Pathological Predictors of Response to Neoadjuvant Treatment in Rectal Carcinoma

Neoadjuvant chemoradiotherapy has now become a standard treatment for rectal cancer. Recently, attempts have been made to predict the response rate to this treatment to decide whether or not it must be performed. However, tissue factors for predicting the response rate is not cohesively reviewed.

Eighty-three patients with rectal cancer, all under neoadjuvant chemoradiotherapy and subsequent surgery, were examined for tissue factors in the biopsy sample. The tissue factors examined include tumor differentiation grade, lymphovascular invasion, perineural invasion, pathological stage, and lymphocytic infiltration. Lymphocytic infiltration was investigated by immunohistochemistry for CD8 T lymphocyte in biopsy samples.

In this study, tissue factors were found to play a decisive role in predicting response to neoadjuvant treatment. The most important factor was the pathological stage, which has the highest correlation with response to treatment. There is a significant relationship between CD8 lymphocyte infiltration and response to treatment (P value = 0.018). Primary perineural invasion and lymphovascular invasion also have a significant meaningful relationship with response to treatment (P value = 0.021 and P value = 0.036).

In this study, it was determined that the investigated factors have a significant relationship with response to treatment and could be used to predict the response to treatment, and if a low possibility of positive response exists, prevention of the complications of neoadjuvant chemoradiotherapy for the patients could occur.