The Current Status of Nodal Staging in Rectal Cancer

To review current practice in MRI-based nodal staging in rectal cancer and assess the associated evidence. Nodal staging is less accurate than other MRI-detected prognostic markers such as circumferential resection margin status, extramural venous invasion and T stage. Previous research has focused on matching MRI and pathology findings but crucially N stage has never been shown to have prognostic importance on MRI. Recent pathological evidence suggests that tumour deposits may be more important than nodal status and these can be clearly distinguished from nodal metastases on MRI. Nodal staging on MRI is prognostically inaccurate. MRI staging should move away from TNM to focus on those radiological markers which can be proved to have prognostic accuracy. Tumour deposits should be reported separately to lymph node metastases on both histopathology and imaging. Research is underway confirming their prognostic importance on MRI.