Evaluating the Impact of Lymph Node Resampling on Colorectal Cancer Nodal Stage

AIMS Nodal staging in colorectal cancer (CRC) informs prognosis and guides adjuvant treatment decisions. A standard minimum of 12 lymph nodes is widely used, with additional sampling performed as required. However, there is little data on how lymph node resampling in this context has an impact on nodal stage. The aim of this study was to evaluate the effectiveness of resampling in detecting metastases and tumour deposits, and the impact on stage. METHODS AND RESULTS A retrospective cohort analysis was performed on CRC resections that underwent resampling due to an initial yield of <12, from 2008-2018. Data relating to the patient demographics, specimen, malignancy, and prosection were collected. Slides were reviewed to quantify nodal metastases and tumour deposits before and after resampling. Among ≥pN1 cases, logistic regression analysis was performed to evaluate factors that predicted finding additional metastases and tumour deposits. The cohort comprised 395 cases, of which resampling identified nodal metastases and/or tumour deposits in 30 (7.6%) cases; nodal upstaging occurred in 20 (5.1%) cases; 8 (2.0%) changed from pN0 to ≥pN1. No factors predicted resampling positive lymph nodes or tumour deposits, and pN upstaging occurred across a variety of cases. A subgroup analysis was performed to assess the impact of resampling on high-risk features in stage II cases (n=117). There were 33 (8.5%) patients who no longer had any high-risk features after resampling. CONCLUSIONS Lymph node resampling has an impact on nodal staging and possible treatment decisions in a considerable proportion of patients and is recommended in all cases with <12 lymph nodes.