Article says that to investigate and compare the pharmacokinetic profile and anti-cancer activity of fluorinated and iodinated photosensitizers (PSs), the 3-(1′-(o-fluorobenzyloxy)ethyl pyropheophorbide and the corresponding meta-(m-) and para (p-) fluorinated analogs (methyl esters and carboxylic acids) were synthesized. According to the authors, the nature of the delivery vehicle and tumor types showed a significant difference in uptake and long-term cure by photodynamic therapy (PDT), especially in the iodinated PS.