[Pathological evaluation after preoperative neoadjuvant treatment in rectal cancer]

Preoperative neoadjuvant therapy of rectal cancer has been widely promoted, and postoperative standardized pathological assessment has gradually attracted widespread attention. Accurate pathological examination plays an indicating role in the diagnosis and treatment of rectal cancer, which can not only evaluate the effects of neoadjuvant chemoradiation and surgical resection, but also guide postoperative adjuvant therapy and assess the prognosis. Tumor regression grade (TRG) and TNM staging are the bases of routine pathological diagnosis of rectal cancer, and they are closely related to patient survival and prognosis. At present, TRG evaluation methods for neoadjuvant chemoradiation include NCCN, AJCC, Becke, Mandard, Dowrak/Rodel, MSKCC, and RCRG. However, there is still no universally accepted best standard. The commonly used classifications in practice are AJCC and NCCN TRG grading standards. The prerequisite for accurate TRG classification is a detailed and standardized pathological assessment, which includes both gross assessment of the specimen and microscopic examination. How to evaluate the therapeutic response to lymph node metastasis after neoadjuvant therapy and improve the assessment consistency among pathologists are the two major issues that remain to be resolved.