Prognostic value of Ki-67 in solid pseudopapillary tumor of the pancreas: Huashan experience and systematic review of the literature

Background. Solid pseudopapillary tumor of the pancreas (SPTP) is considered to have a low Ki-67 proliferation index, which may explain the generally good clinical outcome. The aim of our study was to evaluate whether Ki-67 has prognostic value in SPTP. Methods. A case series study of patients with SPTP treated in our institution from June 2002 to April 2014 was conducted. Prognostic factors for clinical outcomes were analyzed by the use of clinical decision and survival analysis. In addition, we performed a systematic review and pooled analysis to evaluate our results. Results. The institutional data included 71 patients (13 male and 58 female) ranging in age from 12 to 64 years (median, 31 years). Three patients developed local recurrence and/or liver metastasis after initial surgery. The 5-year recurrence-free survival rate was 93.6 %. One patient died of disease, with the 5-year disease-specific survival rate of 98.5 %. Ki-67 index >= 4% was found significantly associated with the survival of SPTP. Twenty-six studies comprising 163 patients were included in the pooled analysis based on our inclusion criteria. A total of 15 cases showed a Ki-67 index >= 4%. Kaplan-Meier survival analysis confirmed that Ki-67 index >= 4 % was significantly associated with poorer recurrence free survival and disease-specific survival (both P <.001). Conclusion. This study highlighted a potential role of Ki-67 in predicting adverse outcome of patients with SPTP and should be considered as part of routine histological reporting of SPTP.