ypTNM category combined with AJCC tumor regression grade for screening patients with the worst prognosis after neoadjuvant chemoradiation therapy for locally advanced rectal cancer.

Background: The purpose of this study was to investigate the value of the postsurgical pathological T and N (ypTN) category combined with the American Joint Committee on Cancer-tumor regression grade (AJCC-TRG) in evaluating the prognosis of neoadjuvant chemoradiation therapy (NeoCRT) for locally advanced rectal cancer (LARC) to screen for a subgroup of patients with the worst prognosis.

Patients And Methods: In total, 265 patients with LARC were enrolled in the trial. All patients received NeoCRT. Total mesorectal excision was performed 6-8 weeks after the completion of radiotherapy. The surgical specimens were re-evaluated based on the AJCC-TRG (seventh edition) and the AJCC-tumor-node-metastasis (TNM; seventh edition) systems. We followed up these patients and calculated their overall survival (OS), disease-free survival (DFS), local recurrence-free survival (RFS), and distant metastasis (DM)-free survival (MFS) rates through the Kaplan-Meier analysis. The logrank test was further applied to evaluate the predictive value of the ypTN stage combined with AJCC-TRG for several survival indexes.

Results: The median follow-up period was 65.1 months. The 5-year OS, DFS, RFS, and MFS rates were 79.4%, 68.8%, 94.4%, and 76.5%, respectively. There were significant differences in OS, DFS, and MFS rates among different ypT+AJCC-TRG and ypN+AJCC-TRG subgroups. The 5-year OS, DFS, and MFS rates for ypT3-4+TRG 1 and ypT3-4+TRG2-3 subgroups were 73.9% vs 65.3%, 61.2% vs 52.9%, and 65.0% vs 61.5%, respectively. The 5-year OS, DFS, and MFS rates for ypN1-2+TRG 0-1 and ypN1-2+TRG2-3 subgroups were 64.8% vs 54.1%, 44.9% vs 41.7%, and 61.4% vs 46.3%, respectively.

Conclusion: The ypTNM category combined with the AJCC-TRG can more accurately evaluate the prognosis of patients with LARC and identify the subgroup of patients with the worst prognosis and high risk of developing DM, thereby demonstrating clinical significance in guiding individualized postoperative adjuvant therapy and follow-up for LARC.