Currently, the limiting factor in cancer chemotherapy is still the lack of selectivity of anticancer drugs towards neoplastic cells. Photosensitizers (PS), the active com pounds used for photodynamic therapy (PDT), have the intrinsic advantage of dis tributing primarily in highly regenerative tissues after intravenous or topical ad ministration. Therefore, they will accumulate preferentially in tumor tissue when present. In addition, these molecules are inactive as such; indeed, the anticancer effect is only attained after irradiation with light at the right wavelength. Compared to other current cancer therapies such as surgery, radiotherapy or chemotherapy, PDT is an effective and selective means of suppressing diseased tissues without altering the surrounding healthy tissue. It also offers a unique opportunity to reach unseen metastasis. As fluorescent molecules, PS may also be used as a tool, namely photodetection (PD), to reveal tum.or tissues that remain unseen by other conventional methods.