MRI Tumor Regression Grade Combined with T2-Weighted Volumetry May Predict Histopathological Response in Locally Advanced Rectal Cancer following Neoadjuvant Chemoradiotherapy-A New Scoring System Proposal

Aleksandra Jankovic; Jelena Djokic Kovac; Marko Dakovic; Milica Mitrovic; Dusan Saponjski; Ognjen Milicevic; Aleksandra Djuric-Stefanovic; Goran Barisic

doi:10.3390/diagnostics13203226

MRI Tumor Regression Grade Combined with T2-Weighted Volumetry May Predict Histopathological Response in Locally Advanced Rectal Cancer following Neoadjuvant Chemoradiotherapy-A New Scoring System Proposal

Diagnostics (Basel). 2023 Oct 17;13(20):3226. doi: 10.3390/diagnostics13203226.

Authors

Aleksandra Jankovic^{1

2}, Jelena Djokic Kovac^{1

2}, Marko Dakovic³, Milica Mitrovic^{1

2}, Dusan Saponjski^{1

2}, Ognjen Milicevic², Aleksandra Djuric-Stefanovic^{1

2}, Goran Barisic^{2

4}

Affiliations

¹ Department for Digestive Radiology, Center for Radiology, University Clinical Center of Serbia, Pasterova No. 2, 11000 Belgrade, Serbia.
² Faculty of Medicine, University of Belgrade, Dr. Subotica No. 8, 11000 Belgrade, Serbia.
³ Faculty of Physical Chemistry, University of Belgrade, 11000 Belgrade, Serbia.
⁴ Clinic for Digestive Surgery-First Surgical Clinic, University Clinical Center of Serbia, Koste Todorovica No. 6, 11000 Belgrade, Serbia.

Abstract

Modern studies focus on the discovery of innovative methods to improve the value of post-treatment magnetic resonance imaging (MRI) in the prediction of pathological responses to preoperative neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC). The aim of this study was to assess the potential benefits of combining magnetic resonance tumor regression grade (mrTRG) with T2-weighted volumetry in the prediction of pathological responses to nCRT in LARC. This was a cohort study conducted on patients with histopathologically confirmed LARC in a period from 2020 to 2022. After histopathological verification, all patients underwent initial MRI studies, while the follow-up MRI was performed after nCRT. Tumor characteristics, MRI estimated tumor regression grade (mrTRG) and tumor volumetry were evaluated both initially and at follow-up. All patients were classified into responders and non-responders according to pathological tumor regression grade (pTRG) and mrTRG. A total of 71 patients, mostly male (66.2%) were included in the study. The median tumor volume reduction rate was significantly higher in nCRT-responders compared to non-responders (79.9% vs. 63.3%) (p = 0.003). Based on ROC analysis, optimal cut-off value for tumor volume reduction rate was determined with an area under the curve (AUC) value of 0.724 (p = 0.003). Using the tumor volume reduction rate ≥75% with the addition of response to nCRT according to mrTRG, a new scoring system for prediction of pTRG to preoperative nCRT in LARC was developed. Diagnostic performance of prediction score was tested and the sensitivity, PPV, specificity, and NPV were 81.8%, 56.3%, 71.4%, and 89.7%, respectively. The combination of mrTRG and T2-weighted volumetry increases the MRI-based prediction of pTRG to preoperative nCRT in LARC. The proposed scoring system could aid in distinguishing responders to nCRT, as these patients could benefit from organ-preserving treatment and a "watch and wait" strategy.

Keywords: magnetic resonance imaging; magnetic resonance volumetry; non-responders; rectal cancer; responders.

Grants and funding

This research received no external funding.