Background: Solid pseudopapillary tumors (SPTs) of the pancreas are still considered a surgical enigma. Many clinical research trials have failed to identify prognostic factors that predict the malignant behavior of SPTs.
Materials and methods: This work was a retrospective multicenter study that included a total of 17 medical institutions. Data from 351 patients who underwent surgical resection from January 1990 to December 2008 were retrospectively collected using standardized case report forms requesting clinicopathologic features.
Results: Thirty-four patients (9.7%) were male, and 317 (90.3%) were female, with a mean age of 36.8 ± 12.4 years. Recently, minimally invasive (P < 0.001) and parenchyma or function-preserving limited surgeries (P = 0.016) have been more frequently applied for the treatment of pancreatic SPTs. Ninety-eight patients (27.9%) had microscopic malignant features. Only 9 patients (2.6%) experienced tumor recurrence after the initial pancreatic SPT resection. Multivariate analysis showed that a tumor size larger than 8 cm [Exp (β) = 7.385, P = 0.018], microscopic malignant features [Exp (β) = 10.009, P = 0.011], and stage IV [Exp (β) = 42.003, P = 0.002] were significant prognostic factors for tumor recurrence. When combined with stage IV, the microscopic malignant features and 2010 World Health Organization definition of solid pseudopapillary carcinoma more successfully differentiated future recurrence risk groups (P < 0.001).
Conclusions: More specific pathologic descriptions need to be employed in pathologic report forms to provide proper information to predict SPT recurrence after resection. Future studies emphasizing the standardized pathologic evaluation of pancreatic SPTs may unveil the enigmatic nature of pancreatic SPTs.