Why early pathology input matters in biologically rich cancer trials.

Pathology is central to many biologically driven cancer clinical trials. Biomarker-led and translational studies depend on robust tissue pathways, cellular and molecular assays, pathology-derived endpoints, and clinically meaningful interpretation of discovery science. Where trials depend on tumour material, biomarker-defined eligibility or mechanism-focused endpoints, pathology expertise should be embedded early, before protocols, budgets, and assays are fixed. Early pathology input strengthens feasibility, specimen governance, assay selection, quality assurance, and the long-term value of collected samples. In the UK, the Clinical Trials Pathology Advisory Group, now within the new Pathological Society of Great Britain and Ireland Clinical Trials Pathology subcommittee, provides a practical route for pre-submission specialist review. This Perspective argues that pathology is core infrastructure for biologically rich trials, linking discovery science to clinical translation.