College of American Pathologists Tumor Regression Grading System for Long-Term Outcome in Patients with Locally Advanced Rectal Cancer
Background: The National Comprehensive Cancer Network's Rectal Cancer Guideline Panel recommends American Joint Committee of Cancer and College of American Pathologists (AJCC/CAP) tumor regression grading (TRG) system to evaluate pathologic response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer (LARC). Yet, the clinical significance of the AJCC/CAP TRG system has not been fully defined. Materials and Methods: This was a multicenter, retrospectively recruited, and prospectively maintained cohort study. Patients with LARC from one institution formed the discovery set, and cases from external independent institutions formed a validation set to verify the findings from discovery set. Overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were assessed by Kaplan-Meier analysis, log-rank test, and Cox regression model. Results: The discovery set (940 cases) found, and the validation set (2,156 cases) further confirmed, that inferior AJCC/CAP TRG categories were closely /ccorrelated with unfavorable survival (OS, DFS, LRFS, and DMFS) and higher risk of disease progression (death, accumulative relapse, local recurrence, and distant metastasis) (all p <.05). Significantly, pairwise comparison revealed that any two of four TRG categories had the distinguished survival and risk of disease progression. After propensity score matching, AJCC/CAP TRG0 category (pathological complete response) patients treated with or without adjuvant chemotherapy displayed similar survival of OS, DFS, LRFS, and DMFS (all p >.05). For AJCC/CAP TRG1–3 cases, adjuvant chemotherapy treatment significantly improved 3-year OS (90.2% vs. 84.6%, p <.001). Multivariate analysis demonstrated the AJCC/CAP TRG system was an independent prognostic surrogate. Conclusion: AJCC/CAP TRG system, an accurate prognostic surrogate, appears ideal for further strategizing adjuvant chemotherapy for LARC. Implications for Practice: The National Comprehensive Cancer Network recommends the American Joint Committee of Cancer and College of American Pathologists (AJCC/CAP) tumor regression grading (TRG) four-category system to evaluate the pathologic response to neoadjuvant treatment for patients with locally advanced rectal cancer; however, the clinical significance of the AJCC/CAP TRG system has not yet been clearly addressed. This study found, for the first time, that any two of four AJCC/CAP TRG categories had the distinguished long-term survival outcome. Importantly, adjuvant chemotherapy may improve the 3-year overall survival for AJCC/CAP TRG1–3 category patients but not for AJCC/CAP TRG0 category patients. Thus, AJCC/CAP TRG system, an accurate surrogate of long-term survival outcome, is useful in guiding adjuvant chemotherapy management for rectal cancer.
Oxford University Press
Chen, Hai Yang; Feng, Li Li; Li, Ming; Ju, Huai Qiang; Ding, Yi; Lan, Mei; Song, Shu Mei; Han, Wei Dong; Yu, Li; Wei, Ming Biao; Pang, Xiao Lin; He, Fang; Liu, Shuai; Zheng, Jian; Ma, Yan; Lin, Chu Yang; Lan, Ping; Huang, Mei Jin; Zou, Yi Feng; Yang, Zu Li; Wang, Ting; Lang, Jin-Yi; Orangio, Guy R.; Plylin, Vitaliy; Ajani, Jaffer A.; Wang, Wei-Hu; and Wan, Xiang-Bo, "College of American Pathologists Tumor Regression Grading System for Long-Term Outcome in Patients with Locally Advanced Rectal Cancer" (2021). School of Medicine Faculty Publications. 378.