Clarifying the TNM staging of rectal cancer in the context of modern imaging and neo-adjuvant treatment: 'y''u' and 'p' need 'mr' and 'ct'.

Recent developments in cross-sectional imaging, particularly computerized tomography and magnetic resonance imaging have provided increasingly accurate noninvasive preoperative staging, especially for rectal cancer. Image-based TNM staging, by definition a pathological system, has entered both the literature and everyday usage with no universal agreement as to the exact terminology. Clarification of the current terminology and suggestions to reflect recent developments are outlined to facilitate multidisciplinary team decision processes and objective stratification for entry to, and monitoring of, future clinical trials in rectal cancer.