PHOTODYNAMIC THERAPY FOR OBSTRUCTING ESOPHAGEAL CANCER - LIGHT DOSIMETRY AND RANDOMIZED COMPARISON WITH ND-YAG LASER THERAPY

Background & Aims: Light dosimetry analysis to achieve predictable tumor necrosis has not been performed for photodynamic therapy (PDT) in the gastrointestinal tract. We evaluated dihematoporphyrin ethers for sensitizing esophageal carcinomas to 630 nm light and compared PDT with neodymium:yttrium-aluminum-garnet (Nd:YAG) laser therapy in a randomized trial. Methods: Of 52 patients with dysphagia, 32 received palliative PDT. Ten patients treated with PDT participated in a preliminary trial using various doses of 630-nm light, and 22 patients treated with PDT participated in a randomized trial using a derived standardized light dose for comparison with 20 patients treated with the Nd:YAG laser. Results: Light dosimetry correlated with depth of tumor necrosis (r = 0.664; P < 0.001). PDT activity was similar for squamous cell and adenocarcinoma. Among randomized patients, both PDT and Nd:YAG therapy relieved dysphagia, but PDT resulted in improved Karnofsky performance status at 1 month (+7 vs. -7; P < 0.001) and longer duration of response (84 vs. 57 days; P = 0.008). Skin photoreactions were unique to PDT. Conclusions: The extent of PDT tumor ablation correlates with light dosimetry, enabling selection of a standardized light dose. PDT can relieve esophageal obstruction from squamous cell and adenocarcinoma and is an alternative to Nd:YAG thermal necrosis with a longer duration of response. However, PDT requires patient precautions to minimize skin photoreactions.