Displacement of the prostate in the pelvis is one of the aspects that negatively affect the quality of external-beam radiotherapy for prostate cancer. The interfractional movement accounts for errors during the treatment of the prostate due to systematic inaccuracies and anatomical changes in the pelvis caused by the physiological filling of the hollow organs. This article presents the results of personalized treatment planning and monitoring of the treatment volume position during conformal radiotherapy (3D CRT) of locally advanced non-metastatic prostate cancer. Material and methods. This method of radiation treatment pre-planning was first tested at the State Institution “Grigoriev Institute for medical Radiology NAMS of Ukraine” and is used for treatment planning in patients with locally advanced non-metastatic prostate cancer undergoing a course of external-beam radiotherapy, as well as to monitor the position of the treatment volume in the interfractional period. Results and discussion. Treatment efficacy was evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST v.1.1, 2009) based on CT findings, by assessing the response dynamics of the primary tumor, by determining the adverse effects of conformal external-beam radiotherapy (changes in the blood count, gastrointestinal and urinary disorders, as well as skin disorders) according to the Common Terminology Criteria for Adverse Events toxicity scale (CTCA 5.00, 2018). We considered specific negative reactions to radiation therapy from different organs and systems. Thus, in patients of the main group there was a slightly lower manifestation of hematological reactions in comparison with the control group: 9.5% in the main and 11.4% in the control. This difference, however, cannot be considered statistically significant, but it captures a certain trend. As for the radial epidermis, they did not develop infrequently in both groups (only 6.3% and 8.5% of cases). We should keep in mind that these undesirable effects could not and cannot be considered a limiting factor for radiotherapy. Radiation proctitis was significantly less in the main group than in the control group. Thus, in the case of individualized conformal therapy in patients, 15.8% of radiation proctitis was observed, and in the case of traditional therapy, this figure reached 28.6%. The difference of about 1.8 times is quite indicative (p = 0.0028, CP). Conclusion. The comparison was done with the method of conventional radiation therapy planning. Personalized conformal radiotherapy pre-planning demonstrated a significant increase in tumor regression from 51.0% to 74.7%. Besides, a significant decrease was recorded in the frequency of the most common and burdensome toxic effects of treatment – radiation cystitis and proctitis, 39.6% in the study group versus 71.4% in the control group.
Keywords: prostate cancer, conformal external beam radiation therapy, radiotherapy planning, target volume
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