Abstract
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.
