This study is to explore the progression-free survival time (PFS) , overall survival time (OS), quality of life and side effects between two different clinical target volumes in the treatment of 3D printing template-assisted CT-guided radioactive iodine-125 seeds implantation for recurrent rectal cancer after surgery and radiotherapy and investigate the clinical and dosimetric prognosis factors for outcomes.

From June 2019 to December 2020 in each participating center, patients with recurrent rectal cancer after surgery and radiotherapy will be included in the study if they meet the inclusion criteria and do not meet the exclusion criteria. According to the clinical conditions of the patients, they will be assigned to groups A or B according to the doctor's recommendations and their own wishes. GTV of both groups are visible tumors. The CTV of group A is expanded by 3mm on the basis of GTV, and the CTV of group B is expanded by 6mm. Both groups A and B received prescription dose: 95% GTV (120-160) Gy, 95% CTV (90-120) Gy. The activities of 125I seeds will be 0.4mCi-0.7mCi. All patients will receive 3D printed template-assisted 125I seeds implantation and be followed up. The differences in local progression-free survival time, overall survival time, change of quality of life, and side effects between different groups will be prospectively analyzed.

Inclusion Criteria:

• KPS score above 60;
• Age from 18 to 80 years old;
• Rectal cancer by histological diagnosis, recurrence after surgery and radiotherapy;
• The diameter of the lesion ≤ 5cm;
• The tumor has not invaded the intestines or bladder;
• The estimated survival time is more than 3 months;
• The percutaneous puncture path is feasible and the preoperative plan can meet the prescription dose;
• Blood routine, liver, kidney and other major organ functions: WBC is normal, PLT≥100×109/L, HGB≥100g/L; urea nitrogen, creatinine≤1.25×upper limit of normal (UNL), ALT (SGPT) and AST (SGOT) ≤2.5×UNL; ECG is basically normal;
• Recurrence in pelvic region after surgery and radiotherapy for various reasons; or oligo-metastatic lesions less than 3, which are stable with treatment. Except for rectal incision stump and recurrence at the anastomosis.

Exclusion Criteria:

• Major organ failure, decompensated heart and lung failure such as congestive heart failure, coronary heart disease with clinical symptoms, and arrhythmia that cannot be controlled by drugs;
• Patients with other serious uncontrollable medical diseases;
• Severe coagulation dysfunction;
• With serious infection or ulcer at the puncture site;
• Pregnancy, breastfeeding women, children and mental patients;
• Patients with severe diabetes;
• Cases that invade large blood vessels and vital organs, which may cause hemorrhage and severe organ dysfunction;
• Those who have participated in clinical trials of other drugs or medical devices before being selected but have not reached the time limit of the main research endpoint or have completed clinical trials of other drugs or medical devices for less than 4 weeks;
• Poor compliance and unable to complete the course of treatment;
• Other reasons the researchers think it is inappropriate to participate in this clinical trial.

Recurrent rectal cancer after surgery and radiotherapy who will receive 3D-PT Assisted CT-guided I-125 Seeds Implantation