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Lymph Node Retrieval Following Neoadjuvant Short Course Radiotherapy in Patients with Rectal Cancer

VOLUME 105, ISSUE 1, SUPPLEMENT , E163-E164, SEPTEMBER 01, 2019
DOI:https://doi.org/10.1016/j.ijrobp.2019.06.2138

Purpose/Objective(s): The number and status of lymph nodes (LN) examined is accepted as one of the main prognostic factors in patients with rectal cancer. However, the prognostic role of number of LN evaluation in patients who receive preoperative treatment is unclear. The aim of this study is to define the impact of preoperative short course radiotherapy (SCRT) on the number of both retrieved and positive LN and to evaluate the influence of the number of LN retrieved on survival.

Materials/Methods: From 2011 to 2017, 75 patients who underwent preoperative SCRT followed by mesorectal excision for rectal cancer were evaluated. Patient and tumor characteristics were evaluated. LN numbers were evaluated in two different groups as following: 1- being less or more than 12 as the standard LN number to be retrieved in primary colorectal cancer surgery, 2- being less or more that the median number of LN for the present study. Overall survival(OS) and progression free survival (PFS) were analyzed using Kaplan–Meier for the whole group and according to LN groups. Univariate analysis was performed. Moreover the correlations between mass index (BMI), clinical N stage , SCRT-surgery interval, pathologic N stage, tumor regression grade and LN number, positive LN number, positive LN ratio were evaluated with Pearson’s correlation.

Results: Median follow-up was 34 months. Patient and tumor characteristics are shown in Table 1. There was no significant difference between OS and PFS. However there were negative correlations between RT-surgery interval and total LN number ( r=-0.9), positive LN number (r=-0.1) and positive LN/total LN ratio(r=-0.3). Total LN number and positive LN number were correlated (r=0.4).

Conclusion: In this study, the total number of LN retrieved was not associated with OS and PFS. This may be related to the retrospective nature of the study as well as the limited number of patients included and having a high median LN retrieval number. On the other hand, however there were negative correlations between RT-surgery interval and total LN number, positive LN number and positive LN/total LN ratio. Total LN number and positive LN number were also correlated.