**6. Conclusions**

The proposed method of complex treatment of retroperitoneal tumors using PDT allows improvement of the results of surgical treatment; it significantly increases the survival rate of patients with retroperitoneal tumors (91.3% vs. 74.5%) (p < 0.050). Thus, PDT is a promising antitumor strategy, technically possible, and can be successfully used in the complex therapy of retroperitoneal tumors in children.
