Evaluation of the rectal V30 parameter in patients diagnosed with postoperative endometrial cancer

BACKGROUND: The present paper reports on analysis of 184 patients who were diagnosed with endometrial cancer. The main objective of this study was to address parameter V(rec(30Gy)) which determines a volume of the rectum irradiated with a dose of 30 Gy during radiotherapy. MATERIALS AND METHODS: All patients were irradiated with an IMRT technique on linear accelerators. The planning target volume (PTV) contour was determined by a radiation oncologist. The clinical target volume (CTV) was drawn on CT images obtained in a prone position. For statistical analysis, appropriate tests (e.g. the Shapiro-Wilk, Wilcoxon) were used. RESULTS AND DISCUSSION: The performed analysis showed that the recommended condition for V(rec(30Gy)) is met only in 3% of patients and the observed median value exceeds 90%. The obtained results were compared with the studies in which the V(rec(30Gy)) values were related to various radiotherapy techniques. CONCLUSIONS: The analysis showed that the condition for V(rec(30Gy)) is satisfied in the case of only 3% of patients. Due to the difficulty with meeting the condition, it should be reconsidered based on real results.