Increased lymph node yield in colorectal cancer is not necessarily associated with a greater number of lymph node positive cancers.

Aisling O'Shea,Craig N Parnaby,Malcolm A Loudon,Leslie M Samuel,Omar Aly,Graeme I Murray

doi:10.1371/journal.pone.0104991

Aisling O'Shea, Craig N Parnaby + Show 4 more

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https://doi.org/10.1371/journal.pone.0104991

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Abstract

The presence of lymph node metastasis is a key prognostic factor in colorectal cancer and lymph node yield is an important parameter in assessing the quality of histopathology reporting of colorectal cancer excision specimens. This study assesses the trend in lymph node evaluation over time in a single institution and the relationship with the identification of lymph node positive tumours. It compares the lymph node yield of a contemporary dataset compiled from the histopathology reports of 2178 patients who underwent surgery for primary colorectal cancer between 2005 and 2012 with that of a historic dataset compiled from the histopathology reports of 1038 patients who underwent surgery for colorectal cancer at 5 yearly intervals from 1975 to 2000. The mean lymph node yield was 14.91 in 2005 rising to 21.38 in 2012. In 2012 92.9% of all cases had at least 12 lymph nodes examined. Comparison of the mean lymph node yield and proportion of Dukes C cases shows a significant increase (Pearson correlation = 0.927, p = 0.001) in lymph node yield while there is no corresponding significant trend in the proportion of Dukes C cases (Pearson correlation = −0.138, p = 0.745). This study shows that there is increasing yield of lymph nodes from colorectal cancer excision specimens. However, this is not necessarily associated with an increase number of lymph node positive cancers. Further risk stratifying of colorectal cancer requires consideration of other pathological parameters especially the presence of extramural venous invasion and relevant biomarkers.

Highlights

Detection of metastasis in tumour-associated lymph nodes has a highly significant effect on prognosis in patients with colorectal cancer
The information recorded in this database includes age, gender, year of operation, administration of neoadjuvant therapy, whether the tumour was screen detected, tumour site, tumour differentiation, tumour (T) stage, extramural venous invasion (EMVI), total number of lymph nodes examined, number of lymph nodes involved by metastatic tumour, nodal (N) stage and Dukes stage
Information for all parameters was complete for the contemporary database where as significant proportion of pathology reports in the historic dataset had no information documented on gender (12.8%), age (10.4%), number of lymph nodes retrieved (66%) and number of lymph nodes involved by metastatic tumour (66.6%)

Summary

Introduction

Detection of metastasis in tumour-associated lymph nodes has a highly significant effect on prognosis in patients with colorectal cancer. All patients with one or more lymph nodes displaying metastasis are upstaged to Dukes C/stage 3 disease. This has important therapeutic consequences for a patient, as all these patients are considered for treatment with adjuvant chemotherapy. [1,2,3,4] according to current guidelines inadequate detection of positive lymph nodes can lead to under treatment of lymph node positive colorectal cancer. It is generally considered and accepted that examining more lymph nodes in a colorectal cancer excision specimen increases the likelihood of identifying involved lymph nodes and upstaging the cancer.

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