Cancer Biomarkers by Cancer Type

Different cancers are driven by different biological mechanisms. As a result, the biomarkers doctors test for—and how much those results affect treatment—vary widely by cancer type.

This page provides a high-level, patient-friendly overview of commonly tested biomarkers, what they are used for, and why they matter.

Important: Not every patient will have actionable biomarkers. That is normal and does not mean effective treatment options are limited.

Lung cancer (especially non–small cell lung cancer)

Lung cancer is one of the most biomarker-driven cancers today.

Common tumor biomarkers

  • EGFR – predicts response to EGFR-targeted therapies
  • ALK – gene rearrangement; targeted therapy available
  • ROS1 – similar to ALK; targeted therapy available
  • BRAF – certain mutations are targetable
  • KRAS (especially G12C) – targetable in selected settings
  • MET (exon 14 skipping) – targetable in selected cases
  • RET – gene fusion; targeted therapy available
  • NTRK – rare but actionable across cancer types

Immune-related

  • PD-L1 expression – helps guide immunotherapy use

Notes

  • Small cell lung cancer has far fewer actionable biomarkers.
  • Many patients will not have a targetable alteration—and that is expected.

Breast cancer

Breast cancer is primarily defined by receptor status, not long mutation lists.

Core biomarkers (almost always tested)

  • Estrogen receptor (ER)
  • Progesterone receptor (PR)
  • HER2

These define the main subtypes:

  • HR+ / HER2-
  • HER2+
  • Triple-negative (ER-/PR-/HER2-)

Additional biomarkers in selected settings

  • Ki-67 – proliferation marker (context-dependent)
  • PD-L1 – mainly in certain triple-negative cancers
  • BRCA1 / BRCA2 – tumor and/or inherited
  • PIK3CA – may influence targeted options in some HR+ cancers

Colorectal cancer

Biomarkers are critical for selecting and avoiding certain therapies.

Core biomarkers

  • MMR / MSI status
  • MSI-H / dMMR → immunotherapy sensitivity
  • MSS → immunotherapy usually less effective

Common mutation testing

  • KRAS
  • NRAS
  • BRAF

These help guide targeted therapy decisions and avoid ineffective treatments.

Less common

  • HER2 amplification
  • NTRK fusions (rare)

Prostate cancer

Historically less biomarker-driven, but increasingly important in advanced disease.

Commonly evaluated

  • BRCA1 / BRCA2 (tumor and/or inherited)
  • Other DNA repair genes (often grouped clinically)

Notes

  • PSA is a monitoring marker, not a treatment-selection biomarker.
  • Most decisions still rely on stage, grade, and response to therapy.

Ovarian cancer

Biomarkers often relate to DNA repair pathways.

Commonly tested

  • BRCA1 / BRCA2 (tumor and inherited)
  • Homologous recombination deficiency (HRD) status

Additional

  • MMR / MSI (less common but relevant if present)

These results can influence maintenance strategies and later-line options.

Endometrial (uterine) cancer

Increasingly guided by molecular classification.

Common biomarkers

  • MMR / MSI status
  • POLE mutations (selected cases)
  • p53 status

These help refine prognosis and guide treatment intensity.

Pancreatic cancer

Fewer actionable biomarkers, but important exceptions exist.

Commonly considered

  • BRCA1 / BRCA2 and other DNA repair genes
  • MMR / MSI (rare but important)
  • NTRK fusions (very rare)

Most treatment decisions still rely on stage and response to therapy.

Brain tumors (gliomas)

Highly molecularly defined, but fewer drug targets.

Core molecular markers

  • IDH mutation status
  • 1p/19q codeletion
  • MGMT promoter methylation
  • ATRX, TP53 (classification context)

These markers define tumor subtype and prognosis more than drug selection.

Bladder cancer

Biomarkers increasingly refine systemic therapy choices.

Commonly evaluated

  • PD-L1 (context-dependent)
  • FGFR alterations (subset of patients)
  • Tumor mutational burden (TMB) (contextual)

Depth of invasion remains the primary driver of treatment decisions.

Blood cancers (high-level overview)

Biomarkers often define the disease itself.

Examples

  • BCR-ABL – chronic myeloid leukemia
  • FLT3, NPM1 – acute myeloid leukemia
  • CD19, CD20 – lymphomas (guide antibody therapies)

Testing is highly subtype-specific.

How to use this information

A helpful way to frame biomarker testing is to ask:

  • Which of these biomarkers were tested in my case?
  • Which results actually change treatment decisions?
  • Which results are informative but not actionable right now?
  • Should testing be repeated later?

Understanding this helps patients engage without unnecessary anxiety.

Last reviewed: 2026-02-01