Risk Factors of the Recurrences of Pancreatic Solid Pseudopapillary Tumors: A Systematic Review and Meta-analysis

Abstract

Background: Pancreatic solid pseudopapillary tumors (SPTs) are rare neoplasms with low-grade malignancy. The main treatment for them is surgical resection. However, some SPTs relapse after resection. The risk factors associated with the recurrences of resected SPTs remain controversial to date. We performed a systematic review and meta-analysis to identify the risk factors of the recurrences of pancreatic SPTs. Materials and Methods: We searched PubMed, EMBASE, and the Cochrane Library from their inception to December 2017. Studies that focused on the risk factors of postoperative relapses of pancreatic SPTs were enrolled. Combined ORs with 95% CIs were calculated to evaluate the effects of relevant factors investigated in eligible studies. Heterogeneity among combined results was assessed by Cochran's Q test and by the degree of inconsistency (I²). Statistical analyses were performed by Review Manager (version 5.3) using random effects models. Results: We included 10 studies, which enrolled 1091 patients. The pooled results suggested that patients with larger tumors (diameter > 5cm), lymphovascular invasion, lymph node metastasis, synchronous metastasis and positive margin were prone to suffer from the recurrences of SPTs. In addition, some factors like gender, location of tumors, perineural invasion, calcification and capsular invasion did not show any correlation with the relapses of resected SPTs. Conclusion: Factors including a larger tumor size (diameter > 5cm), lymphovascular invasion, lymph node metastasis, synchronous metastasis and positive margin may increase the risk of recurrences of resected pancreatic SPTs. All SPTs should be excised and patients with high-risk features should undergo a long-term follow-up.

Keywords: pancreatic solid pseudopapillary tumors; recurrence; risk factors.

Figure 1

The flowchart of literature searching and selection.

Figure 2

Forest plots of association between relevant factors and recurrence of SPT. A: the association between the recurrence of SPT and gender. B: the association between the recurrence of SPT and tumor size (diameter > 5 cm). C: the association between the recurrence of SPT and tumor size (diameter > 8 cm).

Figure 3

Forest plots of association between relevant factors and recurrence of SPT. A: the association between the recurrence of SPT and location. B: the association between the recurrence of SPT and lymphovascular invasion. C: the association between the recurrence of SPT and perineural invasion.

Figure 4

Forest plots of association between relevant factors and recurrence of SPT. A: the association between the recurrence of SPT and calcification. B: the association between the recurrence of SPT and lymph node metastasis. C: the association between the recurrence of SPT and synchronous metastasis.

Figure 5

Forest plots of association between relevant factors and recurrence of SPT. A: the association between the recurrence of SPT and positive margin. B: the association between the recurrence of SPT and capsular invasion.

Figure 6

Funnel plots for publication bias. A: the funnel plot of gender. B: the funnel plot of tumor size (diameter > 5 cm). C: the funnel plot of tumor size (diameter > 8 cm). D: the funnel plot of location. E: the funnel plot of lymphovasular invasion. F: the funnel plot of perineural invasion. G: the funnel plot of calcification. H: the funnel plot of lymph node metastasis. I: the funnel plot of synchronous metastasis. J: the funnel plot of positive margin. K: the funnel plot of capsular invasion.