Problems in laser therapy for gastric cancer and its future course

Abstract

We compared an Nd-YAG laser (Model 8000: 1064nm; Molectron Medical) and a high-power diode laser (Diomed 25: 805nm; Diomed) in terms of tissue damage and subsequent cellular proliferative activity. We made a fundamental study on an appropriate injection schedule of 5-FU for the purpose of achieving higher concentration of 5-FU within tumor tissue in laser photoradiation. [Method] i) The gastric mucosa of dogs was continuously photoradiated for 1, 2, 3 or 5 seconds at a power of 10W or 20W and with the transmission fiber either in contact or not in contact with the mucosa. Thermal necrosis of tissue was compared by HE stain. ii) Gastric ulcers were induced in rats by contact photoradiation (20W/1sec.). BrdU (50mg/Kg) was intraperitoneally injected 1, 3 or 7 days after photoradiation. Two hours later, stomachs were resected, and the labelling index (LI) compared. iii) Colon 26 cells were transplanted to the abdominal wall of BALB/c mice by intracutaneous injection. Tumors were treated by contact photoradiation (20W/1sec.). BrdU (50mg/Kg) was administered intraperitoneally 3 or 7 days later. Tumors were resected two hours subsequently, and the LI was compared. iv) BALB/c mice with 10 mm tumor (caused in the same way as iii) were intraperitoneally injected with 5-FU (50mg/Kg). And the tumors were treated by contact photoradiation (10W, 1sec./total dose of 100J) of diode laser. We set the groups of (1) Control, only with 5-FU injection, (2) FL with laser photoradiation 5min. after 5-FU injection and (3) LF with laser photoradiation 30min. before 5-FU injection. We measured intratumoral 5-FU concentration respectively.