JCOG1801 is a randomized phase III trial which was initiated in Japan in August 2019 to confirm the superiority of preoperative chemoradiotherapy followed by surgery plus adjuvant chemotherapy for local relapse-free survival over standard treatment, i.e. surgery plus adjuvant chemotherapy, for previously non-irradiated locally recurrent rectal cancer.

In all, 110 patients from 43 Japanese institutions will be recruited over a period of 6 years. Eligible patients would be registered and randomly assigned to each group with an allocation ratio of 1:1. The primary endpoint is local relapse-free survival. The secondary endpoints are overall survival, relapse-free survival, proportion of local relapse, proportion of distant relapse, proportion of patients with pathological R0 resection, response rate of preoperative chemoradiotherapy (preoperative chemoradiotherapy arm), pathological complete response rate (preoperative chemoradiotherapy arm), proportion of patients who completed the protocol treatment, incidence of adverse events (adverse reactions), and quality of life after surgery.

Inclusion Criteria:

1. Histopathologically proven adenocarcinoma or adenosquamous carcinoma on the resected specimen of the initial rectal cancer or endoscopic biopsy from the initial rectal cancer.

2. The main tumor location of the initial rectal cancer is upper, middle or lower rectum, or anal canal.

3. Either of the following treatments was performed for the initial rectal cancer, and classified as R0/1 or ER (Endoscopical R)0/1 on pathological diagnosis.

   i) Surgical resection (including local resection, with or without lymph node dissection).

   ii) Endoscopic resection.

4. Patients with distant metastasis during or after treatment for the initial rectal cancer, and radical surgical resection or radical radiotherapy performed more than 168 days before registration is eligible.

5. Recurrent rectal cancer diagnosed by any of the following modalities after treatment for the initial rectal cancer.

   i) The recurrent lesion is pathologically diagnosed. ii) Diagnosed as local recurrence by more than two modalities among contrast-enhanced CT, contrast-enhanced MRI, or positron emission computed tomography (PET).

   iii) Chronological progression of the lesion seen on more than one modality among contrast-enhanced CT, MRI, or PET.

6. The main tumor location is within pelvis as seen on contrast-enhanced CT and MRI if recurrent lesion is multiple, or recurrent lesions spread outside of pelvis continuously.

7. LRRC is diagnosed with no following condition. i) Judged as resectable endoscopically. ii) Depth of invasion within the muscularis propria as seen on contrast-enhanced CT, MRI, or PET in case of recurrence inside the intestine iii) Solitary ovarian metastasis. iv) Recurrence of the common iliac lymph node alone.

8. LRRC is diagnosed as resectable, and all the following conditions must be fulfilled:

   i) No distant metastasis on contrast-enhanced CT (cM0). ii) Estimated circumferential resection margin >0 mm. iii) Leg amputation not required. iv) Preservation of the first sacral nerve possible.

9. No prior surgery for recurrent rectal cancer.

10. No prior pelvic irradiation for any malignancies.

11. A patient who has received systemic chemotherapy for any malignancies and the final dose was administered more than 14 days ago.

12. Age at registration is 20 to 80 years old.

13. Eastern Cooperative Oncology Group (ECOG) performance status is 0 or 1.

14. Measurable lesion is not mandatory.

15. Adequate oral intake.

16. Sufficient organ function. i) Neutrophil count >= 1,500/mm3 ii) Hemoglobin >= 9.0 g/dL iii) Platelet count >= 100,000/mm3 iv) Total Bilirubin =< 2.0 mg/dL v) Aspartate aminotransferase (AST) =< 100 U/L vi) Alanine Aminotransferase (ALT) =< 100 U/L vii) Cr =< 1.5 mg/dL

17. Open surgery or laparoscopic surgery is planned.

18. Written informed consent is obtained.

Exclusion Criteria:

1. Synchronous or metachronous (within 5 years) malignancies except cancer with 5-year relative survival rate of 95% or more such as carcinoma in situ, intramucosal tumor, or early stage cancers.
2. Infections requiring systemic treatment.
3. Body temperature higher than 38 degrees Celsius at registration.
4. Pregnant female, female within 28 days post-parturition, or lactating mother. Men with partners planning conception in the near future.
5. Severe psychological disease.
6. Continuous systemic corticosteroid or immunosuppressant treatment.
7. Uncontrollable diabetes mellitus.
8. Uncontrollable hypertension.
9. Unstable angina pectoris, or history of myocardial infarction within 6 months.
10. Uncontrollable valvular disease, dilated cardiomyopathy, or hypertrophic cardiomyopathy.
11. Positive serum Hepatitis B (HB)s antigen or serum Hepatitis C Virus (HCV) antibody.
12. Positive serum HIV antibody.
13. Interstitial pneumonia, pulmonary fibrosis, or severe emphysema on chest CT.