Cancer-related Genomic Testing and Genetic Testing

Over the past few decades, researchers have learned a great deal about the thousands of different genes inside the cells in our bodies, how they interact with each other, and how many of these genes might be related to cancer.

You may have heard terms such as genomics (and genomic testing) and genetics (and genetic testing) and wondered what they mean. Here we’ll talk about these terms, how they’re related, and how they’re different, especially in the context of cancer.

What are genomics and genetics?

Genomics and genetics are related fields of study.

Genetics refers to the study of genes and their roles in inheritance – in other words, it’s about how genes affect the way that certain traits or conditions are hereditary, or passed down from one generation to another. Genetics focuses mainly on the study of individual genes and their effects. Genes are pieces of DNA in our cells that carry the instructions for making proteins, which direct the activities of cells and functions of the body.

Genomics is the study of a person's entire set of genes (their genome), including how these genes interact with each other and with the person's environment.

On a broad level, genomics is helping researchers learn more about the gene and protein changes inside different cancer cells. This is being used to develop newer cancer treatments aimed at these gene and protein changes. You can learn more about how changes in a cell’s genes can lead to cancer in Genes and Cancer.

Genomics is also becoming an important part of care for many people with cancer.

What is genomic testing?

When it comes to cancer, genomic testing most often refers to tests done to look at the genome (or parts of the genome) inside a person's cancer cells to learn about the gene or protein changes in these cells that make them different from normal cells.

For people with cancer, genomic testing of the cancer cells can often provide important information, such as how quickly the cancer is likely to grow, as well as if certain treatments (such as targeted therapy or immunotherapy drugs) are likely to be helpful in treating their cancer.

Genomic testing can go by many other names, including:

• Genomic profiling or genome sequencing
• Biomarker testing
• Tumor testing, tumor genetic testing, tumor marker testing, or tumor subtyping
• Molecular testing or molecular profiling
• Next generation sequencing

Testing is often done on a sample of the tumor (from a biopsy or surgery) if possible, but it might also be done using a sample of blood, saliva, or other body fluids.

Genomic testing might be used in other situations as well. To learn more about how genomic testing can be important for people with cancer, see:

• Biomarker Tests and Cancer Treatment
• Precision or Personalized Medicine

How is genetic testing different from genomic testing?

The term genetic testing can have different meanings, but when talking about cancer it most often refers to predictive genetic testing. This type of testing looks for certain changes in a person’s genes to see if they’ve inherited a change from a parent that affects their risk of cancer. These inherited gene changes are also called germline mutations.

Genetic testing is sometimes done in people with cancer. But unlike genomic testing, genetic testing is usually not done on cancer cells. It’s done on other cells in the body (such as cells from a blood or saliva sample). This is because the purpose of genetic testing is to see if a person has inherited a gene change from a parent (and therefore has the change in all the cells in their body).

To learn more about genetic testing as it relates to cancer risk, see Genetic Testing for Cancer Risk.