PDT is increasingly being recognized as an attractive alternative treatment for various cancers. PDT requires a photosensitizing drug, light of a specific wavelength, and oxygen. Upon absorption of photons, the drug generates toxic singlet oxygen species that react with nearby lipids, proteins, and nucleic acids. The primary role of PDT is to kill cancer cells by inducing immune response, apoptosis, or necrosis). This relatively new therapy has attracted extensive clinical and research interest in the last ten years, and various new PDT drugs have entered clinical trials worldwide, including studies in head and neck, lung, brain, breast, liver, colon, and bladder cancers. The first-generation photosensitizing drug Photofrin® is US-FDA approved for PDT in human cancer patients. Using the FDA-approved drug, preliminary PDT studies in head and neck cancer show that patients with early stage cancers or early recurrences in the oral cavity and larynx tend to have an excellent response to PDT. PDT can be an effective alternative treatment for a select patient population with recurrent head and neck cancer that is refractory to standard local approaches. However, the FDA-approved drug, Photofrin, has several limitations including skin burns, its short absorption wavelength, and serious side effects, which argues for the need to develop better tolerated approaches.
Imaged guided photodynamic therapy of head and neck cancer