Re-irradiation Therapy of Locally Recurrent Rectal Cancer With Carbon Ion

Inclusion Criteria: * 1\) pathologically confirmed rectal adenocarcinoma (including mucinous adenocarcinoma and signet-ring cell carcinoma) and LRRC confirmed by biopsy or clinical diagnosis, * 2\) received a radical operation for their primary tumor and regional lymph nodes, * 3\) received chemo-radiation or radiation in pelvic before CIRT, * 4\) received re-irradiation by CIRT after their pelvic radiotherapy. Exclusion Criteria: * 1\) received more than once prior radiotherapy in the same treatment field, * 2\) time to the last radiotherapy was \<1 year, * 3\) space between the lesion to organ at risk (OARs) (bladder or digestive tract) was too close (\<5 mm).