Clinical trial of photodynamic therapy using acridine orange with/without low dose radiation as new limb salvage modality in musculoskeletal sarcomas.

Most patients with musculoskeletal sarcoma do not recover satisfactory limb function after limb salvage surgery. To achieve satisfactory improvement of limb function, we developed a unique surgical modality of photodynamic therapy using acridine orange (AO-PDT) and clinically applied it to patients with musculoskeletal sarcomas. Ten patients with primary musculoskeletal sarcomas were enrolled in the study. Of these, 6 had primary malignant soft tissue sarcoma and 4 had primary malignant bone tumor. In the AO-PDT procedure, intralesional or partially marginal tumor excision was initially conducted and microscopic curettage of the remnant tumor, which emitted green fluorescence under blue excitation after local administration of 1microg/ml AO solution, was performed using a fluorescence surgical microscope. Subsequently, blue light illuminated there for 10 minutes. The surgical wound was closed, followed by immediate X-ray irradiation of the resected area with 5 Gy in 5 out of 10 patients to enhance the effect of AO-PDT. The follow-up of the patients ranged from 24 to 48 months. All the patients (AO-PDT alone: 5, AO-PDT with 5-Gy radiation: 5) are alive; only one patient showed local recurrence of the tumor. The recurrence rate was 10%. None of the 5 patients treated by AO-PDT with radiation developed local tumor recurrence. The limb function in all the patients, except for one, recovered to the level before surgery. None of the patients clinically showed any local or systemic complications. AO-PDT may be a promising new limb salvage modality for preservation of excellent limb function in patients with musculoskeletal sarcoma.