Pfetin as a prognostic biomarker for gastrointestinal stromal tumor: validation study in multiple clinical facilities

The aim of this study is to confirm the prognostic value of pfetin in gastrointestinal stromal tumor patients. We recently reported the utility of pfetin, a novel prognostic biomarker in gastrointestinal stromal tumor. Gastrointestinal stromal tumor spans a wide spectrum from cases with curable disease to those with fatal tumors due to metastasis and recurrence. There is no biomarker predicting metastasis and/or recurrence of gastrointestinal stromal tumor though imatinib mesylate can improve recurrence-free survival.

Pfetin expression was examined in 40 gastrointestinal stromal tumor patients from the Juntendo University Shizuoka Hospital using immunohistochemistry. Correlations between immunohistochemical findings and clinicopathologic parameters were examined. The pfetin expression results were integrated with the clinicopathologic data in a total of 299 cases including our 40 new gastrointestinal stromal tumor cases and 259 others with previously reported data.

Immunohistochemical study demonstrated the disease-free survival rate to be 93.75% for pfetin-positive and 25.0% for pfetin-negative patients among the 40 cases from the Juntendo University Shizuoka Hospital (P= 0.0006). When all 299 cases were included, the disease-free survival rate was 92.44% for pfetin-positive and 60.81% for pfetin-negative patients (P< 0.0001). Both uni- and multivariate analyses revealed that, among the clinicopathologic parameters examined, only pfetin expression was an independent prognostic factor (P< 0.05).

These results confirm the possible clinical utility of pfetin as a prognostic biomarker for gastrointestinal stromal tumor. Pfetin appears to be a novel clinically applicable prognostic factor, which may be useful for deciding whether to administer imatinib mesylate or not.