Kazuo Yoneyama

Evaluation of photodynamic therapy in gastric cancer

Twenty-eight patients with gastric cancer were treated by photodynamic therapy. Haematoporphyrin derivative was used as a photosensitizer and an argon dye laser as a light source. Histologically, all tumours were adenocarcinomas. On the basis of endoscopy, 17 cases were categorized as early-stage cancer and were classified as type IIc (10 lesions), Ha (three lesions), combined type IIc and type III (three lesions) and type I (two lesions). In 11 patients with advanced-stage cancer, endoscopy showed one case of Borrmann I, three of Borrmann II, six of Borrmann III and a single case of Borrmann IV. In the 17 patients with early-stage cancers (18 lesions), complete remission was obtained in 10 patients (11 lesions). Of 13 resected cancers complete remission was confirmed in six lesions on the basis of detailed histological examination of resected specimens. In the advanced stage tumours all 11 patients showed incomplete remissions. It is considered that an incomplete response in the early-stage cancers is due to insufficient light dosage because of the wide area of tumour, because the site of the lesion is anatomically difficult to photoradiate and because the invasion extends to the muscular layer and serosa.

Photoradiation Therapy with Hematoporphyrin Derivative and an Argon Dye Laser of Bladder Carcinoma

Hematoporphyrin Derivative (HpD) which has an affinity for malignant tumors is excited by light exposure and reacts photodynamically in tumor tissue. Therefore it is possible to treat malignant tumor selectively without any damage to surrounding normal tissues. HpD is excited by a light in the spectrum from ultraviolet to visible red. Previously arc lamps and slide projectors were used for excitation of HpD but laser beams which facilitate photoradiation via endoscopes has been used recently. Much of the early basic and clinical studies on HpD and light photoradiation therapy was performed by Dougherty and his coworkers1. Hayata et al. investigated photoradiation therapy using an argon dye laser following an intravenous HpD administration in mice, and on cultured human lung cancer cells2, and in experimentally induced canine lung cancer and demonstrated its therapeutic effectiveness3. Malignant bladder tumor were treated by this new technique in this study.

CYTOMORPHOLOGICAL CHANGES CAUSED BY PHOTODYNAMIC THERAPY WITH HpD

Laser photodynamic therapy (PDT) with homatoporphyrin derivertive has been given increase attation. Many investgators have recognized that PDT is an effective local treatment of eraly stage cancer. To clarify experimental and clinical effectiveness due to PDT, a bronchofiberscopic brushing cytology was performed chronologically. The change of cellular components were studied by means of a phase contrast microscopic system and electron microscopy. The initial changes, halting of cellular movement, the degeneration of mitochondria, endoplasmic reticulum, and decrease of free ribosome. were recoanized.