Cancer research has focused on the cancer cell, its proliferation rates, apoptosis resistance, mutation rates, sensitivity to radio and chemotherapy. However, tumor metastatic progression involves many other cellular and molecular players, the tumor microenvironment (TME). In the battle against cancer, to improve the survival and quality of life of metastatic patients, the key cancer supporting players must be identified and targeted. For a tumor to leave its primary site, it must invade the surrounding extracellular matrix, enter the blood or lymphatic circulation, survive in circulation, extravasate at the metastatic site, start proliferating in this new tissue, and during the entire process evade the immune system. In many instances, cancer cells co-opt physiologic niches and processes to survive and even thrive in hostile environments. This is not addressed in 2D monotypic cancer cell cultures. This collection aims to highlight the latest techniques in TME research and promote “multi-cellular” interdisciplinary approaches in the field of metastasis. The collection will cover but is not limited to:

 - 3D co-culture methods of cancer and supporting cells and matrices (culture and imaging, e.g. Single Plane Illumination Microscopy)

 - tumor microenvironment metabolomic studies

- tumor vasculature imaging techniques (animal models of angiogenesis, multiphoton confocal microscopy of vascularized primary tumors and metastases)

- immune cell modulation and exploitation by cancer cells (flow cytometry methods, adoptive transfer models, intra-vital microscopy)

- circulating and disseminating tumor cell (CTC and DTC) detection methods (including methods to detect the potential of dormant DTCs to reactivate)

- humanized and patient-derived animal models of metastasis and pre-metastatic niches.