What spatial omics is teaching us about field cancerisation in prostate and bladder cancer.

BACKGROUND AND OBJECTIVES Field cancerisation is the process that results in a group of cells acquiring some of the phenotypic changes of cancer prior to transformation into cancer. Clinically, an important challenge remains the ability to distinguish clonal lineages and microenvironments within cancerised fields that will remain indolent from those that will progress to malignant transformation. Spatial 'omics' can help us investigate genetic, epigenetic, transcriptomic, proteomic, and cellular microenvironments that transform normal cells into a cancerised field, and subsequently into cancer. In this review, we will discuss how spatial omics techniques have expanded our understanding of field cancerisation in prostate and bladder cancer, and the challenges associated with this research. METHODS We identified key articles relating to field cancerisation in bladder and prostate cancer. Special emphasis was placed on studies that used modern spatial profiling technologies and studies that were designed to investigate changes within normal tissue rather than simply using it as a control for tumour tissue. RESULTS Spatial omics research into field cancerisation has identified interesting early findings that have informed our understanding of: transformation of the benign epithelium and mechanisms of intra-prostatic clonal expansion for prostate cancer; clonal expansion within the normal urothelium; mutations that are unique to cancerised fields within the bladder; and how field cancerisation may prime the urothelium for cancer transformation. CONCLUSIONS Spatial omics profiling of field cancerisation can inform risk stratification and personalised treatment options. However, there are a number of challenges associated with the technologies that must be overcome before the potential of spatial omics can be fully realised in clinical practice.