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Background Several grading schemes for the extent of residual tumor in post-treatment pancreaticoduodenectomy (PD) specimens have been proposed. However, the prognostic significance of these grading schemes is unknown. Methods Histopathologic slides of 223 cases who received neoadjuvant chemoradiation and PD were reviewed. The extent of residual tumor was graded using both the College of American Pathologists (CAP) and the Evans grading systems. The grading results were correlated with clinicopathological parameters and survival. Results Among the 223 patients, 6 patients (2.7%) showed pathologic complete response (pCR, CAP Grade 0 or Evans grade IV), 36 cases (16.1%) with minimal residual tumor (CAP Grade 1 or Evans grade III), 124 cases (55.6%) with moderate response (CAP Grade 2 or Evans grade IIb) and 57 cases (25.6%) with poor response (CAP grade 3, 18 with Evans Grade I and 39 with Evans Grade IIa response). Patients with pCR or minimal residual tumor (response group 1) had better survivals than those with moderate and poor response (response group 2). Response group 1 patients had lower post-therapy tumor and AJCC stages, lower rates of lymph node metastasis, positive resection margin, and recurrence/metastasis. Grading the extent of residual tumor is an independent prognostic factor for OS in multivariate analysis. Conclusions pCR or minimal residual tumor in post-treatment PD specimens correlate with better survival in patients with PDAC who received neoadjuvant therapy and PD. Histologic grading of the extent of residual tumor in PD specimen is an important prognostic factor in patients with PDAC who received neoadjuvant therapies.

Perineural invasion (PNI) is one of the established prognostic factors in pancreatic ductal adenocarcinoma (PDAC). However, the prognostic significance of PNI in patients with PDAC who received neoadjuvant therapy and pancreaticoduodenectomy (PD) is not clear. In this study, we performed detailed examination of neural invasion in PD specimens from 212 patients with PDAC who received neoadjuvant chemoradiation (treated group) and 60 untreated patients at our institution between January 1999 and December 2007. The frequency of PNI was higher in untreated group (80%, 48/60) than the treated group (58%, 123/212). For the 123 treated cases that were positive for PNI, extra-tumoral PNI, intra-tumoral PNI, intra-pancreatic PNI only, extra-pancreatic PNI, and intra-neural invasion were identified in 86 (69.9%), 37 (30.1%), 11 (8.9%), 112 (91.1%), and 35 (28.5%) respectively. Presence of PNI correlated with tumor size, margin status, lymph node metastasis, pathologic tumor and AJCC stages in the treated group. Tumor involvement of nerves >0.8 mm correlated with higher frequency of positive margin compared to those with PNI involving nerves ≤0.8 mm, but not with other clinicopathologic parameters and survival. In treated group, the presence of PNI or intra-neural invasion correlated significantly with shorter disease-free survival (DFS) and overall survival (OS) compared to those with no PNI or PNI only respectively. PNI was an independent prognostic factor for both DFS and OS in multivariate analysis. Our results showed that PNI plays an important role in the progression of PDAC and in predicting the prognosis in this group of patients.

BACKGROUND The receptor tyrosine kinase Axl has been reported to be overexpressed in a variety of human cancers. Although previous studies have identified the role of Axl in the transformation, proliferation, survival, and invasion in cancers, the expression and functions of Axl in pancreatic cancer have not been studied in detail. METHODS The expression of Axl protein in 12 pancreatic cancer cell lines and 54 patient samples of stage II pancreatic ductal adenocarcinoma (PDA) and their paired non-neoplastic pancreatic tissue samples were examined. Using univariate and multivariate analysis, Axl expression was correlated with survival and other clinicopathologic features. To examine Axl functions in PDA, the effects of Axl knockdown on the invasion ability and radiation-induced apoptosis in PDA cell lines were measured. RESULTS Axl was overexpressed in 38 of 54 (70%) stage II PDA samples and 9 of 12 (75%) PDA cell lines. Axl overexpression was associated with higher frequencies of distant metastasis and poor overall and recurrence-free survivals (P = .03 and P = .04, respectively) independent of tumor size and stage or lymph node status in patients with stage II PDA. Knockdown of Axl expression in PDA cells abolished Gas6-mediated Akt activation, decreased invasion, and increased radiation-induced PARP cleavage and the percentage of apoptosis. CONCLUSIONS This study showed that Gas6 and Axl are frequently overexpressed in PDA cells and are associated with a poor prognosis in patients with stage II PDA. Axl promotes the invasion and survival of PDA cells. Therefore, targeting the Axl signaling pathway may represent a new approach to the treatment of PDA.

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