Genetic Testing for Cancer

What is genetic testing?

Genetic testing is the use of medical tests to look for changes(mutations) in a person’s genes.  The changes in genes or mutations play an important role in the development of cancer.  They can cause cells to grow out of control which can lead to cancer.  According to National Cancer Institute, inherited mutations are thought to play a role in about 5 to 10 percent of all cancers.  

What genetic tests are available for cancer risk?

More than 50 hereditary cancer syndromes have been identified. The list below includes some of the more common inherited cancer syndromes for which genetic testing is available. Hereditary breast cancer and ovarian cancer syndrome Genes: BRCA1, BRCA2 Related cancer types: Female breast, ovarian, and other cancers, including prostate, pancreatic, and male breast cancer Li-Fraumeni syndrome Gene: TP53 Related cancer types: Breast cancer, soft tissue sarcoma, osteosarcoma (bone cancer), leukemia, brain tumors, adrenocortical carcinoma (cancer of the adrenal glands), and other cancers Cowden synd rome (PTEN hamartoma tumor syndrome) Gene: PTEN Related cancer types: Breast, thyroid, endometrial (uterine lining), and other cancers Lynch syndrome (hereditary nonpolyposis colorectal cancer) Genes: MSH2, MLH1, MSH6, PMS2, EPCAM Related cancer types: Colorectal, endometrial, ovarian, renal pelvis, pancreatic, small intestine, liver and biliary tract, stomach, brain, and breast cancers Familial adenomatous polyposis Gene: APC Related cancer types: Colorectal cancer, multiple non-malignant colon polyps, and both non-cancerous (benign) and cancerous tumors in the small intestine, brain, stomach, bone, skin, and other tissues   Retinoblastoma Gene: RB1 Related cancer types: Eye cancer (cancer of the retina), pinealoma (cancer of the pineal gland), osteosarcoma, melanoma, and soft tissue sarcoma Multiple endocrine neoplasia type 1 (Wermer syndrome) Gene: MEN1 Related cancer types: Pancreatic endocrine tumors and (usually benign) parathyroid and pituitary gland tumors Multiple endocrine neoplasia type 2 Gene: RET Related cancer types: Medullary thyroid cancer and pheochromocytoma (benign adrenal gland tumor) Von Hippel-Lindau syndrome Gene: VHL Related cancer types: Kidney cancer and multiple noncancerous tumors, including pheochromocytoma  

How is genetic testing done?

Genetic tests are usually requested by a person’s doctor or other health care provider.  The testing is usually done on a small blood sample.  The sample is then sent to a genetic testing laboratory.  The test results normally take several weeks.  

What are the reasons to consider genetic testing for cancer?

Genetic testing is a personal decision made for various reasons. And it’s a complex decision best made in collaboration. Engage your family, doctor, and genetic counselor in the process. ASCO recommends considering genetic testing in the following situations: 1. A personal or family history suggests a genetic cause of cancer. 2. A test will clearly show a specific genetic change. 3. The results will help with diagnosis or management of a condition. For example, you may take steps to lower your risk. Steps may include surgery, medication, frequent screening, or lifestyle changes.   Resources https://www.cancer.net/navigating-cancer-care/cancer-basics/genetics/genetic-testing-cancer-risk https://www.cancer.org/cancer/cancer-causes/genetics/understanding-genetic-testing-for-cancer.html https://www.cancer.gov/about-cancer/causes-prevention/genetics/genetic-testing-fact-sheet