EXPERIMENTAL STUDY ON THE INHIBITION EFFECT FOR LOCAL RECURRENCE AFTER INTRALESIONAL EXCISION OF OSTEOSARCOMA USING PHOTODYNAMIC THERAPY WITH ACRIDINE ORANGE

Aomori K¹⁾, Kusuzaki K¹⁾, Suginoshita T¹⁾, Hashiguchi S¹⁾, Murata H¹⁾, Takeshita H¹⁾, Ashihara T²⁾, Hirasawa Y¹⁾, (Department of Orthopaedic Surgery, and Pathology, Kyoto Prefectural University of Medicine, Kyoto, Japan)

If intralesional excision could be applied to osteosarcoma, satisfactory limb function and a higher quality of life could be achieved. Therefore, we experimentally examined the effectiveness of intralesional excision for osteosarcoma using photodynamic therapy (PDT) with acridine orange (AO), an agent with vital staining fluorescence and anti-tumor effects. The experimental osteosarcoma model consisted of cultured mouse osteosarcoma cells (MOS) that were subcutaneously inoculated in the back of C3H mice. Two hours after intraperitoneal injection of 10mg/kg AO to mice with tumors (ø8mm), intralesional tumor excision (curettage) was performed and then minimal residual tumor tissue emitting green fluorescence of AO by excitation with blue light was additionally excised After 10 minutes of PDT, the local tumor recurrence rate within 3 months was evalutated in comparison with control groups. The results showed that the recurrence rate of the PDT and double curettages group was 23%, whereas that of the non-PDT group with one curettage was 80%. A significant difference was found between these groups (p<0.01). The recurrence rate of the non-PDT group with double curettages was 40% and that of the PDT group with one curettage was 50%. Our in vivo results suggested that PDT and an additional curettage under tumor visualization with AO effectively inhibited local tumor recurrence in osteosarcoma. This intralesional excision technique may be useful to obtain satisfactory limb function in osteosarcoma patients.