Number of Lymph Nodes in Primary Nodal Basin and a “Second Look” Protocol as Quality Indicators for Optimal Nodal Staging of Colon Cancer

Abstract

Context.—Evaluation of 12 or more lymph nodes (LNs) is currently used as a quality indicator for adequacy of pathologic examination of colon cancer resections. Objective.—To evaluate the utility of a focused LN search in the immediate vicinity of the tumor and a “second look” protocol in improving LN staging in colon cancer. Design.—Lymph nodes were submitted separately from the primary nodal basin (PNB) and secondary nodal basin (SNB) defined as an area less than 5 cm away and an area greater than 5 cm away from the tumor edge, respectively, in 201 consecutive resections (2010–2013). One hundred sixty-eight consecutive tumors (2006–2009) were used as a control group. A second search was performed in all cases that were N0 after the first search. Results.—In cases that were N0 after the first search, 20.9 ± 10.8 LNs were collected from the PNB, compared to 8.5 ± 9.1 from the SNB. Positive LNs were found in N+ tumors in the PNB in all cases but in only 9% (4 of 46) of SNBs (P < .001). A second search increased node count by an average of 10 additional LNs. In 5 of 114 cases (4.4%), N0 after the first search converted to N+ after a second search that yielded 1 to 4 positive LNs, all of which were in the PNB. Conclusions.—Emphasis on the number of LNs examined from the PNB and a “second look” protocol improve nodal staging.