Skin Cancer
Melanoma and non-melanoma skin cancers, almost all linked to UV exposure.
Last revised
Key takeaways
- ABCDE: Asymmetry, Border, Colour, Diameter, Evolving
- Most important feature: change over weeks or months
- Most useful single change: Check your skin periodically and ask someone to check your back.
- Commonest mistake: Sunbeds.
- See a doctor if any of the signs under "When to get help" below apply to you.
Why it matters
Melanoma found early is usually curable by simple excision, and found late it is not.
The numbers, in one place
| Measure | Figure |
|---|---|
| ABCDE | Asymmetry, Border, Colour, Diameter, Evolving |
| Most important feature | change over weeks or months |
| Non-melanoma sign | a sore that does not heal in 4 weeks |
| Sunscreen | at least SPF 30 with 4-star or 5-star UVA |
| Sunbeds | raise risk and are never a safe option |
What helps
- Check your skin periodically and ask someone to check your back
- Photograph anything uncertain to compare later
- Use shade and clothing first; sunscreen is the last line
- See a GP about change rather than appearance alone
What to avoid
- Sunbeds
- Waiting to see whether a changing lesion settles
- Relying on apps to decide whether a mole needs checking
Where to go next
- Popular Beliefs About Skin Cancer, and What Is Actually Published
- New to Skin Cancer? Start Here
- Bowel Cancer: Sorting the Evidence From the Noise
- Breast Cancer: Sorting the Evidence From the Noise
When to get help
See a GP promptly about a mole changing in size, shape or colour, with an irregular edge or more than one colour, larger than 6mm, or itching, bleeding or crusting. Also report any sore, lump or scaly patch that has not healed within four weeks.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarised or generalised beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.