Comparable prevalence of distant metastasis and survival of different primary site for LN + pancreatic tumor.

Background: Few studies have delved into the prevalence of distant metastasis (DM +) and survival for patients with lymph node metastases (LN +) by primary site. We aimed to detect differences in distant metastasis and prognosis between pancreatic head and bodytail tumors for LN + patients.

Methods: Patients with chemotherapy, histologically diagnosed, primary site between 2004 and 2016 were included from the SEER (Surveillance, Epidemiology, and End Results) database. Pancreatic head tumors were compared with pancreatic bodytail tumors using the odds ratio (OR) for rates of distant metastasis, hazard ratios (HR) for overall survival (OS) and cancer-specific survival (CSS). The competing risk model and propensity score matching (PSM) were performed to further explore.

Results: Of 5726 LN + patients identified from the SEER database, pancreatic head tumors account for 85.2% (4877 of 5726) and 14.8% (849 of 5726) were pancreatic bodytail tumors. The incidence of DM was lower in pancreatic head than in pancreatic bodytail tumors (OR, 0.29; 95% CI 0.23-0.37; P < 0.001). The multivariate Cox regression show pancreatic head tumors have a significantly shorter survival rate relative to pancreatic bodytail (HR, 1.12; 95% CI 1.03-1.22; P = 0.008), but the primary site was not a significant independent risk factor for prognosis by log-rank test (P = 0.39) and multivariate competing risk model [subdistribution HR (SHR), 1.08; 95% CI 0.98-1.19; P = 0.087].We then examined our conclusion by 1:1 propensity score matching, and the result reflected pancreatic head tumors have a lower risk of DM compared with pancreatic bodytail tumors (OR, 0.22; 95% CI 0.15-0.34; P < 0.001), but the primary site of pancreatic tumors was not associated with LN + patient survival based on univariate Cox regression (HR, 1.04; 95% CI 0.93-1.17; P = 0.435) and competing risk analysis (SHR, 1.01; 95% CI 0.89-1.12; P = 0.947).

Conclusions: LN + pancreatic head tumors were significantly lower risk of DM relative to pancreatic bodytail tumors. Survival outcome in LN + pancreatic tumors didn't exist significant differences split by primary site, which indicates that the prognosis of LN + patients with chemotherapy isn't associated with the primary site of metastasis, but with the occurrence of metastasis.