Compatibility of MRI and Pathological Tumor Regression Grading in Patients with Locally Advanced Rectal Cancer After Undergoing Neoadjuvant Chemoradiotherapy
Alaettin ARSLAN1,Gamze TÜRK2,Saliha KARAGÖZ EREN3,Ebru AKAY4,Nail ÖZHAN5,İpek Pınar ARAL6
1Department of Radiation Oncology, Kayseri City Hospital, Kayseri-Turkey
2Department of Radiology, Kayseri City Hospital, Kayseri-Turkey
3Department of Genaral Surgery, Kayseri City Hospital, Kayseri-Turkey
4Department of Pathology, Kayseri City Hospital, Kayseri-Turkey
5Department of Medical Oncology, Kayseri City Hospital, Kayseri-Turkey
6Department of Radiation Oncology, Nevsehir State Hospital, Nevsehir-Turkey
DOI : 10.5505/tjo.2021.2873 OBJECTIVE
The compatibility between magnetic resonance imaging tumor regression grade (mrTRG) and pathological tumor regression grade (pTRG) was examined in patients with locally advanced rectal cancer (LARC) who underwent neoadjuvant chemoradiotherapy (nCRT). The primary endpoint of the study was to evaluate the relationship between mrTRG and pTRG after nCRT. The secondary endpoint of the study was to evaluate the variables that affect mrTRG and pTRG.

Forty-one patients with LARC treated with nCRT were analyzed. Magnetic resonance imaging (MRI) performed after nCRT was compared with MRI taken before nCRT. Changes in T and N stages and extramural vascular invasion positivity were investigated. TRG was divided into five groups in terms of pathological and MRI. The Dworak pTRG system was used for compatibility testing. MRI sensitivity and specificity were evaluated by comparing MRI-based response assessment with pathological assessment after nCRT.

Median patient age was 61 years (range, 26?79 years), and 18 (43.9%) were female. The relationship between mrTRG and pTRG was evaluated with the Cohen kappa coefficient. Significant compatibility was observed between pTRG and mrTRG (p=0.002), but the compatibility was low (kappa compatibility, 0.319). The sensitivity of mrTRG was 90% (18/20); specificity was 14.3% (3/21); positive predictive value was 85.7% (18/21); and negative predictive value was 90% (18/20). While pTRG was negatively affected by advanced age (p=0.037), mrTRG was adversely affected by advanced post-nCRT N stage (p=0.048).

As age increased, pTRG was negatively affected; as the post-nCRT N stage increased, mrTRG was negatively affected. There was compatibility between mrTRG and pTRG, as expected, but this compatibility was found to be low. Keywords : MRI; neoadjuvant chemoradiotherapy; rectal cancer; tumor regression grade