Embracing diversity: macrophage complexity in cancer

Macrophages are myeloid cells that receive, integrate, and respond to tumoral cues. Tumors evolve and are shaped by macrophages, with tumor-associated macrophage (TAM)-tumor sculpting capacities going beyond an increase in their cellular mass. Longitudinal and local heterogeneity of TAM states is now possible with the use of single-cell and spatial transcriptomics. However, understanding TAM biology and its fundamental functional programs is still challenging, probably because of the lack of models that fully integrate TAM complexity. Here, we aim to review TAM diversity not only at the level of single-cell phenotypes but also by integrating complex physiological signals that determine their complexity and plasticity in tumors.