Conventional photodynamic therapy induces cancer cell death by using photosensitizing agents, which localize in tumours and activate with exposure to a specific wavelength of light. In recent years, low-dose and long-term photodynamic therapy (metronomic photodynamic therapy, mPDT) has shown promise in treating cancers (lat. carcinoma) in internal organs. The problem with mPDT is, however, is that because the light intensity is extremely low (1/1000 of the conventional method), the antitumor effect cannot be obtained if the light source shifts even slightly away from the tumour, making the illumination insufficient. Nevertheless, scientists at the Waseda University in collaboration with the National Defense Medical College, and the Japan Science and Technology Agency developed a new bioadhesive, wirelessly-powered light-emitting device which could better treat cancers in delicate organs.