▶ Advice from an oncologist
▶ Only 5-10% of all cancers are related to genetic mutations
▶ A more comprehensive examination is possible by consulting a doctor.
I am interested in cancer-related genetic testing. Is home testing a good option? What should you know about genetic mutations and cancer? This is the advice of Professor Michael Sekeres, a cancer specialist and head of the Department of Hematology at the University of Miami’s Sylvester Comprehensive Cancer Center.
As commercial self-diagnosis tests become available directly to consumers, more people are discovering that they carry cancer risk genes. This test detects genetic mutations (variations that deviate from the norm) that are associated with specific cancers.
As an oncologist, I encourage my patients to consider several things before ordering genetic testing: First, it is relatively rare to inherit a genetic predisposition to cancer, and it is estimated that only about 5 to 10% of all cancers are related to genetic mutations.
Second, commercial tests can only detect a few genetic mutations. For example, 23andMe’s test results may indicate an increased risk of breast, ovarian, or prostate cancer. However, if you have many family members with cancer and are concerned about your risk of inheriting a cancer gene, you may want to consult with your doctor and receive a more comprehensive genetic test than this self-diagnosis test.
Lastly, think about how the test results will affect you. Doctors often do not order tests if the results do not change treatment options. We recommend that you also refer to this perspective when it comes to home testing.
If the results are negative and show that there is no cancer mutation, everyone will be relieved. But what if the result is positive? Will you implement strategies to reduce your cancer risk? Will you inform your child of the possibility of a genetic mutation? If the answer to these questions is “no,” it may be better not to have the test.
■Genetic mutation and age
Genetic mutations can also occur with age. Genes contained in the cell nucleus serve as a blueprint or manual for life activities. We inherit it from our parents, but it can change throughout our lives. These genetic mutations can cause cancer by altering the signals that tell cells to continue growing or by failing to direct damaged cells to commit self-destruction.
As we age, our cells become more likely to accumulate genetic mutations. This may be a simple coincidence, where the cell makes a mistake during self-replication, or it may be the result of exposure to toxins such as cigarette smoke or alcohol. It can take decades for cancer-causing mutations to appear. For this reason, most cancers are diagnosed in older people, and the median age of cancer diagnosis in the United States is 66 years.
A study of tens of thousands of participants without a history of cancer screened their blood for genetic mutations known to be associated with cancer, including leukemia, and found that about 10% of those in their 70s, 12% of those in their 80s, and 18% of those over 90 had these mutations. A mutation was discovered. These genetic mutations are known as CHIP (clonal hematopoiesis of indeterminate potential). We are not born with this genetic mutation, and it usually does not show up on self-tests.
However, people with the mutation were 11 times more likely to develop blood cancer in the future, and about twice as likely to develop heart disease by increasing inflammation and the development of arteriosclerosis.
Genetic mutations that cause cancer
Some of the common inherited genetic mutations that can cause cancer include:
▲BRCA1 and BRCA2: These genes are found in families where multiple family members develop cancer, including breast, ovarian, and prostate cancer. In the general population, about 1 in 400 people have one of these genes, but people of Ashkenazi Jewish descent have a higher rate, about 1 in 50.
▲MLH1, MSH2, MSH6, and PMS2: These genes can cause colon cancer, stomach cancer, ovarian cancer, and endometrial cancer, and are commonly referred to as Lynch syndrome. The chance of having this mutation is approximately 1 in 300 people in the general population.
▲TP53: This mutation can cause a variety of malignant tumors, including breast cancer, bone and soft tissue cancer, brain cancer, adrenal cancer, and leukemia, and is collectively called Li-Fraumeni syndrome. Mutation carriers can develop several cancers, with women tending to develop breast cancer first, and men tending to develop brain or soft tissue cancer first. It is estimated that up to 1 in 5,000 people inherit the TP53 mutation.
If you test positive for a genetic mutation, it is possible that the genetic mutation increases your risk of developing cancer, but the good news is that there are interventions we can take to reduce that risk. You should talk to your doctor about the plan that is best for you, including early screening and taking medications such as oral contraceptives or aspirin.
By Mikkael A. Sekeres, MD>
Questions for Dr. Michael Sekeres:
Questions for Dr. Michael Sekeres:
1. Can you provide insights on how genetic testing for cancer risk can be beneficial or detrimental to an individual’s health?
2. What factors should individuals consider before undergoing genetic testing for cancer risk?
3. How do commercial genetic testing kits differ from those conducted in medical settings?
4. Can you discuss the prevalence of genetic mutations that increase cancer risk and the age groups most affected?
5. Are there any specific genetic mutations that are more commonly associated with particular cancers?
6. What are some interventions available for individuals who test positive for genetic mutations that increase their cancer risk?
7. How does the presence of genetic mutations affect treatment options and prognosis for patients with cancer?
8. Can you elaborate on the role of genetic mutations in the development of cancer, including their origin and impact on the body’s systems?
Questions for a cancer survivor or advocate:
1. What was your experience like undergoing genetic testing for cancer risk, and how did the results impact your life?
2. How can individuals navigate the emotional challenges of learning about their genetic predisposition to cancer?
3. What, if any, are the barriers to accessing genetic testing and counseling services, and how can these be addressed?
4. What strategies have you implemented to reduce your personal cancer risk after learning about genetic mutations?
5. How can individuals help raise awareness about the importance of genetic testing and counseling in early cancer detection and prevention?
Thematic Section: Overview of Genetic Mutations and Cancer
– In this section, Dr. Michael Sekeres will discuss the importance of genetic mutations in cancer development, the frequency of these mutations in the general population, and the limited scope of commercial genetic testing kits. He will also touch upon the role of age in the accumulation of genetic mutations and the increase in cancer risk associated with certain genetic predispositions.
Thematic Section: Personal Experiences with Genetic Testing for Cancer Risk
– In this section, we will hear from a cancer survivor or advocate about their experience with genetic testing and
