Pathology – Research and Practice 207 (2011) 487–491 Contents lists available at ScienceDirect Pathology – Research and Practice jo ur nal h omepage: www.elsevier.de/prp Original article Hematopoietic progenitor cells (HPCs) in node-negative invasive breast carcinomas: Immunohistochemical analysis and clinico-pathological correlations G. Giuffrè a , V. Adamo b , A. Ieni a , F. Colonese b , V. Barresi a , N. Caristi b , B. Adamo b , G. Tuccari a,∗ a Department of Human Pathology, Section of Pathological Anatomy, A.O.U. ‘Polyclinic G. Martino’, University of Messina, Italy b Department of Human Pathology, Section of Clinical Oncology, A.O.U. Polyclinic G. Martino, University of Messina, Italy a r t i c l e i n f o Article history: Received 31 January 2011 Received in revised form 1 April 2011 Accepted 30 May 2011 Keywords: Breast cancer Immunohistochemistry Stem cells Pre-metastatic niche Metastasis a b s t r a c t Using immunohistochemistry, we investigated 603 negative lymph nodes from 51 patients affected by invasive breast cancer (BC) to recognize bone marrow-derived hematopoietic progenitor cells (HPCs). HPC aggregates, revealed by CD34, CD133, VEGFR1, and CD117 antisera, were determined by an intensity- distribution score (ID). Cases with an ID-score >3 at least for one marker were considered to strongly express HPCs. Twenty-five of 51 (49%) high expressor patients were identified by CD34 antiserum, while 24/51 (47.1%), 17/51 (33.3%), and 15/51 (29.4%) were identified by CD117, CD133, and VEGFR1, respec- tively. No significant relationships were found between HPCs status and histotype, tumor grade, stage, and hormone receptors, as determined at the moment of the first diagnosis. A significant correlation was recorded for Ki-67 values, as well as for death from invasive BC. No statistical significance was achieved regarding HER2 status, although a tendency toward a statistically significant P value was obtained. A significant relationship (P < 0.001) was found between high expressors of HPC and progression of disease, documented by the development of distant metastases. An equivalent P value was ascertained for osseous localizations, with a lesser value in other metastatic sites. Regarding the appearance of distant metastases, the greatest efficiency value was obtained by CD133 (85.7%). Overall survival (OS) and distant metastases-free survival (DMFS) revealed a high statistical significance for HPC expression, Ki-67 values, and HER2 status. By multivariate analysis, HPC expression and Ki-67 values emerged as the higher independent prognostic variables in the analysis of DMFS and OS, respectively. © 2011 Elsevier GmbH. All rights reserved. Introduction Cancer metastases are responsible for the majority of cancer- related deaths as an event in which cells of the primary tumor acquire the ability to progress through sequential steps necessary for growth elsewhere [1–3]. In particular, breast cancer metasta- sis follows the sequence of local invasion, entry into vessels of the circulatory system, and subsequent deposition and growth at dis- tant sites [4]. Moreover, breast cancers (BC) have a predilection for metastasizing initially into regional lymph nodes [5,6]. However, axillary lymph node involvement has been considered one of the major factors in BC. Its assessment is relevant in clinical manage- ment and directly correlates with the final outcome [6–8]. In fact, although 80% of women with lymph node-negative invasive BC are expected to be alive and free of distant metastases at 10 years, ∗ Corresponding author at: Department of Human Pathology, Section of Patholog- ical Anatomy, A.O.U. “Polyclinic G. Martino”, Via Consolare Valeria, 98125 Messina, Italy. Tel.: +39 90 2212539; fax: +39 90 692650/2938324. E-mail address: tuccari@unime.it (G. Tuccari). about 20% of women with node-negative breast cancer develop metastases [6–8]. In BC, tumor cells circulating in peripheral blood and residing in bone marrow have been investigated for their role as marker of metastatic progression [9,10]. In bone marrow, hematopoietic stem cells are found in close association with osteoblasts, but they are able to migrate and to establish a relationship with the stromal microenvironment [11–13]. These bone marrow-derived clusters maintain their hematopoietic progenitor cell (HPC) status, and their recruitment represents an essential event in the process of metas- tasis [14], identifying sites of future metastases and representing a pre-metastatic niche [10,14,15]. In order to reveal the HPC clus- ters, VEGFR-1 (Flt-1) has been used as functional marker, even if detected in other normal cell types [16–18], as well as in neoplastic cells from melanoma, non-small cell lung carcinoma, prostate carci- noma, and breast cancer [19–22]. Nevertheless, it has been reported that subsets of VEGFR-1+ HPCs co-expressed the stem/progenitor cell antigens CD133, CD34, and CD117 [14]. However, tumor cells also spread via lymph nodes, preceding distant metastases to vis- ceral sites [23,24]. Since it has been underlined that principles of tumor hemangiogenesis, as well as lymphangiogenesis, are main- tained by VEGF family induction [25], we thought it might be 0344-0338/$ – see front matter © 2011 Elsevier GmbH. All rights reserved. doi:10.1016/j.prp.2011.05.013