Background: Endoscopic mucosal resection (EMR) was originated to treat early gastric cancer (EGC). EMR was suitable
for small, mucosal and well-differentiated adenocarcinoma without ulceration. It was difficult to resect larger tumors en
bloc by this method. In recent years, a more useful method, endoscopic submuscosal dissection (ESD) has been
developed, which enables en bloc resection of large mucosal lesions. On the contrary, photodynamic therapy (PDT) is
applicable to submucosal, poorly differentiated, or carcinoma with ulceration. In the era of ESD, we evaluated the value
of Photofrin-PDT. Patients & Methods: We applied PDT to 36 patients including three advanced cancers, who had been
excluded from EMR (ESD) and were at high risks for surgery or refused surgery. Four EGC patients who had not been
cured by EMR (ESD) were included. Our PDT procedure consisted of polyhematoporphyrin ether/ester administration
(Photofrin, 2 mg/Kg) and pulsed excimer dye laser irradiation at 630 nm 48 hours (and 96 hours) after sensitization.
Results: Complete response (CR) at three months was obtained in 84% (21/25) of mucosal cancer and in 50% (4/8) of
submucosal cancer. Although three patients with an advanced cancer improved but were not cured, quality of their life
was maintained. There were no serious side effects except skin photosensitivity. Conclusion: Photofrin-PDT should be
applied not only EGC patients who are excluded from ESD and have not been cured by ESD with poor risk for surgery,
and have high possibilitiy to be cured by PDT, but also advanced cancer patients for local improvement of lesions.
By rotating the optical axis of a nonlinear optical crystal ((beta) -BaB2O4), a tunable laser beam could be obtained from an optical parametric oscillator (OPO) laser. When the crystal was optically pumped by the third harmonics of the 1064 nm Nd:YAG laser, we had a coherent beam from 410 nm through 2550 nm continuously without changing the optical cavity. We compared photodynamic therapy (PDT) effects of two photosensitizers, phenophorbide a(Phd) and Photosan-3(Ph-3, hematoporphyrin-polyester), on Wistar rat liver. Twenty-four hours after sensitization (5 mg/kg i.v.), 670 nm and 630 nm light (75 mW/cm2) was irradiated for Phd and Ph-3 respectively at energy doses of 25, 50, and 100 J/cm2. The rats were sacrificed 24 hours after laser irradiation and analyzed pathologically. Phd produced more severe necrosis than Ph-3. Twenty-five J/cm2 of Phd was identical with 100 J/cm2 of Ph-3. Next, we treated HeLa cell tumors of nude mice by Phd 670 nm PDT and Ph-3 630 nm PDT. The PDT effects of the two photosensitizers on HeLa cell tumors were similar to those on normal liver tissue. In conclusion the OPO laser could make it possible to compare PDT effects of photosensitizers by activating them with their matched wavelengths.