The Importance of Genetic Testing in Cancer Research

It’s common for cancer patients and their families to feel helpless, as if their futures and those of their loved ones are entirely dependent on physicians and medications. Genetic testing is one way for cancer patients and their relatives to regain a sense of control over the horrible disease, and make a valuable contribution toward improving cancer detection, new cancer treatments and understanding cancer prevention methods.

One of the most effective ways for cancer researchers to learn why a type of cancer occurs (an important step in discovering new cancer treatments) is to study the genes of cancer patients and those who share their DNA profile.

How is Genetic Testing used to Advance Cancer Research?

When researchers study the genes from a large sampling of individuals who have or are susceptible to certain cancers, they’re able to detect patterns, or genetic markers. This information can be used to predict the likelihood that someone will develop a disease, as well as to develop cancer screening tests, prevention protocols and various cancers treatments.

Because of cancer genetic testing, researchers from the National Cancer Institute’s Division of Cancer Epidemiology & Genetics (DCEG) have made important discoveries that have advanced cancer research and cancer treatment. For example:

  • Researchers studying the genes of a patient with nevoid basal-cell carcinoma syndrome identified the gene responsible for the skin cancer. That finding culminated in the first U.S. Food & Drug Administration-approved biological agent therapy for advanced and metastatic basal cell skin cancer.
  • Researchers studying breast cancer patients’ genes discovered that a gene mutation on the BRCA1 or BRCA2 gene increases the likelihood of developing the disease. Today, people who discover they have this gene have the option of choosing elective mastectomies to reduce their risks of breast cancer.
  • Researchers studying the genes of dyskeratosis congenita patients discovered that 60 percent have the same genetic mutation. That finding led to a new diagnostic test for the disease and new criteria for evaluating potential bone-marrow donors.
  • Researchers studying monoclonal B-cell lymphomatosis patients discovered that the disease is a precursor for chronic lymphocytic leukemia (CLL). That finding paved the way for screening tests now used to diagnosis CLL in its early stages, which allows patients to begin treatment before the disease advances.

The research continues. DCEG researchers are currently conducting several studies, including:

  • Studies of melanoma-prone families to search for “melanoma susceptibility” genes.
  • Studies of patients with a group of rare genetic blood disorders known as inherited bone marrow failure syndromes to learn how these cancers develop.
  • Studies of children with a rare lung tumor, pleuropulmonary blastoma, to determine if changes in a particular gene contribute to this lung cancer.

Genetic testing isn’t foolproof, but it is a powerful tool for cancer patients who want to contribute to science, and individuals who want to assess their risks.

How Is Genetic Testing Conducted?

Most physicians require a patient to undergo genetic counseling before undergoing genetic testing for cancer because the results of your cancer genetic test may yield unwelcome news, and patients should be prepared.

In most cases, the process of undergoing genetic testing is surprisingly simple and painless. Typically, the person being tested provides either:

  • A blood sample (usually several tubes taken from a vein in your arm)
  • A sample of DNA obtained from saliva, skin cells or cheek cells (obtained by swabbing the inside of the cheek)
  • Genetic testing for a fetus may require the mother to have an amniocentesis, although non-invasive prenatal tests are also available

The sample is sent to a genetic testing laboratory for analysis, where they will determine your sample to be positive, negative or inconclusive. Within two – three weeks, the detailed results will be sent to the physician of genetic counselor who ordered the testing.

Can anyone be Candidate for Cancer Research Genetic Testing?

Genetic testing leads to genetic screening tests. Individuals with family histories of certain types of cancer (such as breast cancer, ovarian cancer, colon cancer, and others) who are interested in learning if they possess a certain hereditary gene mutation — and who are mentally prepared for the possibility of a positive result — are candidates for genetic testing.

Features suggestive of hereditary cancers include:

  • Any individual diagnosed with cancer prior to age 50
  • Any individual who has developed more than one cancer
  • Any individual with a rare type of cancer (ovarian, male breast cancer, pancreatic)
  • An individual with two or more family members diagnosed with the same cancer
  • A family member with an identifiable gene mutation known to increase the risk of cancer
  • Ashkenazi Jewish ancestry with a personal or family history of  cancer

Individuals who already have cancer and want to contribute to research that could lead to advances in detection and treatments are also candidates.

If you or someone in your family thinks they need to have cancer genetic testing performed, it is important to review our Genetic Risk Assessment section with your doctor or genetic counselor, or if you are located in the Maryland or Washington DC area, schedule an appointment with the Maryland Oncology Hematology team for a more in depth discussion.

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