Why Treating Beyond the Tumor Is the Key to Long-Term Skin Cancer Prevention

In this most recent Dermatology Time Expert Perspectives episode, Neal Bhatia, MD, director of clinical dermatology at Therapeutics Clinical Research in San Diego, California, discusses how visible tumors are only one part of a patient’s skin cancer journey. The lesion a clinician can see represents just a fraction of the underlying damage, and treating only what is visible leaves patients at significant ongoing risk.

"No matter how good a clinician we are, there's still an iceberg effect of every tumor that we see — probably 10% or 20% of the visible tumor, and everything else is still under the microscope or under the hood," Bhatia said.

That subclinical burden, driven by cumulative UV exposure, can give rise to additional actinic keratoses and basal cell carcinomas over time. Bhatia used an analogy of termites to explain the rising risk of additional skin cancers: “You see one, there’s 10 more.... So, whatever is coming is the way of thinking about how you want to take care of what you see today. If we're not treating in a way that's preventative or at least aggressive to the field of damage, I think we're not being complete in our approach of treating what we see in front of us.”

PDT as Chemopreventive Strategy

For Bhatia, photodynamic therapy (PDT) occupies a unique position among treatment options—not merely as a lesion-directed modality, but as the closest thing dermatology has to a true chemopreventive agent.

"Photodynamic therapy, in this way of thinking, is probably the most effective chemo prevention agent we have," he said, noting the absence of FDA-approved chemopreventive strategies and declining patient interest in systemic retinoids.

By targeting the entire zone of UV-damaged skin, not just the confirmed tumor, PDT addresses both what is visible and what may be emerging. For patients with significant photodamage or a history of actinic keratoses, this field-directed approach offers a meaningful long-term advantage in reducing skin cancer risk.

Cosmetic Outcomes and the Case for Non-Surgical Treatment

PDT's appeal extends beyond oncologic efficacy. In cosmetically sensitive areas such as the face, chest, and dorsal hands, the modality delivers clearance of lesions while simultaneously improving the appearance of the surrounding skin.

"PDT has really good data with the reduction of not only the lesion count for actinic keratoses or the clearance of tumor, but also the improvement in the cosmetic subunits — the sallow skin, the wrinkling, the dyschromia — all of that gets improved," Bhatia noted. Both red and blue light PDT carry comparable cosmetic potential, a contrast to cryotherapy, which carries a meaningful risk of dyschromia.

For patients dealing with surgical fatigue or tumors in aesthetically sensitive locations, PDT offers what Bhatia describes as the opportunity to treat "a little bit more conservatively, but yet also thoroughly."

Completing the Algorithm

Bhatia frames field treatment not as optional, but as an obligation of comprehensive care. Adjunctive strategies, including retinoid serums, polypodium leucotomos extract, and diligent sun protection, help maintain the gains achieved with PDT. But the modality itself remains foundational.

"If we're not treating in a way that's preventative or at least aggressive to the field of damage," he concluded, "I think we're not being complete in our approach of treating what we see in front of us."

View the full series here.