CGx – Genetic Cancer

CGx Testing Services

CGx testing is a preventative gene test that looks for specific inherited changes (mutations) in a person’s genetic make-up. Harmful mutations may increase a persons’ chance, or risk, of developing a disease such as cancer. These conditions are considered hereditary. Appropriate genetic testing may be used to determine an individual’s risk and potential treatment options as indicated. Genetic mutations can have harmful, beneficial, neutral (no effect), or uncertain effects on health. Harmful mutations may increase a person’s chance, or risk, of developing a disease such as cancer. Overall, inherited mutations are thought to play a role in about 5 to 10 percent of all cancers.

Which patients qualify for testing?

  • Patients with several first-degree relatives (mother, father, sisters, brothers, children) with cancer or a history of cancer.
  • Patients that have many relatives on one side of the family who have had the same type of cancer.
  • Patients that have a family member with more than one type of cancer (like a woman with breast and ovarian).
  • Patients that have family members who had cancer at a younger age than normal for that type of cancer (Like colon cancer in a 20-year-old female).
  • Patients with an ethnicity (for example, Ashkenazi Jewish ancestry) that is linked to ovarian and breast cancers.
  • Patients that have a cluster of cancers in your family that are known to be linked to a single gene mutation (such as breast, ovarian, and pancreatic cancers in your family).
  • Patients that have had cancer in the past.
  • Patients with family members that have cancers occurring in both of a pair of organs (like both eyes, both kidneys, or both breasts).
  • Patients that have family members with more than one childhood cancer in siblings (like sarcoma in both a brother and a sister).
  • Patients that have family members that have cancer occurring in the sex that is usually not affected (like breast cancer in a man).
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What is genetic cancer caused by?

Cancer is usually caused by gene mutations that occur randomly in one or a few cells of the body. Such gene changes, called somatic mutations, may arise as a natural consequence of aging or when a cell’s DNA has been damaged. Acquired mutations are only present in some of the body’s cells, and they are not passed on from parents to their children. However, in a small percentage of people with cancer, the disease is due to a different type of mutation called a hereditary mutation, or germline mutation. These mutations are usually inherited from one or both person’s parents. Because hereditary mutations are present in the DNA of sperm and egg cells, they can be passed down in families. People who carry such hereditary mutations do not necessarily get cancer, but their risk of developing the disease at some point during their lifetime is higher than average. In recent years, scientists have discovered several mutations that can contribute to a person’s risk of developing certain cancers.

What is genetic cancer caused by?

Cancer is usually caused by gene mutations that occur randomly in one or a few cells of the body. Such gene changes, called somatic mutations, may arise as a natural consequence of aging or when a cell’s DNA has been damaged. Acquired mutations are only present in some of the body’s cells, and they are not passed on from parents to their children. However, in a small percentage of people with cancer, the disease is due to a different type of mutation called a hereditary mutation, or germline mutation. These mutations are usually inherited from one or both person’s parents. Because hereditary mutations are present in the DNA of sperm and egg cells, they can be passed down in families. People who carry such hereditary mutations do not necessarily get cancer, but their risk of developing the disease at some point during their lifetime is higher than average. In recent years, scientists have discovered several mutations that can contribute to a person’s risk of developing certain cancers.

Most Common Types of Hereditary Cancers

  • Prostate Cancer
  • Ovarian Cancer
  • Breast Cancer – Male and Female
  • Uterus Cancer
  • Colorectal Cancer
  • Thyroid Cancer
  • Leukemias and Lymphomas
  • Heriditary Neuroendoctrine Tumor Disorders
  • Endometrial Cancer
  • Pancreatic Cancer

Personal History of Cancer that Qualify for Testing

  • Prostate Cancer
  • Ovarian Cancer
  • Breast Cancer – Male and Female
  • Uterus Cancer
  • Colorectal Cancer
  • Thyroid Cancer
  • Leukemias and Lymphomas
  • Heriditary Neuroendoctrine Tumor Disorders
  • Endometrial Cancer
  • Pancreatic Cancer
  • Uveal Melanoma – Specific Panel
  • Melanoma
  • Non – Small Cell Lung Cancer
  • Gastrointestinal Stromal Tumor
  • Cancer of Unknown Primary (CUP)  Desmoid Fibromatosis
  • Hepatic Adenoma
  • Urinary Tract
  • Bladder

What is the role of genetic counseling in genetic testing for a hereditary cancer syndrome?

