The prognostic value of stroma desmoplasia in pancreatic ductal adenocarcinoma.

Abstract

211 Background: Pancreatic ductal adenocarcinoma (PDAC) often presents an abundant desmoplastic stroma. We assessed the prognostic value of stroma density and activity in patients with resectable PDAC treated with surgery and adjuvant gemcitabine-based chemotherapy. Methods: FFPE-tissue originating from the pancreatectomy of 145 patients was immunohistochemicallystained for haematoxylin-eosin and Masson’s trichrome to assess stroma density, and alpha-smooth muscle actin (αSMA) expression for activated pancreatic stellate cells. Their expression was correlated with clinicopathological characteristics as well as overall survival (OS), progression-free survival (PFS), local progression-free survival (LPFS) and distant metastases free-survival (DMFS). Results: After a mean follow-up of 20 months (range, 2-69 months), the median OS was 21 months and the 3-year OS was 35.7 %. In multivariate analysis, highly-dense stroma was an independent prognostic parameter for OS (p = 0.001), PFS (p = 0.007), LPFS (p = 0.001) and DMFS (p = 0.002), while αSMA expression lacked significance. Interestingly, highly-dense stroma retained significance for the four clinical endpoints only in early (pT1-2) but not late (pT3-4) stage tumors. Additionally, late pT-stage (pT3-4), the presence of lymph node metastases (pN+ vs pN0), perineural/neural invasion PNI and adjuvant chemotherapy also correlated with prognosis in multivariate analysis. Conclusions: In summary, stroma density represents an independent prognostic marker in PDAC patients treated with adjuvant chemotherapy. Our findings highlight the complexity of desmoplasia and indicate that highly-dense stroma is associated with better outcome. Further validation of the prognostic value of stroma as a biomarker and its role in PDAC biology is warranted and will be performed in a prospective study.