Prognostic Analysis of Patients with TRG1 after Neoadjuvant Chemoradiotherapy in Rectal Cancer: Tumor Regression Pattern Will Affect Survival

Abstract

<h3>Purpose/Objective(s)</h3> Tumor regression grade (TRG) is an evaluation method to reflect tumor response to neoadjuvant chemoradiotherapy (NCRT) in patients with rectal cancer. Tumor shrinks dramatically in the case of TRG1 and shows high sensitivity to NCRT. However, the prognosis of patients who had TRG1 was different from each other. Additionally, there may be two different ways of tumor response to NCRT: shrinkage or fragmentation, and whether the patterns of tumor regression would affect prognosis is still not clear. The purpose of this study is to assess which factors would affect the survival of TRG1 patients. <h3>Materials/Methods</h3> This is a retrospectively analysis of patients with locally advanced rectal cancer (LARC) and received NCRT at our institution. TRG scores were evaluated according to the guideline of National Comprehensive Cancer Network (NCCN). We analyzed several clinicopathological factors and their relationship with survival outcome including overall survival (OS) and disease-free survival (DFS). <h3>Results</h3> A total of 73 patients were enrolled in this study including 46 males (63.0%) and 27 females (37.0%). The median age was 59 years (range,26-84). Among them, 33 showed tumor shrinkage, while 40 (54.8%) showed tumor fragmentation. Fifteen (20.5%) patients were diagnosed as stage I, twenty-two (30.1%) as stage II, and thirty-six patient (49.3%) as stage III after surgery. There were 19.2%, 47.9%, and 32.9% of patients with high, intermediate, and low NAR score respectively. In univariate analysis, tumor regression pattern (<i>p</i>=0.004), pathologic TNM stage (<i>p</i>=0.026) and neoadjuvant rectal cancer (NAR) score (<i>p</i>=0.041) was associated with DFS. Only tumor regression pattern showed prognostic significance for DFS in multivariate analysis (HR=10.659, 95%CI 1.384-82.118, <i>p</i>=0.023). All deaths were observed in fragmentation group. <h3>Conclusion</h3> Tumor regression pattern was an independent factor affecting DFS in LARC patients with TRG1. Patients with tumor shrinkage response had more favorable prognosis compared to fragmented response.