L. Ma; Peking University First Hospital, Beijing, Beijing, China
Purpose/Objective(s): Due to differences in radiotherapy technology and quality control levels, the margin of prerectal PTV is not consistent among centers. Based on a strict quality control plan, our center’s PTV margin on posterior prostate is 0mm. This study conducted a retrospective analysis on whether this precise and individualized prerectal PTV range can reduce rectal side effects without affecting the efficacy. Materials/
Methods: We retrospectively analyzed 189 patients who underwent limited-stage prostate cancer from January 2016 to January 2020. We selected patients with limited-stage prostate cancer who had completed the entire course of radical radiotherapy in our center. Patients with the following conditions were excluded:? Pathology report shows tumors other than prostate adenocarcinoma (such as prostate sarcoma, neuroendocrine cancer); ?Combined with other malignant tumors; ? Incomplete clinical medical records. ?The tumor has invaded the rectum.From 2016 to 2020, all radical radiotherapy for prostate cancer in our center adopts strict registration under daily image-guided radical radiotherapy (Daily-IGRT). The posterior boundary of PTV is the anterior rectal wall of the patient, and the rectum is removed from the PTV. Our median dose and median fraction of PTV is 6750cGy/25f. Prophylactic radiation of the lymphatic drainage area is determined by the risk stratification of the patient. Results: In this retrospective study, we have completed the follow-up of 189 patients with a median follow-up time of 48.6 months. These patients all completed the full of Daily-IGRT for prostate cancer at our center. Only 1 of 189 (0.53%) patients developed local tumor recurrence. the patients 5-year OS was 90.7%, the 5-year PFS was 81.2%, and the 5-year bPFS was 72.9%. patients’ grade =2 acute genitourinary (GU) toxicity is 18.4%, acute gastrointestinal(GI) toxicity is 13.5% . And patients’ grade =2 late GU toxicity is 7.3%, and late GI toxicity is 5.9%. The toxicity were all lower than most internationally Research. In our center, under strict registration of daliy IGRT, which will not reduce the recurrence rate and reduce side effects. Conclusion: Our personalized PTV expansion model for prostate cancer is based on precise planning design and Daily anterior rectal wall registration, which can significantly reduce side effects without affecting clinical efficacy.
