Molecular testing is a method that uses a sample of tissue, blood, or other body fluid to check for certain genes, proteins, or other molecules that may be a sign of a disease or condition, such as cancer.

Molecular testing can also be used to check for certain changes in a gene or chromosome that may increase a person’s risk of developing cancer or other diseases.

Molecular testing may be done with other procedures, such as biopsies, to help diagnose some types of cancer. It may also be used to help plan treatment, find out how well treatment is working, make a prognosis, or predict whether cancer will come back or spread to other parts of the body. Also called biomarker testing and molecular profiling.