[At the crossroads of cancer].

Since the introduction of the concept of immunosurveillance in 1970 by Macfarlane Burnet and Lewis Thomas, cancer immunology has known a significant revolution and an explosion of discoveries. In this regard, manipulation of the immune system in cancer pathology has been a succession of enthusiasms and failures. Thanks to the fundamental achievements during the past three decades, non-specific passive immunotherapy of cancer has shifted to active specific immunotherapy. Thanks to the immunological arsenal (tumor peptides, dendritic cells), the clinical trials have increased but the results were not encouraging. It became clear that the escape of immunosurveillance by tumor cells is under the control of the complex tumor microenvironment and its heterogeneity, complexity and plasticity. The future of immunotherapy lies in an integrative approach to simultaneously boost the immune system and target the tumor microenvironment or combine immunotherapy with conventional treatments. In this review, we will focus on the development of cancer immunotherapy, its realities, failure and hope it raises as the fourth modality of cancer therapy.