In 1995, Porfimer sodium, a light-sensitive drug that can be absorbed by tumors, was approved by the U.S. Food and Drug Administration (FDA), permitting photodynamic therapy of some types of cancer.

A randomized, comparative trial (236 patients) using a Nd-YAG laser for treatment of partially obstructing esophageal cancer, indicated similar relief of dysphagia in both arms, a longer lasting tumor response for PDT (32% at 1 month versus 20% for Nd-YAG), and more complete responses (negative endoscopic biopsies) for PDT than for Nd-AG (9 versus 2) Dougherty et al (1998).