Greater lymph node retrieval and lymph node ratio impacts survival in resected pancreatic cancer.

BACKGROUND: Surgical resection is the mainstay of pancreatic cancer treatment; however, the ideal lymphadenectomy remains unsettled. This study sought to determine whether number of examined lymph nodes (eLNs) and lymph node ratio (LNR) impact survival.

METHODS: The U.S. National Cancer Data Base (2003-2011) was reviewed for patients who underwent initial resection for clinical stage I and II pancreatic adenocarcinoma. Univariate and multivariate survival analyses were performed.

RESULTS: Of 14,007 patients, 15.6% had 0-6 eLN, 27.1% 7-12, 13.4% 13-15, and 38.6% > 15 eLN. Median eLN was 11 for pancreaticoduodenectomy, and 14 for distal, total pancreatectomy, or other procedure. ELN >15 was associated with significantly improved survival in both node negative and positive disease (P < 0.001, both). In multivariable analysis, 7-12, 13-15, and >15 eLN had improved survival relative to 0-6 eLN (HR 0.87, P < 0.001, HR 0.89, P = 0.002, HR 0.82, P < 0.001, respectively). A total of 34.5% of patients had an LNR of 0, 31.5% ≤ 0.2, 20.3% 0.2-0.4, 11.7% 0.4-0.8, and 2.0% had an LNR >0.8. Patients with LNR 0 had improved survival in T1-T3 disease (P < 0.01). In multivariable analysis, higher LNR was negatively associated with survival (LNR 0-0.2: HR 1.44, P < 0.001, LNR 0.2-0.4: HR 1.82, P < 0.001, LNR 0.4-0.8: 2.03, P < 0.001, LNR >0.8, P < 0.001). Even with suboptimal eLN (eLN ≤6 or ≤12), higher LNR remained an independent predictor of mortality.

CONCLUSIONS: Greater lymph node retrieval in stage I & II pancreatic adenocarcinoma may have prognostic value, even in node-negative disease. Lymph node ratio is inversely related to survival and may be useful with suboptimal eLN.