Animal studies have revealed that exercise-induced IL-6 secretion plays a crucial role in the mobilization and redistribution of NK cells towards tumor tissue, thereby decreasing tumor growth.227 However, these effects did not translate to humans, as indicated by two randomized controlled trials with prostate cancer patients.228,229 Future studies will have to clarify if these mechanism translate to other tumor entities to elucidate the therapeutic significance of IL-6R signaling in exercise-induced immune cell trafficking. Here, IL6 is linked to neoplasm.