Impact of lymph node evaluation on survival for small bowel adenocaricnoma: Analysis of the Surveillance, Epidemiology and End Results (SEER) database

Abstract

4596 Background: Small bowel adenocarcinoma is a rare malignancy and is often associated with poor outcome. The impact that the number of positive and negative lymph nodes (LN) have upon survival following curative resection has not been studied. Methods: Patients aged 18–90 with adenocarcinoma of the small intestine diagnosed between 1988 and 2005 were identified from SEER data (ver. 2008). Disease-specific survival (DSS) outcomes were determined through 12/2005. Cox proportional hazards regression analyses were performed after adjusting for age, sex, race, T stage, grade, and primary site. Stage I-II cases were categorized by total LN examined (1–8, 9–12, and >12). Stage III cases were evaluated using cut-point analysis to determine the number of positive LN that predicted outcomes. This result was then compared to the predictive value of the ratio of positive to total LN (LNR) using the chi-square statistic. Results: 1,991 patients were identified in the SEER database. Survival among stage I/II patients (n=1,216) was dependent upon the total number of LN assessed. 5-year DSS for stage II patients was 66%, 82% (HR 0.52 95% CI .33-.84), and 88% (HR 0.38, 95% CI .23-.61) for 1–8, 9–12, >12 LN, respectively. The optimal cutpoint of positive LN for stage III disease (n=775) was <3 compard to ≥3 with 5 year DSS of 58% vs. 37% (HR 1.49, 95% CI 1.15–1.92, P=0.002), respectively. Among stage III patients, the LNR was even more predictive of survival than stratification by the number of positive lymph nodes as demonstrated by an improved chi-square statistic for the multivariate model (78.8 vs 63.1, P=0.0005). Conclusions: As noted in colon cancer, the total number of LN assessed has considerable influence upon survival in stage I, II and III small bowel adenocarcinoma. Stratifying stage III small bowel adenocarcinoma into those with <3 and ≥3 positive lymph nodes significantly improves prognostication for these patients and future staging systems should incorporate the number of positive nodes into nodal staging. The use of LNR may provide additional prognostic information. No significant financial relationships to disclose.