Photodynamic Therapy for Keratinocytic Precancerous Lesions and Non-Melanoma Skin Cancer: A Narrative Review.

Photodynamic therapy (PDT) is a cornerstone non-invasive modality for keratinocytic precancers and non-melanoma skin cancer (NMSC), leveraging selective photosensitizer accumulation, light activation, and reactive oxygen species (ROS) generation. This narrative review synthesized literature from major databases (2010-2025) to comprehensively evaluate PDT's molecular mechanisms, innovative optimization protocols, and clinical efficacy across actinic keratosis (AK), field cancerization, Bowen's disease (BD), basal cell carcinoma (BCC), and invasive squamous cell carcinoma (cSCC). The evidence highlights frontline clinical maturity and excellent cosmetic outcomes for superficial lesions (AK, field cancerization, superficial BCC, and BD), with daylight PDT offering a virtually painless alternative for widespread dysplasia. However, therapeutic reliability decreases in thick nodular, pigmented, or high-risk lesions due to optical barriers and tissue hypoxia. To overcome these limitations, advanced physical and chemical enhancements-such as ablative fractional lasers, iron chelators, epigenetically enhanced PDT (ePDT), and targeted nanocarriers-are actively reshaping drug delivery and cellular susceptibility. Furthermore, cyclic PDT serves as an indispensable tissue-sparing intervention for organ transplant recipients and Gorlin syndrome patients. In conclusion, while PDT is highly effective for superficial neoplasias, precise histopathological stratification and the integration of nanomedicine are critical to overcoming current biological barriers in aggressive dermatological malignancies.