Understand the limitations of genetic testing and how it helps
Understand the limitations of genetic testing and how it helps
You can take several steps to help reduce your risk of developing cancer. Quit smoking. Reduce alcohol consumption. Use sunscreen. These and other lifestyle changes can significantly reduce your risk of developing cancer. But when it comes to managing the cancer risks you’re born with, those risks that may be lurking in your genetic profile, requires more strategy than changing your diet or daily habits. It often begins with the acquisition of new knowledge, by determining whether certain genetic mutations have been passed on to you, with the help of a blood test.
Genetic testing looks for mutations in certain genes that may indicate an increased risk of cancer. “A patient can use this information to increase screening tests that can help detect cancer early,” says Melanie Korpman, a licensed and certified genetic counselor at our Hospital in Philadelphia. “And there may be an option for preventive surgery to reduce the risk of cancer.” In the most notable example, actress Angelina Jolie opted to undergo a preventive double mastectomy in 2013 after learning she carried a mutated BRCA1 gene that increased her risk of breast, ovarian or other cancers. Jolie’s mother died at 56 from ovarian cancer. Two years later, Jolie underwent another preventative procedure to remove her ovaries and fallopian tubes.
But as useful as genetic testing can be, it’s important to understand that it has limitations in measuring cancer risk. For example, they cannot predict with certainty whether you will develop cancer, and they cannot determine which cancer you are more likely to develop. Identifying the genetic mutation can only mean that you have an increased risk of cancer, and risks can include several types of cancer. Not all cancers are linked to genetic mutations. In fact, inherited genetic defects have been linked to only 5 to 10 percent of all cancers, according to the National Cancer Institute.
However, genetic testing can be useful in measuring the risk of some common and major cancers, including breast, colorectal, pancreatic, ovarian, prostate, thyroid and uterine cancers. Tests usually identify inherited cancer syndromes, which are characterized by defective genes that are passed on from generation to generation.
Common syndromes
Some of the more common syndromes include:
| Syndrome | genes | Associated cancers |
|---|---|---|
| Hereditary breast cancer and ovarian cancer syndrome | BRCA1 ، BRCA2 | ………………………. |
| Li-Fraumeni syndrome | TP53 | Breast, soft tissue and bone sarcoma, leukemia, brain and adrenal cortical carcinoma |
| Cowden syndrome | PTEN | Breast, thyroid and endometrium |
| Lynch syndrome | MSH2 ، MLH1 ، MSH6 ، PMS2 ، EPCAM | Intestine, endometrium, ovary, renal pelvis, pancreas, liver, stomach, brain, breast |
| familial adenomatous polyposis | APC | Malignant and benign tumors of the intestine, brain, stomach, bone and skin |
| retinoblastoma | RB1 | Eye (retina), melanoma and soft tissue sarcoma |
| Multiple endocrine neoplasia type 2 | retired و | Thyroid gland (medulla), benign tumors of the adrenal gland |
| von Hippel-Lindau syndrome | VHL | Kidney, multiple non-cancerous tumors |
| Source: National Cancer Institute |
Genetic testing is not for everyone. “There are some red flags about who should get genetic testing,” Korpman says. You may also consider genetic testing if:
- You were diagnosed with cancer when you were young or when you were younger than the guidelines for certain cancers, such as breast cancer or colon cancer under the age of 50.
- Cancer is found in both organs in a group of two, such as the breast or kidney (commonly known as bilateral cancer).
- You have a strong family history of cancer, such as having multiple relatives on one side of your family who have been diagnosed with the same type of cancer.
- There is more than one type of cancer in your family.
- Another family member with a known genetic mutation.
- Family members were diagnosed with cancer at an early age.
- Being of a certain ethnicity, such as African American or Ashkenazi Jewish, and you may be at increased risk of mutations in genes associated with cancer risk.
A genetic counselor can help determine if genetic testing would be helpful and is usually the professional who helps interpret the test results. If you choose to have genetic testing, Korbman recommends preparing for the wave of emotions you may experience after you get the results. “A positive result can make you feel anxious or guilty,” says Korbman. “Sometimes the hardest thing to accept is that he may have passed that on to his children.”
