Following the UK’s hottest summer on record, with UV levels reaching as high as 8—where unprotected skin can burn in as little as 15 minutes—dermatologists are emphasizing the importance of recognizing and treating sun damage to prevent skin cancer.

While public awareness commonly focuses on monitoring moles for changes, experts highlight several other signs that warrant medical attention. These include non-healing crusted or bleeding areas, which may indicate basal cell carcinoma (BCC), the most frequent type of skin cancer, and tender, warty nodules often found on sun-exposed areas like the ears, lips, or scalp, which could signal squamous cell carcinoma (SCC).

In addition to visible cancers, clinicians now give greater attention to widespread sun damage known as “field cancerisation.” This condition involves large areas of the skin where chronic ultraviolet (UV) exposure has altered cells, increasing the risk of developing cancer across the region rather than just at isolated spots. Dermatologists refer particularly to actinic keratoses (AKs), dry, red, scaly patches that appear on sun-exposed sites such as the face, scalp, neck, and chest. Although AKs represent early cellular abnormalities restricted to the upper skin layer, they can progress to SCC if left untreated.

Treatment often begins with cryotherapy—freezing the AKs with liquid nitrogen. However, clinicians caution against focusing solely on obvious lesions. Research published in 2018 found that AKs adjacent to invasive SCC often appear less severe or subclinical, making them easy to overlook. This has prompted increased advocacy for “field treatment,” where the entire affected area, not just visible lesions, is treated to remove or control damaged cells across the skin. Although countries such as Australia and the United States officially recommend this approach, guidelines in the UK remain less definitive, with the National Institute for Health and Care Excellence (NICE) only advising that field treatment be considered.

One common method for field treatment involves the chemotherapy cream 5-fluorouracil (5-FU), applied up to twice daily for up to four weeks to destroy rapidly dividing damaged cells. Treatment can be uncomfortable and cosmetically challenging, causing redness and crusting that may limit patients’ social and professional activities. Recent developments have combined 5-FU with topical vitamin D (calcipotriol), which appears to accelerate treatment, reducing it to as few as four days on the face. The vitamin D component stimulates an immune response, recruiting T-cells that target abnormal cells, potentially providing longer-lasting surveillance against new skin damage. Studies have demonstrated that this combined treatment reduces the incidence of facial SCC compared with 5-FU alone. Although not yet approved for routine use by the NHS, dermatologists can prescribe it off-label pending further clinical trial results.

Another treatment gaining traction is daylight photodynamic therapy (PDT). This involves applying a photosensitizing cream containing aminolevulinate derivatives followed by exposure to natural or artificial light, which selectively destroys damaged skin cells. Beyond reducing SCC risk, daylight PDT has shown notable cosmetic benefits, improving skin texture, color uniformity, and reducing fine lines and thread veins. Combining PDT with fractional laser technology—which enhances skin permeability—may further enhance effectiveness.

In addition to clinical benefits, field treatments often lead to behavioral changes in patients, such as increased use of sun protection measures like high-SPF sunscreen and hats. Many patients report seeing field treatment as an opportunity for renewal, motivating them to adopt safer sun habits and maintain healthier skin over time.