredited Mohs micrographic surgeon. His specialty interests include the treatment of skin cancer, melanoma, dermatitis, psoriasis, acne, pigmentary disorders, and cosmetic dermatology.

After graduating as Dux of Macleans College in Auckland, he went on to complete his undergraduate medical degree with first-class honours at the University of New South Wales in Australia.

He undertook Dermatology advanced training at tertiary teaching hospitals in Auckland, Hamilton, and Christchurch. Further Dermatology training and a Mohs surgical fellowship were undertaken at St Vincent's Hospital and the Skin Hospital in Sydney. He is also a Fellow of the American College of Mohs surgery.

Dr Lin has won various Dermatology awards such as the Trans-Tasman Scholarship for best registrar presentation at the New Zealand Dermatological Society Annual Conference, and the best poster presentation at the Australasian College of Dermatologists Annual Scientific Meeting.

Dr Lin also takes interest in clinical teaching and research. He is a registered education provider for the RNZCGP. He has published several papers in peer-reviewed journals, and presented at international conferences such as the World Congress of Dermoscopy. He has written a practical course for GP’s on dermatology- link in resources.

Dr Lin has also served on the reviewers’ panel for the Australasian Journal of Dermatology.

Email me:

thespecialistgp@outlook.co.nz

Listen here:

Apple : https://podcasts.apple.com/nz/podcast/field-treatments-in-sun-damaged-skin-w-dr-chin-yun-lin/id1845748299?i=1000755425551

Spotify: https://open.spotify.com/episode/3CPztsA04YtvzodwM7s2AI?si=c3ed7ee2635f4f83