Cancer is a genetic disease caused by changes to specific genes that control the way our cells grow and divide. There are different types of cancer, each with its own genetic cause. The most prevalent types are colon, breast, and lung cancers. Genetic testing can increase awareness of certain cancer risks.The following types of genetic testing are available to help determine if patients are at a higher risk for cancer and other inherited conditions:
1. Newborn screening
Newborns are sometimes screened for genetic predispositions to various types of cancer that can be detected at birth. The most common tests for cancer look for pediatric cancer predisposition syndromes such as pleuropulmonary blastomas, precancerous lung cysts, and the BRCA2 gene for adult onset breast cancer. These tests are performed on a small number of cells taken from the blood, so they do not provide a definite diagnosis, but rather a risk profile.
2. Molecular tests
For this testing, researchers look at distinct parts of the genome. The number of chromosomes a person has is the most important factor in terms of cancer risk, along with other genes on the Y chromosome and mitochondrial DNA. This method can tell whether a patient has cancer based on the morphology (shape) and expression (level) of their genes. For example, this type of testing is particularly effective for the detection of colorectal cancers.
3. Chromosomal tests
Instead of looking at distinct parts of the genome, chromosomal tests look at specific chromosomes. This type of genetic testing compares a person’s chromosomes to a database that maps out where all the genetic material on each chromosome should be. Researchers can screen large groups of people to determine if there is an increased risk for cancer or for hereditary conditions like breast cancer.
4. Gene expression tests
For this test, researchers can measure genetic material, or RNA, from cells. This test looks for the expression of specific genes in the sample using a panel of tests, and it is often used in the detection of early-stage estrogen receptor-positive (ER+) lymph node negative breast cancer. Blood is a popular location for tissue samples to be taken, but other locations, such as tumors and even free-floating cells, are also common.
5. Germline testing
This testing looks at the genes of all the reproductive system cells. Since sperm cells are affected by cancer, germline testing could detect whether a patient has certain types of cancer, such as breast cancer and pancreatic cancer, before they develop any symptoms.
There is no one test to definitively predict cancer. However, many factors, such as family history of cancer, drive many patients to undergo genetic testing. While it may not be possible to predict cancer, family history and genetic testing can increase awareness of the risk and increase the likelihood of early diagnosis and successful cancer treatment.
