Background and study aims: The fractionated application of laser light has been shown to enhance the effect of photodynamic therapy (PDT) on normal rat colon after photosensitization with 5-aminolevulinic acid. In a pilot study, we examined whether this modified laser treatment can also enhance the effect of PDT in patients with esophageal cancer after sensitization with hematoporphyrins.
Patients and methods: Six patients (four cases of early esophageal carcinoma and two cases of advanced esophageal carcinoma, one of the latter patients having tumor overgrowth on a metal stent) were treated in nine sessions. In four sessions, laser energy was fractionated to enhance the PDT effect using a hematoporphyrin polyester. Irradiation was carried out 48 hours after sensitization. The total laser energy of 150 J/cm2 was applied either continuously or in fractions, with a single break of five minutes after 75 J/cm2.
Results: Among the three patients who underwent continuous laser light irradiation, one patient experienced a complete remission of two of three superficial esophageal cancers. The patient with tumor overgrowth on an implanted metal stent showed a partial response, with improvement of dysphagia without destruction of the stent, while in another patient with advanced esophageal cancer, the dysphagia did not improve after continuous laser treatment. Fractionated laser therapy led to complete remission in all three patients with early cancers, one of whom had failed to respond to previous treatment with continuous PDT. A partial remission was obtained in a fourth patient with a uT2 cancer who had also shown no remission after continuous PDT treatment. However, after fractionated laser therapy, three mild esophageal stenoses occurred, in comparison with none after continuous PDT.
Conclusions: Light fractionation during PDT improved the effectiveness of the treatment in a small number of patients, and increased side effects such as the occurrence of mild esophageal stenosis. This modified treatment can be a promising approach in the effort to reduce the dose of hematoporphyrins or other sensitizers required, and to avoid prolonged skin sensitization or local stenosis.