Testing Panel Familial Cancer (CGx) Panel:
This panel identifies the risk of genetic factors for various cancers such as breast cancer, ovarian cancer, colon cancer, colon polyps, prostate cancer, melanoma, and others that run in a family. The test looks for inherited genetic variations (germline mutations) associated with an increased risk of cancer. With knowledge of genetic risk factors, physicians would be able to personalize patient healthcare plans. Conversely, sporadic cases of breast cancer happen in patients that do not carry any mutation.
What We Offer:
The Comprehensive Cancer Testing panel is an assessment of 120 genes associated with increased risk for a variety of hereditary cancers. These associations have been assessed by the scientific community and all relevant research is included on reports. Using Next Generation Sequencing technology, variations in the genetic code can be detected from non-invasive buccal swabs. These variations are assessed for known associated risks that may allow for preventative precautions or give insight for future treatment. The report is comprehensive and easy for your doctor to interpret, allowing for them to provide the best treatment plan possible moving forward.
Definition of cancer risk factor:
Familial cancer genetic tests provide lifetime risk of cancer development. They cannot state if a patient will develop cancer for sure. But they can determine whether an individual has a higher risk than most people. Only some people with a gene mutation will develop cancer. Nathanson et al. (2001) reported lifetime breast cancer risk of 60 to 80{788689b1f96e6e5a29b7ebdc0a74f574bcea9748ac8e484e1c92285099e82813} for female BRCA1 mutation carriers, although lifetime risk estimates as low as 36{788689b1f96e6e5a29b7ebdc0a74f574bcea9748ac8e484e1c92285099e82813} had been reported in other studies.
Method:
CGx genetic test investigates a panel of genes (listed below) for the presence of genetic changes compared to human reference (variants) that are linked to increased lifetime risk of cancers. Express Gene Comprehensive Familial Cancer (Cancer) Panel is a Laboratory Developed Test (LDT) validated at Express Gene Molecular Diagnostics Laboratory, using Twist Exome 2.0 and Illumina NovaSeq6000 Next Generation Sequencing (NGS) Platform. This test has not been cleared or approved by the FDA.
Limitations of Testing:
This test is designed to detect individuals with a germline pathogenic variant. Repeat expansion disease, large deletion, duplication and copy number variations, are not detectable by next generation sequencing (NGS) and require different test methodologies. Mutations in the upstream and downstream regulatory regions and mutations outside exons of protein-coding genes are not investigated. Certain types of variants, such as structural rearrangements, inversions, translocations, variants in regions with low complexity, regions with complex architecture, short tandem repeats, or segmental duplications cannot be detected by this method. Additionally, low level mosaicism, phasing, regions with matching pseudogenes causing mapping ambiguity cause incorrect or insufficient variant calling. The CGx test should not be ordered on tumor tissue.
Genetic counseling:
Genetic counseling is recommended to explain the results, risks, and potential pitfalls of the CGx cancer testing panel. Genetic testing can have potential emotional and social harms. Psychological stress can arise from learning that one has a genetic variant that increases cancer risk, as well as from making decisions regarding whether to share test findings with blood relatives. Survivor’s guilt can also occur upon learning that one does not have a harmful variant present in other family members.
Purpose of the CGx test:
Genes are instructions, written in DNA, for building protein molecules. Different people can have different versions of the same gene. Each version has a slightly different DNA sequence. Some of these variants affect health, such as those gene variants linked to increased risk of cancers. These cancer-related variants can run in families. Several genes involved in many known inherited cancers have been identified. Testing whether someone carries a harmful (pathogenic) variant in one of these genes can confirm whether a condition is, indeed, the result of an inherited syndrome. Genetic testing is also done to determine whether family members who have not (yet) developed a cancer have inherited the same variant as a family member who is known to carry a harmful (predisposing cancer susceptibility) variant. More than 50 hereditary cancer syndromes have been described. Most of these are caused by harmful variants that are inherited in an autosomal dominant fashion—that is, a single altered copy of the gene inherited from one parent is enough to increase a person’s chance of developing cancer.
How Will I Benefit?
In order to treat cancer, it must be identified. The origin site and mode of cancer need to be known as well, otherwise the battle is a shot in the dark. Certain genetic variants have been associated with increased risks for specific cancers and can be valuable information in preventing and treating cancer. Early diagnosis is a key factor in the success of cancer treatment. Patients identified with hereditary cancer susceptibility can benefit from increased surveillance and preventative steps to better manage their risk for cancer. Knowing the specific gene involved can guide medical management and avoid unnecessary follow up. Information obtained from candidate gene testing may be helpful in guiding clinical management in the future. If a pathogenic variant is identified in your patient, close relatives (children, siblings, parents) could have as high as a 50{788689b1f96e6e5a29b7ebdc0a74f574bcea9748ac8e484e1c92285099e82813} risk to also be at increased risk. In some cases, screening should begin in childhood.
What is the outcome of familial cancer test results:
A. Positive Result.
A positive test result indicates a variant linked to cancer has been identified. This knowledge provides the patient and health care provider an opportunity to understand and, in some cases, manage their cancer risks. For people who are already diagnosed with a cancer, results of genetic testing may help them make decisions about their treatment and understand their risk for other cancers. Genetic testing provides an opportunity for family members to learn about their own cancer risks.
B. Variation of uncertain significance (VUS).
If genetic testing shows a change that has not been previously associated with cancer, the person’s test result may report a 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. Some gene variants may be reclassified as researchers learn more about variants linked to cancer. Most often, variants that were initially classified as variants of uncertain significance are reclassified as being benign (not clinically important), but sometimes a VUS may eventually be found to be associated with increased risks for cancer. Therefore, it is important for the person who is tested to keep in touch with the health care provider to ensure that they receive updates if any new information on the variant is learned.
C. Negative Result.
A negative test result means that the laboratory did not find the genetic variants that are known to be associated with an increased risk for the cancers tested. However, this does not eliminate the possibility of cancer, especially if the cancer is due to a genetic variant not included in the panel or if it’s due to non-genetic factors.