Prognostic value of American Joint Committee on Cancer-tumor regression grading combined with ypTN staging in patients with locally advanced rectal cancer

Objective To investigate the prognostic value of American Joint Committee on Cancer-tumor regression grading (AJCC-TRG) combined with ypTN stage in patients with locally advanced rectal cancer (LARC), who were treated with neoadjuvant chemoradiotherapy, and to identify the subgroups with the worst prognosis. Methods A total of 263 patients with LARC, including 176 males and 87 females, with a median age of 55 years, were admitted to Sun Yat-sen University Cancer Center from 2004 to 2012.All the patients received neoadjuvant chemoradiotherapy before surgery and underwent total mesorectal excision at 6 to 8 weeks after radiotherapy. All the surgical specimens were reevaluated according to the AJCC (7th edition)-TRG system and ypTN staging criteria. The prognostic prediction by TRG combined with ypTN was evaluated using survival analysis. The Kaplan-Meier method was used to calculate the rates of overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS). The log-rank test was used for survival comparison and univariate prognostic analysis. Results The median follow-up was 60.1 months. The 5-year rates of OS, DFS, LRFS, and DMFS for all patients were 80.0%, 75.0%, 97.0%, and 81.0%, respectively. There were significant differences in OS, DFS, and DMFS between different ypT/TRG subgroups and different ypN/TRG subgroups (all P<0.05). ypT3-4/TRG 2-3 and ypN1-2/TRG 2-3 subgroups showed the worst prognosis. The 5-year rates of OS, DFS, and DMFS of the two subgroups were 66.9%/56.0%, 52.2%/41.4%, and 60.9%/46.0%, respectively. Conclusions A combination of AJCC-TRG system and ypTN staging can better predict the prognosis of LARC and identify the subgroups with the worst prognosis, which may provide a clinical guidance for postoperative individualized decision on adjuvant therapy for LARC. Key words: Rectal neoplasms/neoadjuvant therapy; Neoadjuvant therapy, radiotherapy; Neoadjuvant therapy, drug; Prognosis