Architecture sets the path: Breast cancer subtypes differently shape the early brain metastatic niche.

The ability of disseminated cancer cells to colonize the brain is highly dependent on initial survival cues, often evoking early microenvironmental adaptations. In this issue of Cancer Cell, Gan et al. unveil disparate tumor architectures in early stage HER2+ breast cancer and triple-negative breast cancer brain metastases that shape stromal interactions, providing a rationale for subtype-dependent patient stratification.