Is the pathological regression level of metastatic lymph nodes associated with oncologic outcomes following preoperative chemoradiotherapy in rectal cancer?
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Jung Pil Choi4,*, Sung Joo Kim2,*, In Ja Park1, Seung Mo Hong2, Jong Lyul Lee1, Yong Sik Yoon1, Chan Wook Kim1, Seok-Byung Lim1, Jung Bok Lee3, Chang Sik Yu1, Jin Cheon Kim1
1Departments of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
2Departments of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
3Departments of Clinical Epidemiology and Biostatistics, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
4Department of Surgery, Dong Kang Medical Center, Ulsan, Korea
*These authors have contributed equally to this work
In Ja Park, email: email@example.com
Keywords: rectal cancer, preoperative chemoradiotherapy, lymph node regression, primary tumor regression, oncologic outcome
Received: August 25, 2016 Accepted: December 13, 2016 Published: January 02, 2017
Purpose: The oncologic impact of the lymph node (LN) regression level after preoperative chemoradiotherapy (PCRT) has not been thoroughly evaluated. Hence, this study aimed to examine whether the regression level of metastatic LNs following PCRT is associated with oncologic outcomes in rectal cancer.
Results: The optimal number of cut points for LRG sum was determined to be three. The three LRG groups demonstrated different distributions according to the ypT and ypN stages (p < 0.001 for both). However, the distribution of the LRG groups was not associated with the TRG of the primary tumor (p = 0.527). The RFS significantly differed according to the LRG groups (p = 0.001). Moreover, the differences in RFS remained when the LRG groups were analyzed within each separate ypN stage. The LRG group was confirmed as a factor associated with RFS in the multivariate analysis (p=0.018), while the ypN stage was not (p=0.4).
Patients and Methods: We analyzed the outcomes of 142 rectal cancer patients diagnosed with ypN1 disease after PCRT followed by radical resection. The pathological responses of the primary tumor and LNs to PCRT were evaluated using the tumor regression grade (TRG) and LN regression grade (LRG), respectively. The impact of LRG on recurrence-free survival (RFS) was analyzed. The K-adaptive partitioning for survival data method was applied to determine the optimal number of cut points for the LRG-sum and the optimal number of subgroups.
Conclusion: The LRG as an indicator of response to PCRT should be considered as a prognostic determinant in rectal cancer patients. Future large-scale prospective studies are needed to confirm this finding.
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