The timing has been optimized of photodetection (and possibly also phototherapy) of early cancer in the upper aerodigestive tract and bronchi and the relative concn. of fluorescent components of Photofrin II measured in patients as a function of the time after i.v. injection. In most cases, the measurements have been made on the tumor, neighboring normal tissue, and distant skin. The obsd. kinetics will be correlated in the future, among other parameters, with the staging of the early cancer, in particular, with its degree of vascularization.