Impact of tumor size on survival of patients with resected pancreatic ductal adenocarcinoma: a systematic review and meta-analysis

BACKGROUND: The impact of tumor size on prognosis for surgically treated patients with pancreatic ductal adenocarcinoma (PDAC) remains controversial. A systematic review and meta-analysis was performed to evaluate this issue. METHODS: Relevant studies published from January 2000 to June 2017 were identified through EMBASE and PUBMED. Data were pooled for meta-analysis using Review Manager 5.3. RESULTS: Twenty eight observational studies involving a total of 23,945 patients were included. Tumors > 2 cm was associated with poor prognosis: the pooled hazard ratio (HR) estimate for overall survival was 1.52 (95% confidence interval [CI]: 1.41–1.64; P < 0.0001) by univariate analysis and 1.61 (95% CI: 1.35–1.91; P < 0.0001) by multivariate analysis; the pooled HR estimate for disease-free survival was 1.74 (95% CI: 1.46–2.07; P < 0.0001) by univariate analysis and 1.38 (95% CI: 1.12–1.68; P = 0.002) by multivariate analysis. When compared with patients with tumors ≤2 cm, those with the tumors > 2 cm had higher incidences of lymph node metastasis, poor tumor differentiation, lymph vessel invasion, vascular invasion, perineural invasion, and positive intraoperative peritoneal cytology. CONCLUSION: These data demonstrate that PDAC size > 2 cm is an independent predictive factor for poor prognosis after surgical resection and associated with more aggressive tumor biology.