Hematoporphyrin is primarily used in photodynamic therapy (PDT) for cancer treatment. It acts as a photosensitizer, accumulating in cancer cells and becoming activated when exposed to specific wavelengths of light. This activation generates reactive oxygen species that destroy the targeted cancer cells. It is particularly effective in treating skin cancers, esophageal cancer, and bladder cancer. Additionally, hematoporphyrin is utilized in diagnostic imaging to detect malignant tissues due to its fluorescence properties under certain light conditions. Its ability to selectively target abnormal cells makes it a valuable tool in both therapeutic and diagnostic applications.