Retrospective study on the prognostic significance of lymph node data post colorectal cancer resection

Abstract

BACKGROUND: Lymph node data regarding the number of lymph nodes resected and studied have been found in previous studies to have prognostic value in patients diagnosed with colorectal cancer (CRC). CRC patients who underwent colorectal resections at Malta’s main hospital, Mater Dei Hospital (MDH), between 2008 and 2011 were selected to assess the prognostic value of such data.

METHODS: The Surgery Department compiled patients who underwent colorectal resections at Mater Dei. Histopathology reports were obtained from MDH’s intranet through iSoft’s iClinical Manager (iCM) and physical files. Microsoft Excel and IBM SPSS statistics were used to compile and analyse the data.

RESULTS: The number of lymph nodes resected showed a mildly significant correlation with overall survival with the Area Under the Receiver Operating Characteristic curve (AUROC) of 0.629 (CI – 95%, p = 0.008) in Stage II CRC patients. 13 lymph nodes were found to be the best cutoff below which there are risks of under-staging of Stage II patients and decreased survival. LNR and number of positive lymph nodes showed more significant correlation with overall survival with AUROC 0.739 (C.I. 95%; p = <0.0001) and 0.726 (C.I. 95%; p = <0.0001) respectively. Both LNR and number of positive lymph nodes correlated significantly with rates of new metastasis with AUROC 0.735 (C.I. = 95%; p = <0.0001) and 0.733 (C.I. = 95%; p = <0.0001), respectively. The best cutoff point for LNR was 8% in both cases.

CONCLUSION: Adequate lymph node exploration and removal are encouraged to avoid under-staging of disease that can potentially occur in Stage II patients with less than 12 lymph nodes resected. Lymph Node Ratio (LNR) provides a better overall picture of lymph node infiltration than N stage and the number of positive lymph nodes.