Effect of Lymph Node Count on Pathological Stage III Rectal Cancer with Preoperative Radiotherapy.

Qingguo Li,Lu Gan,Xinxiang Li,Sanjun Cai,Lei Liang,Guoxiang Cai

doi:10.1038/srep16990

Abstract

Lymph node (LN) status after surgery for rectal cancer is affected by preoperative radiotherapy. The purpose of this study was to perform a population-based evaluation of the impact of pathologic LN status after neoadjuvant radiotherapy on survival. A total of 1,650 patients receiving neoadjuvant chemotherapy in Surveillance, Epidemiology, and End Results Program (SEER)-registered ypIII stage rectal cancer was analyzed. We identified the optimal cutoff for retrieved LNs as 10 (χ2 = 14.006, P < 0.001), which was validated as an independent prognosis factors in a Cox regression model. Further analysis showed that the LN count was only a prognosis factor with the number from 8 to 16(except for 13).After the number 16, the 5-year survival rate decreased gradually. Collectively, our results confirmed that the number of LNs in yp III stage rectal patients was a prognosis factor only with the numbers from 8 to 16(except for 13). Using the total mesorectal excision technique with an adequate pathologic examination, a large number of LNs retrieved (≥17) might indicate worse tumor response grade and poorer survival.

Highlights

Lymph node (LN) status after surgery for rectal cancer is affected by preoperative radiotherapy
One possible method of identifying a reasonable cutoff value that allows the reliable staging of rectal cancer with LNs metastases treated with preop-RT is to analyze patient survival in a large series of patients diagnosed as ypN(+ )
The total number of LNs retrieved is fundamental in most pathological staging systems for colorectal cancer, including the American Joint Committee on Cancer (AJCC), modified Dukes and Astler and Coller

Summary

Introduction

Lymph node (LN) status after surgery for rectal cancer is affected by preoperative radiotherapy. According to the guidelines for colorectal cancer from the National Comprehensive Cancer Network (NCCN), a minimum of twelve lymph nodes (LNs) must be retrieved and examined for accurate staging and the number of metastatic LNs was validated as an independent prognostic factors[3,4,5]. One possible method of identifying a reasonable cutoff value that allows the reliable staging of rectal cancer with LNs metastases treated with preop-RT is to analyze patient survival in a large series of patients diagnosed as ypN(+ ). The purpose of this study was to assess the impact of the number of LNs examined on survival of rectal cancer patients treated with preop-RT at ypN(+ ) stage and to determine the optimal number of LNs that should be examined

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Conclusion