What is the role of genetic counseling in genetic testing for a hereditary cancer syndrome?

Genetic counseling is generally recommended before any genetic testing for a hereditary cancer syndrome and may also be performed after the test, especially if a positive result is found and a person needs to learn more about the hereditary cancer predisposition syndrome they have been found to have. This counseling should be performed by a trained genetic counselor or other health care professional who is experienced in cancer genetics. Genetic counseling usually covers many aspects of the testing process, including:

  • A hereditary cancer risk assessment which is based on an individual’s personal and family medical history.
  • The appropriateness of genetic testing and potential harms and benefits of testing.
  • The medical implications of positive, negative, and uncertain test results.
  • The possibility that a test result might not be informative (that is, it might find a variant whose effect on cancer risk is not known).
  • The psychological risks and benefits of genetic test results.
  • The risk of passing a variant to children.
  • The impact of testing for the family.
  • Suggestions for the best test to perform.

What can you expect for results from CGx testing?

This test will not tell you if you have cancer today or that you will get cancer in the future. The CGx test will help determine your risk of developing cancer. One of the greatest benefits of the test is determining if you have a genetic precursor or genes that may pass an increased cancer risk to your children.

What do the results of genetic testing mean?

Genetic testing can give several possible results: positive, negative, true negative, uninformative negative, variant of uncertain significance, or benign (harmless) variant.

Positive result. A positive test result means that the laboratory found a genetic variant that is associated with an inherited cancer susceptibility syndrome. A positive result may:

  • For a person who has cancer, confirm that the cancer was likely due to an inherited genetic variant and help guide treatment choices.
  • Indicate an increased risk of developing certain cancer(s) in the future and guide future management to lower that risk.
  • Provide important information that can help other family members make decisions about their own health care, such as whether to have genetic testing to see if they have also inherited the variant.

Also, people who have a positive test result that indicates that they have an increased risk of developing cancer in the future may be able to take steps to lower their risk of developing cancer or to find cancer earlier, including:

  • Being checked at a younger age or more often for signs of cancer.
  • Reducing their cancer risk by taking medications or having surgery to remove “at-risk” tissue.
  • Changing personal behaviors (like quitting smoking, getting more exercise, and eating a healthier diet) to reduce the risk of certain cancers.
  • Getting help to guide decisions about fertility and pregnancy. 

Negative result. A negative test result means that the laboratory did not find the specific variant that the test was designed to detect. This result is most useful when a specific disease-causing variant is known to be present in a family. In such a case, a negative result can show that the tested family member has not inherited the variant that is present in their family and that this person, therefore, does not have the inherited cancer susceptibility syndrome tested for. Such a test result is called a true negative. A true negative result does not mean that there is no cancer risk, but rather that the risk is probably the same as the cancer risk in the general population.

When a person has a strong family history of cancer but the family has not been found to have a known variant associated with a hereditary cancer syndrome, a negative test result is classified as an uninformative negative (that is, it typically does not provide useful information).

In the case of a negative test result, it is important that the person’s doctors and genetic counselors ensure that that person is receiving appropriate cancer screening based on that person’s personal and family history and any other risk factors they may have. Even when genetic testing is negative, some individuals may still benefit from increased cancer surveillance.

Variant of uncertain significance. If genetic testing shows a change that has not been previously associated with cancer, the person’s test result may report a variant of uncertain significance or VUS. This result may be interpreted as uncertain, which is to say that the information does not help to clarify their risk and is typically not considered in making health care decisions.

Benign variant. If the test reveals a genetic change that is common in the general population among people without cancer, the change is called a benign variant. Everyone has commonly occurring benign variants that are not associated with an increased risk of disease.

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