[702] A Focused Peritumoral Evaluation for Lymph Nodes and a “Second Look” Protocol Improves Nodal Staging of Colon Cancer: A Prospective Study of 102 Colectomies

Mikhail Lisovsky, Shannon Schultz, Arief Suriawinata, Amitabh Srivastava. Dartmouth Hitchcock Medical Center, Lebanon; Brigham & Women's Hospital, Boston

Background: The number of colectomies for colon cancer (CC) in which a minimum of 12-15 lymph nodes (LNs) are examined has increased steadily over time. However, this has not led to a significant increase in the proportion of LN-positive CC. The region within a colectomy with greatest likelihood of finding positive LN is not addressed in the current guidelines. The goal of this study was to evaluate whether LN staging of CC can be improved by a focused LN search in the immediate vicinity of the tumor and a "second look" in cases which are LN-negative on initial examination.
Design: A novel protocol for examining LN in CC was used prospectively. LNs were submitted separately from the primary (PNB) and secondary nodal basin (SNB). PNB and SNB were defined arbitrarily as an area within 5 cm, and >5 cm away from the tumor edge, respectively. A second LN search was performed, by a different prosector, in all cases which were LN-negative on initial examination. 102 consecutive resections were analyzed during an 18 mo period in 2010-2011. 88 consecutive resections over an 18 mo period in 2008-2009 served as the control group for comparison.
Results: 42 CC were LN-positive and 60 LN-negative on initial examination. The number of LNs examined prospectively in cases with one LN search was 23 ± 15.3 (mean ± SD). Cases (initially LN-negative) in which a search was done twice had a LN count of 28 ± 11.9. This was significantly higher than LN counts (19 ± 7.5) in the control group (p<0.0001 and p<0.007, respectively).
The number of LNs in the PNB was 18 ± 8.3, and 22 ± 10.4 for cases with one and two searches, respectively. Positive LNs were present only in the PNB in 39/42 CC and in both the PNB and SNB in the remaining 3 cases.
A second LN search was done in 55/60 initially LN-negative CC. The mean number of additional LNs identified on a second search in the PNB and SNB, was 6.7 and 4.8, respectively. 5 of 55 (9%) initially LN-negative specimens had 1-4 positive LNs on a second search, upstaging CC from N0 to N1 (4 cases) and N2 (1 case). All positive LNs in the second search were in the PNB.
Conclusions: Positive LNs are most often found within the PNB and a focused search of this region yields 12-15 LNs in most resections. A second search in initially LN-negative cases leads to upstaging in 9% of resections. The number of LN examined from the PNB and a "second look" protocol can improve LN staging of CC and can be used as additional quality indicators in pathologic examination of CC.
Category: Gastrointestinal

Monday, March 19, 2012 8:15 AM

Platform Session: Section D, Monday Morning

 

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