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What's the difference? Genetics vs genomics

genetics genomics
Although commonly used interchangeably, the terms “genetics” and “genomics” are not synonyms.

Although commonly used interchangeably, the terms “genetics” and “genomics” are not synonyms. Both involve the study of genetic material and both are derived from the Greek word gen, which means birth or origin. But the similarities largely end there. Though genetics and genomics are each complex topics, the difference between them is much simpler: One (genetics) refers to a person’s genetic makeup, and the other (genomics) is typically used in reference to a tumor’s molecular composition. You can also think about genetics in terms of inherited traits and genomics in terms of cancer-specific mutations.

What they are

Genetics is the study of the genes people inherit at birth, passed on from their family through the generations. Every cell in the human body has a complete strand of DNA, and each strand is packed with genes, which carry instructions for certain traits, such as blue eyes, red hair—or, perhaps, a stronger likelihood of certain cancers. Genetic tests may help identify a person’s risk of cancer and other diseases.

Genomics generally refers to the study of mutations in genes that may drive various cancer behaviors, from how aggressive it is to whether it spreads to distant locations in the body. Each cell in the human body contains tens of thousands of genes, but mutations in just a single gene may cause cells to grow out of control and lead to tumor growth. Often, the cells in a tumor change over time because their genes continue to mutate. So a genomic test may vary widely over time, even when conducted on the same tumor. When the tumor’s molecular structure changes, the patient may develop resistance to a certain treatment. “Cancer is, unfortunately, very smart, and it’s common to have a treatment stop working because the cancer is now a different cancer,” says Melanie Corbman, Licensed Certified Genetic Counselor at our hospital in Philadelphia.

What the tests show

Both tests—those mapping a person’s DNA profile and those analyzing a tumor’s genomic abnormalities—may be helpful in treating cancer, though genetic and genomic testing are used in very different ways and in very different circumstances. In the cancer world, genetic testing looks for genetic mutations that the patient may have inherited through his or her family, which is why it’s often recommended for people who have a family history of a certain type of cancer. Those who test positive for the BRCA1 gene mutation, for example, have a higher risk of developing breast and ovarian cancer.  

Genomic testing is used to identify mutations that have nothing to do with heredity but instead occur within the cancer cell itself, either due to an external cause, such as tobacco use or sun exposure, or an internal factor, such as a random molecular change within the cell. These changes may determine why the tumor behaves the way it does—why it grows or spreads, for example. If the mutation matches a known abnormality, the oncologist may recommend a certain targeted therapy designed to attack that mutation. This form of testing may be recommended for people whose cancer stopped responding or didn’t respond well enough to conventional treatments like chemotherapy and radiation.

How they guide treatment

In both genetic and genomic testing, your oncologist may recommend treatment based on your results, such as preventive surgery in the case of genetic testing or a certain type of drug therapy in the case of genomic testing. Because most cancers develop not because of an inherited gene but because of mutations that occur throughout patients’ lifetimes, researchers are hopeful that continued advances in genomic testing will help them better target specific tumor mutations and tailor treatments to each individual.

One clinical trial that is using genomic testing to gain more insight into cancer treatments is the TAPUR study. TAPUR, or the Targeted Agent and Profiling Utilization study, is a clinical trial that aims to improve our understanding of how commercially available anti-cancer drugs perform on a broader range of cancers, by matching the drugs to tumors with specific genomic mutations that the drugs are designed to target.  

Learn about CRISPR, a breakthrough technology in genetics.