Photodynamic therapy and fluorescence diagnosis of skin cancers

Area of Science:

• Dermatology
• Oncology
• Photodynamic Therapy

Background:

• Porphyrin-sodium photodynamic therapy (PDT) is approved but restricted due to prolonged photosensitization.
• Topical 5-aminolevulinic acid (ALA) and its derivatives are promising photosensitizers in dermatology.
• ALA is a precursor of heme biosynthesis, showing efficacy in superficial skin cancers and precancerous conditions.

Purpose of the Study:

• To evaluate the efficacy and diagnostic potential of 5-aminolevulinic acid (ALA) in photodynamic therapy (PDT).
• To explore ALA's role in treating superficial skin cancers and precancerous conditions.
• To investigate ALA's utility in tumor visualization for diagnosis and surgical planning.

Main Methods:

• Systemic and topical application of 5-aminolevulinic acid (ALA).
• Photodynamic therapy (PDT) utilizing ALA as a photosensitizer.
• Fluorescence visualization of induced protoporphyrin IX in epithelial tumors using CCD camera and digital imaging.

Main Results:

• ALA-PDT demonstrates good clinical and cosmetic results for superficial skin cancers like basal cell carcinoma and actinic keratoses.
• Phase III studies confirm ALA-PDT efficacy in Bowen's disease and actinic keratoses.
• ALA induces protoporphyrin IX selectively in epithelial tumors, enabling visualization with high tumor-to-tissue ratio for diagnostic purposes.

Conclusions:

• ALA-PDT is an effective treatment for various superficial skin cancers and precancerous conditions.
• ALA's fluorescence properties offer a valuable tool for tumor diagnosis and surgical planning.
• Further prospective studies are assessing the routine employment of ALA-based fluorescence imaging systems.