Accuracy of nodal staging is influenced by sidedness in colon cancer

Adequate lymph node (LN) sampling is critical for accurate nodal staging in colon cancer (CC), particularly for T3N0 disease as current guidelines recommend considering adjuvant chemotherapy when less than 12 LNs are examined. The impact of sidedness on nodal staging accuracy in patients with T3N0 disease has not been previously studied.

Patients with pathologic T3 CC were identified from a prospective multicenter international trial of ultrastaging in CC. The probability of true nodal negativity (TNN) based on the number of LN examined was calculated for right and left CC. These results were then validated in a cohort of patients with similar inclusion criteria selected from the National Cancer Database (NCDB) between 2006 and 2014.

Three hundred and seventy patients met the inclusion criteria in the trial cohort; 48% were LN-negative. Of 153,945 patients in the NCDB, 57% were LN-negative. The probability of TNN when 12 LNs were examined was 68% for right and 64% for left CC in the trial cohort and 77% and 72% in the NCDB. The number of LNs needed to achieve any given probability of TNN was significantly different between right and left CC in both the trial (P<0.001) and the NCDB (P<0.001).

In both a prospective multicenter trial and the NCDB, sidedness influences the number of LNs needed to predict nodal negativity in CC. Current guidelines regarding the minimum number of LNs needed to accurately stage patients with T3N0 CC may need to be re-evaluated by taking into consideration the tumor sidedness.