Evaluation of histological regression grading systems in the neoadjuvant therapy of rectal cancer

Purpose Neoadjuvant treatment options have been developed to improve survival of patients with locally advanced rectal cancer. As only patients with a major histopatholocial response benefit from this preoperative therapy, several tumor regression grading systems have been developed. However, currently no accepted comprehensive grading system for clinical use is available. Therefore, we studied the impact of four histological regression grading systems in the neoadjuvant therapy of rectal cancer. Methods In this retrospective study, 85 patients with locally advanced rectal cancer were included. All patients received a neoadjuvant radiochemotherapy followed by surgical resection. The histological regression grading was evaluated using four classification systems: (1) grading system by the Japanese society of colorectal cancer, (2) grading system by Junker-Müller, (3) grading system by Dworak, (4) Cologne grading system. The four classification systems were analyzed for their prognostic impact. Results The following significant correlations were detected between the four classification systems and the ypTNM categories: (1) patients with a ypT3/4 category had significantly more often a worse histopathologic response in all four grading systems (p = 0.001); (2) a ypN0 category was significantly correlated with good histopathologic response only in the Cologne grading system; (3) in the Junker-Müller and Dworak grading systems, a ypM0 category was significantly correlated with a good histopathologic response (p = 0.046; p = 0.03). However, none of the used classification systems had a prognostic impact on survival. Conclusions Currently, none of the analyzed histological regression grading systems is effective for clinical use.