Intraoperative photodynamic therapy in the combined treatment of soft tissue sarcoma

Soft tissue sarcoma is a rare malignant neoplasm. Despite the improvement of surgical techniques, the rate of relapses of the disease remains high. The search for alternative methods of treatment is relevant.Purpose. To evaluate safety and effectiveness of intraoperative photodynamic therapy of sarcoma in soft tissues.Material and methods. Forty-four patients with soft tissue sarcoma were included in the study. Patients were divided into three groups. Group 1 (n = 10): soft tissue sarcoma of stage T2-3N0M0G1, surgical treatment and intraoperative photodynamic therapy. Group 2 (n = 17): soft tissue sarcoma of stage T2-3N0M0G2-3, surgical treatment and intraoperative photodynamic therapy. Group 3 (n = 17): soft tissue sarcoma of stage T2-3N0M0-1G2-3, combined treatment – preoperative light therapy, surgical treatment, intraoperative photodynamic therapy, neoadjuvant and adjuvant chemotherapy. Fluorescence spectrometry was performed to determine the degree of photosensitizer accumulation in tumor tissue. Treatment methodology: photosensitizer was injected 2.5–3 hours before the surgery. The tumor was removed with resection of adjacent muscles and healthy tissues. Then, laser irradiation of the tumor bed was made using “Latus” device. Radiation power was up to 2,5 W, power density was up to 0,28 W/cm2, radiation dose was up to 100 J/cm2. Follow-up ranged from 14 to 44 months.Results. The spectrometry has revealed that photosensitizer was accumulated predominantly in tumor tissue. There were no reactions to photosensitizer injection, no changes in the tumor bed as well as no increase in wound healing period after intraoperative photodynamic therapy.Within the observation period, all patients stayed alive. Relapses of the disease were registered in 38.7 % of patients: in Group 1 – 30 %, in Group 2 – 35.3 %, in Group 3 – 53 %. Of the 20 patients with primary diagnosed neoplasms, relapses were seen in 30 %. Of the 24 patients with previously recurrent neoplasms, 45.8 % had repeated relapses.Conclusion. Intraoperative photodynamic therapy is a safe and effective technique for treating soft tissue sarcomas; it is also the promising direction for research. A small number of observations, a variety of histological forms and stages of the disease make it difficult to assess the effectiveness of the discussed approach. Further studies of intraoperative photodynamic therapy are required.