Histopathologic tumor invasion of superior mesenteric vein/portal vein is a poor prognostic indicator in patients with pancreatic ductal adenocarcinoma: results from a systematic review and meta-analysis

BACKGROUND: The impact of histopathologic tumor invasion of the superior mesenteric vein (SMV)/portal vein (PV) on prognosis in patients with pancreatic ductal adenocarcinoma (PDAC) after pancreatectomy remains controversial. A meta-analysis was performed to assess this issue. RESULTS: Eighteen observational studies comprising 5242 patients were eligible, of whom 2199 (41.9%) patients received SMV/PV resection. Histopathologic tumor invasion was detected in 1218 (58.1%) of the 2096 resected SMV/PV specimens. SMV/PV invasion was associated with higher rates of poor tumor differentiation (P = 0.002), lymph node metastasis (P < 0.001), perineural invasion (P < 0.001), positive resection margins (P = 0.004), and postoperative tumor recurrence (P < 0.001). SMV/PV invasion showed a significantly negative effect on survival in total patients who underwent pancreatectomy with and without SMV/PV resection (hazard ratio [HR]: 1.21, 95% confidence interval [CI]: 1.08-1.35; P = 0.001) and in patients who underwent pancreatectomy with SMV/PV resection (HR: 1.88, 95% CI, 1.48-2.39; P < 0.001). MATERIALS AND METHODS: A systematic literature search was performed to identify articles published from January 2000 to August 2016. Data were pooled for meta-analysis using Review Manager 5.3. CONCLUSIONS: Histopathologic tumor invasion of the SMV/PV is associated with more aggressive biologic behavior and could be used as an indicator of poor prognosis after PDAC resection.