Investigating the association between radiological images and the pathology of rectal cancer treated with neoadjuvant chemotherapy

In patients with rectal cancer treated with neoadjuvant chemotherapy (NAC), differences are often observed between high and low radiological image reduction effects. It may be suggested that high radiological image reduction indicates a beneficial response to chemotherapy. However, the pathological investigation of the differences between high and low radiological cancer volume reduction cases remains limited. In the current study, a total of 50 patients with rectal cancer, treated with NAC, were examined. The approximate pathological primary cancer area and the radiological cancer volume reduction ratio were measured using CT and/or MRI imaging and the donut-shaped measurement method. Immunostaining of cytokeratin AE1/AE3 was performed to quantitatively measure the cancer cell mass in the largest section of rectal cancer. Cytokeratin AE1/AE3-stained area (P=0.04), mitosis (P=0.0027) and radiological donut-shaped images after NAC (P=0.010) were lower in the high radiological cancer volume reduction ratio group compared with the low radiological cancer volume reduction ratio group. These findings indicate that the radiological images had some ability to determine the treatment effect and clinicopathological characteristics of patients with rectal cancer treated with NAC.