Introduction: Stress has been accompanying human beings since the beginning of their existence, worsening after Industrial Revolution. Due to current circumstances, stress is much discussed, however, it is restricted to psychosocial problems and rarely related to organic diseases such as cancer. According to Instituto Nacional de Câncer, by the end of 2022 approximately 2 million new cancer cases will be diagnosed in Brazil. Objective: Understand stress consequences on immune system correlating with tumorigenesis. Methods: Searches on SCIELO, LILACS, PubMed, BIREME and Academic Google databases, using as descriptors “Stress Physiology”; “Stress Influence on immune system”; “Immunovigilance”; "Basic tumor immunology;" “Immune surveillance”; “Tumor microenvironment”; “Immunosuppression by stress”; “Psychoneuroimmunology”. Results: Tumorigenesis is defined as malignant mutations accumulation characterized by exacerbated cell multiplication. To prevent this pathological state from materializing the organism has physiological barriers, the first is found in the cell cycle, where at certain points DNA quality is evaluated, when not approved the division is interrupted. If these mechanisms fail, immune system recognizes and destroys the mutant cell. Deficient immune response causes altered cells to develop escape mechanisms. In this context, stress is cited as an important immunosuppressant. Studies show deleterious effects of glucocorticoids on leukocytes, in Th1/Th2 responses imbalances and instability in humoral response. Conclusion: Ineffective immune response is a major contributor to tumorigenesis, which is vulnerable to stress and hormones released in this state.

Keywords : Psychological Stress; Neoplasms; Immunologic monitoring; Psychoneuroimmunology