Photodynamic therapy represents a modern method of cancer treatment, in which a special photosensitizer molecule is administered to the patient and the tumor is then illuminated with a specific light.[1] An international team of scientists, including two experts from the Slovak Academy of Sciences, revealed a new mechanism of targeted damage to cancer cells.[1] Using cutting-edge biochemical methods, they identified guanine bases in DNA, which are oxidized by this molecule when exposed to light.[1] The research results, published in the journal Nanoscale Horizons in 2025, provide the first evidence that a photodynamic agent can selectively target and destroy specific DNA structures in cancer cells.[1] This targeted approach enables more effective and gentle treatment of tumors.[1]