Chronic radiation-induced injury (CRII) is a common complication after radiation therapy for pelvic malignancies. Resection surgery could be an optimal surgical approach when CRII is complicated by late complications. However, because of high incidence of postoperative complications like anastomotic leakage rate and mortality, doctors try to avoid performing surgical resection. In addition, there is sparse agreement on the types of surgery.

Previous study proved that anastomosis with at least one end of bowel without radiation damage can greatly reduce postoperative anastomotic leakage rate and mortality. And in Bacon surgery, primary anastomosis is not performed, and the anastomotic tension markedly reduced and the blood supply of anastomosis can be judged intuitively to improve the quality of anastomosis in the second stage of intestinal anastomosis to decrease the anastomotic leakage rate. Combining the advantages of proximally extended resection and two-stage anastomosis could minimize potential complications and maximize the therapeutic efficacy in theory, and a small sample prospective clinical study by the investigator have already preliminarily confirmed it. The investigator has also preliminarily proved that Parks surgery is safe and feasible for the treatment of late complications of CRII.

Therefore, this study aims to observe the safety and effectiveness of PE-Bacon surgery with Parks surgery as a control, in order to select more optimal surgical methods and provide a high-level evidence-based medical basis for patients with late complications of CRII.

Chronic radiation-induced injury (CRII) is a common complication after radiation therapy for pelvic malignancies. Compared with diversion surgery, resection surgery removes the damaged tissue completely to avoid the risks of recurrence and improve patients' outcome. Hence, resection surgery could be an optimal surgical approach when CRII is complicated by late complications. However, because of high incidence of postoperative complications like anastomotic leakage rate and mortality, doctors try to avoid performing surgical resection. In addition, there is sparse agreement on the types of surgery.

With the advances of surgical techniques and perioperative care, the morbidity and mortality of resection surgery has been decreased significantly. In addition, previous study proved that anastomosis with at least one end of bowel without radiation damage can greatly reduce postoperative anastomotic leakage rate and mortality. And in Bacon surgery, primary anastomosis is not performed, and the anastomotic tension markedly reduced and the blood supply of anastomosis can be judged intuitively to improve the quality of anastomosis in the second stage of intestinal anastomosis to decrease the anastomotic leakage rate. Combining the advantages of proximally extended resection and two-stage anastomosis could minimize potential complications and maximize the therapeutic efficacy in theory, and a small sample prospective clinical study by the investigator have already preliminarily confirmed it. And the investigator has also preliminarily proved that Parks surgery is safe and feasible for the treatment of late complications of CRII.

Therefore, this study aims to observe the safety and effectiveness of PE-Bacon surgery with Parks surgery as a control, in order to select more optimal surgical methods and provide a high-level evidence-based medical basis for patients with late complications of CRII.

Inclusion Criteria:

• 1. Patients aged 18-70 years;
• 2. Patients with Eastern Cooperative Oncology Group (ECOG) physical condition score of 0-2;
• 3. Patients with previous pathological diagnosis of pelvic tumors (Gynecology, prostate, urinary system);
• 4. Patients with a history of pelvic radiotherapy, at least 6 months from the end of the last radiotherapy;
• 5. Patients without recurrence or metastasis of primary tumor;
• 6. The late complications of CRII patients, such as deep rectal ulcer (VRS score >=3), rectal sigmoid colon stenosis, obstruction, chronic perforation, rectal necrosis, rectovaginal fistula, intractable anal pain caused by rectal lesions, intractable rectal bleeding which is still difficult to be relieved by stoma operation, and patients who need sigmoid colorectal resection;
• 7. Patients who can tolerate general anesthesia;
• 8. The subjects and their families are able to understand the study plan, willing to participate and sign the informed consent.

Exclusion Criteria:

• 1. Patients with acute intestinal obstruction, acute intestinal perforation and intestinal hemorrhage who need emergency operation;
• 2. Patients with severe pelvic adhesion and frozen pelvis;
• 3. Patients with unstable primary tumor or tumor in other parts;
• 4. Patients who need to undergo combined organ resection;
• 5. Patients with a history of sigmoidostomy;
• 6. American society of anesthesiologists (ASA) level IV to V;
• 7. Patients with serious mental illness;
• 8. Pregnant or lactating women;
• 9. Patients with serious cardiovascular disease, uncontrollable infection, or other uncontrollable combined diseases.