Markers of fibroblast-rich tumor stroma and perivascular cells in serous ovarian cancer: Inter- and intra-patient heterogeneity and impact on survival

Inter- and intra-patient variations in tumor microenvironment of serous ovarian cancer are largely unexplored. We aimed to explore potential co-regulation of tumor stroma characteristics, analyze their concordance in primary and metastatic lesions, and study their impact on survival. A tissue microarray (TMA) with 186 tumors and 91 matched metastases was subjected to immunohistochemistry double staining with endothelial cell marker CD34 and fibroblast and pericyte markers alpha-SMA, PDGF beta R and desmin. Images were digitally analyzed to yield metrics related to vasculature and stroma features. Intra-case analyses showed that PDGF beta R in perivascular cells and fibroblasts were strongly correlated. Similar findings were observed concerning `-SMA. Most stroma characteristics showed large variations in intra-case comparisons of primary tumors and metastasis. Large PDGF beta R-positive stroma fraction and high PDGF beta FR positive perivascular intensity were both significantly associated with shorter survival in uni- and multi-variate analyses (HR 1.7, 95% CI 1.1-2.5; HR 1.7, 95% CI 1.1-2.8). In conclusion, we found PDGF beta R- and alpha-SMA-expression to be largely independent of each other but concordantly activated in perivascular cells and in fibroblasts within the primary tumor. Stromal characteristics differed between primary tumors and metastases. PDGF beta R in perivascular cells and in fibroblasts may be novel prognostic markers in serous ovarian cancer.