Correlation between Lymph Node Regression Grading and Tumor Regression Grading after Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer

Abstract

This study aimed to determine the relationship between tumor regression grading (TRG) and lymph node regression grading (LRG) after neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer (LARC). The study was a retrospective analysis of the clinical data of LARC patients who underwent preoperative nCRT at one institution. A total of 101 rectal cancer patients who received nCRT and underwent total rectal mesenteric excision (TME) were included. Pathologists independently assessed the pathological response of the primary tumor and lymph nodes (LN) to nCRT using TRG and LRG, respectively. The highest LRG score for each patient was defined as LRGmax, and LRGsum was the overall tumor burden of all LNs in the specimen. The study included 101 LARC patients who underwent nCRT and TME. The patient population consisted of 65 males and 36 females with an average age of 54.86 years (range 20-81 years), of which 68 were aged 60 years or younger and 33 were older than 60. The radiotherapy treatment plan consisted of 1.8-2Gy per dose, administered 5 times per week for a total dose of 45-50.4Gy, along with oral capecitabine chemotherapy (825 mg/m2, bid) on the day of radiation therapy. The chemotherapy treatment plan included XELOX, mFOLFOX6, and FOLFOX4. The cTNM stage of the tumor before surgery was cT2 in 2 cases, cT3 in 63 cases, and cT4 in 36 cases. Eight cases were cN0 and 93 were cN+. After surgery, the ypTNM stage was T0 in 19 cases, T1 in 4 cases, T2 in 27 cases, T3 in 45 cases, and T4 in 6 cases. The N stage was N0 in 76 cases, N1 in 20 cases, and N2 in 5 cases. TRG was 0 in 17 cases (16.8%), 1 in 15 cases (14.9%), 2 in 61 cases (60.4%), and 3 in 8 cases (7.9%). LRGmax scores were 0 in 66 cases (65.3%), 1 in 17 cases (16.8%), 2 in 5 cases (5.0%), 3 in 3 cases (3.0%), 4 in 5 cases (5.0%), and 5 in 5 cases (5.0%). LRGsum scores were ≤3 in 85 cases (84.2%), 4-9 in 11 cases (10.9%), and ≥10 in 5 cases (5.0%). Correlation analysis showed that LRGmax was significantly correlated with TRG, ypT, and ypN (P = 0.038, P = 0.015, P < 0.01), with correlation coefficients of 0.184, 0.212, and 0.626, respectively. There was no significant correlation between LRGmax and cT and cN+. Similarly, LRGsum was significantly correlated with TRG, ypT, and ypN (P = 0.022, P = 0.002, P < 0.01) with correlation coefficients of 0.212, 0.276, and 0.707, respectively. There was no significant correlation between LRGsum and cT and cN. The results of our study indicate a significant correlation between LRG and TRG (P = 0.022). Additionally, LRG was found to be positively correlated with the ypT and ypN stages of the primary tumor and lymph nodes post-surgery, with correlation coefficients of 0.276 and 0.707, respectively (P = 0.002 and P<0.01). No significant correlations were observed between LRG and cT and cN+ stages. Our findings demonstrate a significant association between LRG and TRG, as well as a positive correlation between LRG and the ypT and ypN stages of the primary tumor and lymph nodes following surgery.