Dr. Sapna Syngal has a lofty goal when it comes to genetic testing for cancer. She wants to put it on the same plane as high cholesterol and high blood pressure. “You wouldn’t refuse to get your cholesterol checked,” she reasoned. Syngal, the director of research at the Center for Cancer Genetics and Prevention at Dana-Farber Cancer Institute, explained that genetic alterations that increase cancer risk are more common than previously thought. “Ten percent of cancers can be hereditary,” she said.
Sapna Syngal, M.D., M.P.H., is the director of research, Center for Cancer Genetics and Prevention, at Dana-Farber Cancer Institute, and professor of medicine at Harvard Medical School. PHOTO: DANA-FARBER CANCER INSTITUTE
Why test?
Genes are in the DNA in each cell in the body, and function somewhat as the sheriff. They control how quickly the cell grows, how often it divides and even how long it lives. But sometimes the genes go awry. Cancers begin when one or more genes in a cell change, or mutate. This mutation can cause cells to multiply uncontrollably or stop working altogether.
Some mutations are acquired. For instance, cigarette smoke contains cancer-causing agents that can result in more than 12 types of cancer. Others are inherited, however, and run in families. Genetic testing, which is typically a blood test, looks for specific inherited mutations in a person’s genes. Several advances have been made over the years. “At one time the test looked at one to four genes commonly associated with cancer,” Syngal explained. “Now it’s often more like 30 to 50.”
Not all cases of cancer require genetic testing. There are red flags, however, which may indicate a family history of the disease:
- Diagnosis of cancer at a young age
- Different types of cancer in the same person
- Cancers that have developed in both paired organs, such as breasts or kidneys
- Several close blood relatives, such as parent, sibling or child, with the same type of cancer
- Unusual case of a specific type of cancer, such as breast cancer in a man
The purpose of testing is not only to understand one’s cancer risk but also to help develop a management plan. Some people may opt for earlier and more frequent and extensive screening. Surgery is also a viable solution. For instance, women who have a family history of Lynch syndrome, a form of hereditary colon cancer, have a 15 to 60 percent risk of uterine cancer and 1 to 38 percent risk of ovarian cancer, according
to cancer.net , an online consumer information source of the American Society of Clinical Oncology. In response as a preventive measure, a woman might opt for a total hysterectomy, which includes removal of the ovaries.
In addition, a change in lifestyle is encouraged. Tobacco use, unhealthy diet, excessive alcohol intake and lack of physical activity all increase the risk of several types of cancers whether or not they run in families.
The test results can be a little tricky to interpret. A positive test result typically indicates an increased risk of developing a particular cancer in the future. It may also reveal that a person is a carrier of the mutation, thereby increasing the risk of transference to a child.
Negative tests are not always as straight forward. A true negative, according to the National Cancer Institute (NCI), means that the laboratory did not find the specific alteration sought. However, a result called “variant of unknown significance” indicates that there is a change in a gene, but it’s unclear if it is harmless or a risk factor for cancer. The result is interpreted as ambiguous and does not provide information helpful in making health care decisions, according to the NCI.
That is why a genetic counselor or provider trained in genetics should explain the results. Not all mutations are harmful. Some may actually be beneficial, while others have no effect at all. Even inheritance of a harmful mutation does not guarantee that you will get cancer. It merely means that your risk of the disease is greater than that of the general public. Along the same vein, a negative result does not protect you from cancer. It means that your risk is average and the same as the cancer risk in the general public. Tests will tell you what “might” happen, not what “will” happen.
A personal decision
Genetic tests are now available for a number of cancers, and can estimate the risk fairly accurately. For example, the BRCA genes, which are related to breast, ovarian, prostate and pancreatic cancers, are now well known and have been studied around the world. Consequently, the known risk of cancer is estimated to be 50 to 80 percent, explained Syngal.
Experts caution against at-home or direct-to-consumer tests that may provide inaccurate or incomplete results. Testing with a certified specialist is preferable. Cost can be a factor. Although genetic testing is not a state mandated benefit, many health insurance plans in Massachusetts pay for it under certain circumstances, as does MassHealth. Plans may require prior approval, however.
Some people still shy away from the testing. They prefer to not know or suspect that the results will be shared with others. HIPAA protects a person’s privacy of health information. In addition, the Genetic Information Nondiscrimination Act, or GINA, is a federal law that protects individuals from genetic discrimination in employment and health insurance. GINA does not apply to life, disability or long-term care insurance, however, so testing is often recommended after receipt of such insurance.
Syngal cautions against not knowing. It’s not like Alzheimer’s disease, she explained, for which there is no known prevention or cure. “Understand that testing can help prevent cancer,” she explained. “Avoiding it is a missed opportunity.”
She sums up her message in a few words “Know your family history,” she emphasized. “Then get tested.”
AT A GLANCE
Types of cancers commonly associated with gene mutations:
- Breast
- Ovarian/fallopian tube
- Pancreatic
- Prostate
- Melanoma
- Uterine
- Colon
- Gastric (stomach)
Source: FORCE (Facing Our Risk of Cancer Empowered) https://www.facingourrisk.org/index.php
