Abstract 2865
Background
Adjuvant chemotherapy (AC) may have benefit in both node negative (N-) and node positive (N+) non-metastatic small bowel adenocarcinoma (SBA). In N- cases, increased number of nodes examined (NNE) has been associated with increased survival. The objective of this analysis was to determine whether N- status is associated with lower NE at time of curative surgery compared to N+ cases, and how many NNE represents adequate sampling.
Methods
SAS 9.4 software and cases of non-metastatic SBA with complete AJCC staging (2004+) from the SEER database were used for this analysis. Age, gender, race, grade, NNE and T stage were compared between N+ and N- cases. Survival analysis using N- cases was performed to determine which nodal cut-offs and variables best predicted survival.
Results
613 cases of non-metastatic SBA (183 N- and 430 N+) diagnosed from 2004 to 2014 were analyzed. T stage and nodal sampling were the only two variables that differed statistically between N- and N+ cases (Table). Using the Log-rank test, a statistical separation in survival curves was identified at a minimum of > =13 NNE (p = 0.0136), a maximum of > =21 NNE (p = 0.0142), and with the greatest statistical separation at > =17 NNE (p = 0.0003). Out of age, gender, race, grade, > =13 NNE, > =17 NNE, > = 21 NNE, and T stage, only age, node cut-off of > =17 (HR 0.47, p=.0032) and T stage remained after stepwise selection of variables for Cox regression modelling. ROC’s for Cox Regression models at 60 months, which included Age, T stage and either > = 13 NNE, > = 17 NNE, or > = 21 NNE were associated with AUC’s of 0.700, 0.717 and 0.667, respectively.Table: 773P
| Node - | Node + | p | |
|---|---|---|---|
| Median Nodes Sampled | 9 | 12 | 0.0008 |
| Proportion of Cases by T Stage | |||
| T1 | 10.9% | 0.7% | <.0001 |
| T2 | 11.5% | 1.6% | <.0001 |
| T3 | 60.7% | 45.4% | 0.0006 |
| T4 | 16.9% | 52.3% | <.0001 |
Conclusions
N- SBAs are associated with decreased nodal sampling compared to N+ SBAs. Low sampling is associated with decreased survival, possibly related to the presence of occult nodal disease. While further work is needed to determine what is considered adequate nodal sampling in N- SBA’s, this analysis suggests that N- cases where less than 17 nodes have been examined have a poorer outcome.
Clinical trial identification
Legal entity responsible for the study
Maclean Thiessen.
Funding
Has not received any funding.
Editorial Acknowledgement
Disclosure
All authors have declared no conflicts of interest.