Relationship Between Neoadjuvant Chemoradiotherapy Response and Mesorectum Volume in Rectum Cancer

Aim:To investigate the relationship between changes in mesorectum volume (MRV) following neoadjuvant chemoradiotherapy (nCRT) and pathological and clinical response in patients with locally advanced rectum cancer (LARC).Methods: The study included 39 patients who received nCRT for LARC and underwent surgery between January 2016 and April 2019.The MRV was measured on magnetic resonance imaging (MRI) before and after nCRT.Patients were separated into two groups based on an increase or decrease in MRV following nCRT.The relationships were examined between the 2 groups and the pathological T and N statuses, pre-and post-nCRT T and N statuses, and the degree of MRI regression and pathological regression.Results: A retrospective analysis was performed on 39 patients, consisting of 19 males and 20 females, with a mean age of 59.3 years (range, 27-80 years).The mean MRV was 116.8 mm 3 (range, 49.9-253.9)before and 115.5 mm 3 (50.9-196.7)after nCRT.There was an increase in MRV in 21 patients and a decrease in 18 patients.In the MRI evaluation, there was no response to nCRT in 4 patients, and in the pathological evaluation, a response could not be determined in 9 patients.Conclusion: Because this study is one of the first in the literature to investigate the relationship between changes in MRV and response to nCRT, further studies are needed to reach more meaningful results.