Biomarker-Based Linkages between Infection and Oncology for Translational Decision Support

Infectious disease and oncology maintain separate biomarker ecosystems and separate decision-support tools, yet they increasingly share molecular substrates, analytical platforms, diagnostic problems, and causal biology. This narrative review examines developments connecting the two fields: Host-response protein signatures moving into deployed use, plasma cell-free DNA emerging as a shared substrate as microbial sequencing entered formal diagnostic criteria while tumour-derived sequencing entered adjuvant treatment decisions, circulating viral tumour DNA functioning simultaneously as an infection and a cancer marker, and a published critique of reproducibility in the cancer microbiome literature. These are considered alongside evidence on diagnostic infrastructure, data governance, model oversight, health system financing and workforce capability, supply integrity, and population surveillance, which prior reviews have treated separately. Read together, they identify an integration that is technically available but unimplemented, since the same plasma specimen can yield both microbial and tumour-derived results that are nonetheless generated and interpreted in isolation. The constraints are evidentiary, infrastructural, and governance-related rather than analytical.