Bauer and Graves16 and Bauer17,18 suggested that low concentrations of 1O2 from CAP, or derived through interaction of long-lived species in PAM, would interact with the surface of tumor cells, that carries NOX1, catalase and SOD, in the same way as shown before for extracellular 1O2 generated by a photosensitizer. Here, CAT is linked to neoplasm.