Colorectal Lymph Node Examination: How Extensive Should It Be and Why Is 12 the Magic Number? A VAMC Experience
H Al-Ghawi, HX Bui, JP Reynolds, G Luo, P Horn, S Samaan, M Molloy. VA Medical Center, Cincinnati, OH; University of Cincinnati
Background: Twelve lymph nodes (LN) is a current benchmark in LN retrieval in colorectal resections according to the National Quality Forum. Data shows that more extensive lymphadenectomy improves overall survival (OS). These are multi institutional studies which have many variables such as length of colonic fat resected by many surgeons, and gross examination by many path labs. By using one surgeon's case log and one pathology group, we have the opportunity to reduce these variables. Our aim is to determine the impact of extensive LN search on OS, and the impact of 12 LN as a QA standard.
Design: We reviewed 157 patients from one surgeon's case log between 1994-2007. Within the 12 years, one surgeon applied strict guidelines to remove approximately the same distribution of pericolonic fat and the lab followed a 2 step approach to LN dissection. Step 1 is careful search for grossly identifiable LN, and step 2 is overnight immersion in Carnoy's solution to find smaller LN. We used Statview, Kaplan Meier Analysis and SAS Institute software to analyze the following variables: 1) The total number of LN identified and its impact on AJCC stage and OS 2) The OS and its association with finding of >12 LN 3) The impact of number of positive LN on OS.
Results: Of 157 cases, the mean number of identified LN for all resections was 14.75 1) The total number of LN identified did not correlate with AJCC stage (p=0.42) Mean number of LN per stage: I=13.4 (N=41); II=16.3 (N=56); III=14.3 (N=38); IV 14.2 (N=22). Regardless of stage, total number of LN identified was not statistically significant in predicting OS (p=0.24) 2) Regardless of tumor stage, no statistically significant impact on OS was found if <12 or >12 total LN were identified (p=0.06) 3) Regardless of tumor stage, higher number of positive LN was associated with lower OS (Survival decreases by 0.15 month per each positive node, p= 0.001).
Conclusions: 1) Total number of LN identified does not impact AJCC stage or OS 2) Higher number of positive LN alone is associated with worse OS In our experience, the two step LN isolation is an effective way to exceed the National Quality Forum requirement of 12 LN. However, after following our own guidelines for over ten years, our findings suggest that the second step of using carcinogens like Carnoy's solution may not be needed. Twelve lymph nodes may not be a magic number for QA and should be reconsidered.
Tuesday, March 10, 2009 8:30 AM
Platform Session: Section C, Tuesday Morning