Podoplanin-positive Cancer-associated stromal fibroblasts in primary tumor and synchronous lymph node metastases of HER2-overexpressing breast carcinomas

Abstract

We compared the status of stromal podoplanin-positive cancer-associated fibroblasts (ppCAFs) between primary tumors and paired synchronous lymph node metastases (LNMs) and analyzed the prognostic significance of tumoral ppCAFs in 203 patients with human epidermal growth factor receptor 2-positive breast carcinoma. ppCAFs were found in 167/203 and in 35/87 tumors and LNM, respectively. ppCAFs were most frequently found in tumors and corresponding LNM (n=52, 59.8%; p=0.001). However, for all LNMs (n=12) without ppCAFs, their paired tumors also lacked ppCAFs. In both tumors and LNMs, ppCAFs were α-smooth muscle actin-positive and cluster of differentiation 21 protein-negative, suggesting them not to be resident lymph node cells. Moreover, in our series, the presence of ppCAFs in tumors was borderline related to poor disease-free survival (p=0.058). These results speak in favor of a hypothesis suggesting ppCAFs accompany metastatic cancer cells migrating from tumor to LNMs.