As incoming Editor-in-Chief (Europe) for Clinical & Experimental Metastasis, I would like to take this opportunity to thank my predecessor, Dr. Sue Eccles, who served for an amazing 32 years as Editor-in-Chief. She has done an admirable job in establishing the journal as the official organ of the Metastasis Research Society, and sustaining the journal over recent years during the sometimes turbulent developments in scientific publishing. Well done Sue! I will try to do my best to follow in your footsteps.

Taking over the reins as Editor-in-Chief provides an excellent opportunity to look back over the articles that have been published by Clinical & Experimental Metastasis in the past few years, and to identify those that have made the most impact on the field. Such an analysis is instructive in showing where the journal is positioned in metastasis research field, and provides guidance on how to the steer the journal in the future.

As the title of the journal suggests, Clinical & Experimental Metastasis aims to publish both laboratory-based basic research, as well as studies on human cancer patients. It is striking that the majority of the most highly cited articles provide functional evidence for important molecular mechanisms that are required for different processes in metastasis, and often address common themes. For example, the regulation of the immune system and its contribution to metastasis is a major theme amongst well-cited papers published in Clinical & Experimental Metastasis in 2014, in particular the role of cytokines, chemokines and their receptors in regulating both the metastasis-relevant properties of tumor cells themselves, as well as key cells in the microenvironment such as hematopoietic cells [1–4]. Several frequently cited papers from 2014 focus on the contribution of invasiveness to metastasis development and poor prognosis [5, 6], and the underlying molecular mechanisms that determine patient outcome [7], such as the epithelial-mesenchymal transition (EMT) [8]. Finally, papers describing novel biomarkers that can be used to assess metastatic potential for ovarian cancer [9] and clear cell renal carcinoma [10] have also been well cited.

It is also enlightening to look at the other end of the spectrum, namely papers published in Clinical & Experimental Metastasis that have had relatively little impact on the field. Of these, a significant proportion were correlative clinical studies with relatively small numbers of patients. The majority of laboratory-based experimental papers that received little attention from the metastasis research community used only in vitro analyses with cultured cells lines, and did not provide validation of findings using relevant in vivo animal models of metastasis.

Based on these analyses, the editors on Clinical & Experimental Metastasis have decided to modify the scope and aims of the journal, in order to ensure that the journal reflects current research trends, and focuses on topics of most relevance for the field. Specifically, case studies and meta-analyses will not generally be published. Correlative clinical studies with small numbers of patients will need to contain experimental validation of the findings. Experimental and laboratory-based research will need to provide a significant advance in knowledge, and should contain mechanistic functional insights. Validation in experimental animal models of findings made with cell lines will generally be expected.

In summary, this brief selection of the most highly cited articles in Clinical & Experimental Metastasis from 2014 provides a valuable insight into recent trends in the field, and also identifies the strengths of the journal. I look forward to building on these strengths as Editor-in-Chief, and to developing the standing and impact of the journal within the scientific community. Please join with me in this endeavor and submit your best scientific articles to the journal. The editors of Clinical & Experimental Metastasis also warmly welcome initiatives to set up special thematic issues, for example review series on specific metastasis-related topics. Similarly, suggestions for review articles are always very welcome. We look forward to hearing from you.

Jonathan Sleeman

Editor-in-Chief (Europe)