Formation and remodeling of immunological niches in solid tumors: organ-specific architectures, inflammatory parallels, and therapeutic reprogramming
Tumor immunity is increasingly understood not only through the cellular composition of the tumor microenvironment, but also through spatially organized local niches that can help determine where immune recognition is initiated, constrained, suppressed, or therapeutically restored. This review develops an organ-conditioned and evidence-graded framework for tumor immunological niches as spatially localized, interaction-dependent, functionally consequential, and dynamically remodeled units. Rather than reproducing a general taxonomy of cancer immune niches, we focus on how shared niche-forming mechanisms are implemented differently by organ-specific tissue rules. We first distinguish the niche concept from broad tumor microenvironment descriptions, immune infiltration, immune compartments, and tertiary lymphoid structures. We then propose an operational evidence hierarchy that separates spatial association, recurrent interaction, functional consequence, perturbation-based validation, and therapeutic actionability. Next, we synthesize core mechanisms of niche formation, including tumor-intrinsic signaling, stromal and extracellular-matrix scaffolding, chemokine and cytokine wiring, vascular-hypoxic-metabolic boundaries, myeloid-centered suppression, and tissue-resident immune imprinting. Brain and lung tumors are treated as two organizing paradigms: immune-restricted niche architecture in the central nervous system and inflammation-primed niche architecture in the lung. Oral, liver, and pancreatic tumors are discussed comparatively to show how mucosal-microbial, tolerogenic-metabolic, and desmoplastic immune-exclusion rules reshape shared niche mechanisms. We further separate tumor-specific evidence, inflammatory analogies, and hypothesis-generating parallels to avoid overextending chronic inflammation or fibrosis models. Finally, we examine how niche architecture produces T-cell exclusion, antigen-presentation failure, suppressive myeloid-stromal feedback, and therapeutic resistance, and how release, access, and licensing strategies may guide organ-tailored combinations when supported by adequate evidence. This review argues that tumor immunological niches may serve as meso-level analytical units linking spatial organization, organ context, evidence strength, inflammatory parallels, and therapeutic vulnerability when their evidentiary status is explicitly defined.