**4. Results**

We could not find information on the use of photodynamic therapy in children in the treatment of retroperitoneal tumors in the available literature sources. General and relapse-free survival of patients in the studied clinical groups was analyzed by the Kaplan-Meier method to assess the effectiveness of treatment results, regarding the percentage of patients who survived after the use of photodynamic therapy. The duration of observation time was from the intraoperative photodynamic therapy to the end of a 5-year follow-up. Based on the data obtained, the mean values of the survival time before the onset of death and mean values before the onset of relapse in patients of the control and study groups were obtained, as shown in **Tables 4** and **6**. The mean time free from any outcome (death, relapse) is a certain number of months, **Tables 5** and **7**. The tables also present standard error (SE) and 95% confidence interval (95% CI) values for the mean time value.

A graphical presentation of the Kaplan-Meier method was the curves of the overall 5-year and relapse-free survival, as shown in **Figures 1** and **2**. The ordinate axis shows the probability of outcome occurrence, and the abscissa axis shows time (months).


#### **Table 4.**

*Percentage of cases of fatal outcome in patients with tumor, depending on the treatment method.*


#### **Table 5.**

*Mean value of survival time before fatal outcome in the studied groups of patients.*


#### **Table 6.**

*Percentage of cases of relapse in patients, depending on the treatment method.*


#### **Table 7.**

*Mean survival time prior to relapse.*

**Figure 1.** *Overall 5-year survival rate of studied patients.*

**Figure 2.** *Comparison of relapse-free survival in studied patients.*

*Photodynamic Therapy in Complex Therapy of Retroperitoneal Tumors in Children DOI: http://dx.doi.org/10.5772/intechopen.101884*
