There is a lack of international consensus on the choice of preoperative treatment for patients with rectal cancer. Existing guidelines decide whether to administer preoperative therapy to patients with rectal cancer mainly based on the TNM system developed by AJCC/UICC, however, radiographic TNM staging is unsatisfactory in predicting the prognosis of patients with rectal cancer, due to inflammatory and fibrotic responses TNM re-staging is less accurate than pre-treatment. Studies have shown that high-resolution magnetic resonance imaging(MRI) accurately predicted pathologic findings such as CRM involvement, EMVI and TD and patients with MRI-detected CRM involvement, EMVI and TD are at risk for local and distant recurrence as well as poor overall survival. This retrospective study is designed to was to evaluate whether risk criteria based on MRI features can be used as a basis for neoadjuvant treatment decisions and more accurately indicate the response to the treatment and predict prognosis after neoadjuvant treatment than radiographic TNM staging. Patients with MRI-detected circumferential resection margin (CRM) involvement, extramural venous invasion (EMVI), or tumor deposits (TD) were defined as MRI high-risk.
This study investigates whether risk criteria based on MRI features could identify a cohort of patients with a good prognosis among those recommended for preoperative treatment by NCCN guidelines to avoid preoperative treatment with the likely good survival outcomes by primary surgery and more accurately indicate the response to the treatment and predict prognosis after neoadjuvant treatmen than radiographic TNM staging in the patients who received neoadjuvant therapy.