Cancer biomarkers are measurable indicators that provide information about the presence, type, or behavior of a tumor. They can be molecules produced directly by cancer cells or by the body in response to the tumor, and include DNA mutations, RNA expression patterns, proteins, metabolites, and features visible on medical images.

Genetic and genomic biomarkers such as specific mutations, gene fusions, or patterns of gene expression help classify cancers and predict response to targeted therapies. Examples include mutations in genes controlling cell growth and DNA repair, and signatures that indicate sensitivity or resistance to certain drugs. Epigenetic changes, like abnormal DNA methylation, are also being explored as biomarkers for early detection and prognosis.

Proteins in blood or other body fluids are widely studied because they can be measured noninvasively and repeatedly. Panels of multiple proteins often perform better than single markers, improving sensitivity and specificity. Emerging work in metabolomics examines small molecules produced by cancer altered metabolism to distinguish malignant from healthy states.

Another active area is liquid biopsy, where circulating tumor DNA, tumor cells, or extracellular vesicles are analyzed from blood samples. These can reveal tumor genetics in real time, track treatment response, and detect minimal residual disease or early relapse.

Imaging biomarkers use advanced analysis of radiologic scans to extract quantitative features that correlate with tumor biology and clinical outcomes. Increasingly, research focuses on integrating different classes of biomarkers into multiomic profiles, combined with artificial intelligence, to refine diagnosis, guide personalized treatment, and monitor disease with greater precision while minimizing invasive procedures.