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

Abstract

-Evaluation of 12 or more lymph nodes (LNs) is currently used as a quality indicator for adequacy of pathologic examination of colon cancer resections. -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. -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. -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. -Emphasis on the number of LNs examined from the PNB and a "second look" protocol improve nodal staging.