Genetic Testing vs. Genomic Testing
We all know that our DNA can be very useful in figuring out what part of the world our ancestors hail from, but can understanding our DNA really help in the treatment of cancer? For more and more of us the answer is yes. Thanks to the advances in genetic and genomic testing, doctors are able to offer targeted therapies based on the results of these tests. But what the difference between genetics and genomics?
- Genetics is the study of heredity (genes that you inherited from your parents)
- Genomics is the study of genes and their functions
Genetic testing detects hereditary alterations in DNA, while genomic testing detects acquired (over the course of a lifetime) alterations in DNA.
Some of the common mutations we’ve heard about, like BRCA1 and BRCA2 are examples of genetic mutations (germline mutations). These genetic mutations are passed on from parent to child, and increase an individual’s chance of developing certain types of cancers. For example, if you have a BRCA1 mutation, you have a higher risk of developing, breast, ovarian, pancreatic, and prostate cancer.
In addition to genetic testing, there are now genomic tests that can look at certain tumors and identify which therapies might work better against those tumors. These are called targeted therapies. For example, there is now a genomic test that can look at the tissue of an ovarian tumor to detect BRCA mutation types that may benefit from a targeted therapy called a PARP inhibitor.
All genetic or genomic testing is done by analyzing a biopsy. Traditionally this has meant a tissue biopsy. Unfortunately, not all tumors are easy or comfortable to access for a biopsy. Often tissue biopsies mean invasive procedures like surgery, which isn’t always an option because of poor health or the location of the tumor. Thankfully there is a new hope: Liquid Biopsies.
What are Liquid Biopsies?
Liquid biopsies are blood tests that are analyzed to assess mutations and other changes in a tumor’s DNA. This is possible, because tumors continually shed dead cells into the blood stream.
On June 1, 2016, the FDA approved the first liquid biopsy test for use in cancer treatment. The test detects key mutations in the EGFR gene that makes patients with advanced non-small cell lung cancer candidates for a specific treatment option. Previously, tumor specimens were used to detect these mutations.
At this point, these tests may be most valuable to patients with advanced stage cancer. They can be used to monitor changes over time and direct treatments when tumors recur or progress. Eventually, liquid biopsies may be able to help direct care for patients with earlier-stage cancer or help monitor disease progression in people with precancerous lesions. Scientists caution that more research is needed before liquid biopsies are used routinely in cancer care, but this is an area of intense study, so the future looks bright. The scientific advances in genetic and genomic testing as well as liquid biopsies are allowing cancer patients to benefit from this new era of precision medicine.
For more information about genetics and genomics, watch our webinar recording.