CD8A and cancer: Notably, almost every single melanoma cell in the micrometastasis was in close proximity to these T<sub>RM</sub>-like cells.<h4>Conclusion</h4>Such results support the emerging concept that CD103<sup>+</sup> CD8<sup>+</sup> T<sub>RM</sub> cells are key mediators of cancer surveillance and imply an important function of these cells in controlling clinically occult micrometastases in humans.