Cancer Treatment: DNA Damage Repair
Damage Repair and Cancer Treatment
Certain genes are important for repairing damage. These genes are sometimes referred to as " damage repair" (DDR) genes. Our animated video below explains how mutations can lead to cancer.
- In a normal cell, a mutation in a DDR gene increase the chance that it will become cancer. This is why an in a gene that repairs damage increases the risk for cancer.
- In a cancer cell, a mutation in a DDR gene can keep it from repairing damage caused by treatment. This means that cancer cells with mutations in these genes may be more sensitive to certain treatments.
Two main types of damage repair genes are linked to increased cancer risk and improved response to certain types of treatment:
Genetic tests can identify people with an in a DDR gene. tests can find tumor cells that have difficulty repairing these types of damage.
HRR and HRD-positive
HRR ( Response) genes repair a type of damage known as "double-stranded damage." Cancers with difficulty repairing this type of damage are known as ( deficient). Cancers that have difficulty repairing this type of damage may respond better to treatment with a type of known as PARP inhibitors.
- Genetic testing for inherited () mutations may help identify people who would benefit from treatment with a . This includes people with advanced breast, ovarian, pancreatic or cancer.
- Tumor testing for acquired (somatic) mutations may help identify people who would benefit from treatment with a . This includes people with advanced ovarian or cancer.
- testing is a special type of test to find tumors that have difficulty repairing double-stranded damage. testing looks for "genomic instability" within tumors, that makes it hard for them to repair damage. Tumors that have this type of genomic instability are sometimes called "HRD-positive." testing can help find ovarian cancers that respond better to PARP inhibitors. testing may also be used to find people who qualify for certain clinical trials.
- HRR testing is a special type of to find tumors that have certain mutations that may make them sensitive to PARP inhibitors. HRR testing can help find cancers that respond better to PARP inhibitors. HRR testing may also be used to find people who qualify for certain clinical trials. HRR testing looks for tumor mutations in the following genes:
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MSI-H and ()
"Mismatch repair" (MMR) genes repair damage that occurs during cell division. Tumors with mutations in mismatch repair genes are called "mismatch repair deficient" (also called or ). These tumors typically have an abnormality known as High or . Mutations in the genes are often associated with tumors:
Testing tumors for dMMR/MMR-D or can be important, because these tumors are more likely to respond to a type of known as immune checkpoint inhibitors.
tests for tumor mutations and genetic tests for inherited mutations
Some tumor tests look for gene mutations in cancer cells. These tests differ from genetic tests for inherited cancer risk.
As cells become cancerous, they develop many gene mutations that cause abnormal growth. These gene changes, which occur after you are born and throughout your life—are known as acquired or "somatic" mutations. Acquired mutations are different than inherited mutations, which are passed on from parent to child and are present at birth in every cell.
Tumor tests can look for mutations in cancer cells. Genetic tests for inherited mutations look at normal cells in blood or saliva to find gene changes that are present from birth, passed from parents to children and are linked to increased risk for .
Information provided by tumor testing and genetic testing may overlap. When someone with an develops cancer, their cancer cells will likely carry the same mutation. For example, a person born with a mutation will have that mutation in all of their cells. If they develop cancer, their cancer cells will likely also have the same mutation. If a person born with an inherited mutation develops colorectal cancer, their cancer cells will have the same mutation and will likely also be .
Not all tumor tests can distinguish inherited mutations from acquired mutations. If your shows a mutation, ask your doctor if it may be hereditary and if you should have genetic testing for an .
