Genetic Testing Can Identify Chance Of Breast, Ovarian Cancers
2018 Nov, 01 | Source: doverpost.com
Modern technology is providing hope for women with a genetic disposition toward cancer
Researchers have been digging deep into some of the most basic elements of human physiology to push back against an age-old killer.
Genetic testing, which became available for clinical use about 20 years ago, promises hope for women who may have an increased chance of developing certain cancers.
Progress in the field has been rapid; patients now can get results in less time than two decades ago and researchers can perform more tests on the same sample for about the same cost as before.
Unlike some diseases that occur when an outside factor, such as a virus, attacks the body, cancers develop when the body’s normal routine of replacing dying or damaged cells goes out of whack, causing uncontrolled change and growth. These mutated cells form tumors which can spread to other parts of the body, crowding out healthy cells.
By taking a sample of a woman’s blood, scientists now can look into her DNA for changes in two specific genes, BRCA1 and BRCA2, that normally help avert breast and ovarian cancers.
All human beings have these cancer-preventing genes in their DNA, genes that normally repair damaged DNA and suppress tumors. If a BRCA gene itself is damaged and cannot perform properly, it cannot prevent the uncontrolled cell growth that puts an individual at a greater risk of developing breast cancer.
“Both BRCA1 and BRCA2 are important in correcting DNA damage from outside factors,” Kendra Flores, a genetic counselor at Christiana Health Care System’s Helen F. Graham Cancer Center and Research Institute said. “If these genes are not functioning correctly the body is more susceptible to environmental DNA damage and tumor formation.”
Research has shown both men and women are prone to these BRCA mutations and can pass these altered genes to their children, Flores said.
Having mutated BRCA1 or BRCA2 genes does not always mean an individual will develop breast or ovarian cancer, she said, but finding these altered genes can lead to increased monitoring that will help detect any cancer sooner.
Oncologists have long agreed that the sooner a cancer is found, the greater chance of survival, and often recommend genetic testing if a woman’s family history indicates she may carry mutated BRCA genes.
Genetics plays a part in the development of between five and 10 percent of cancers, including breast and ovarian cancers, Flores said.
According to a 2016 article in the journal Oncology, breast cancer remains the second leading cause of cancer-related deaths in the United States. Ovarian cancer, while less common, has a higher mortality rate than breast cancer, primarily because it is not discovered until its latter stages when treatment options are more limited.
While just five to 15 percent of breast or ovarian cancers usually are related to known hereditary causes, that can jump to 20 to 40 percent for people with a family history of these cancers.
The BRCA test is not routine and is not suggested for women who have only an average cancer risk.
In Delaware, when a woman’s doctor believes such a test is appropriate, they usually are referred to the Graham Center for counseling.
There, patients discuss their personal medical history, including any cancer histories and their cancer screening regimen, Flores said. This includes a discussion about family medical history, including what cancers have been seen and how old individuals were when diagnosed.
“Then the genetic counselor and patient have a conversation about the nature of genetic testing, including the risk, benefits, and limitations of current offerings,” she said. “The goal of this conversation is to empower patients to decide whether testing is right for them.”
If the patient agrees, blood is drawn at a lab in the Graham Center and, in some cases, saliva samples are taken.
The samples are sent to a laboratory for a DNA analysis and findings returned to the genetic counselor, who then sits down with the patient to discuss the results.
Automation has helped speed up the testing, Flores said.
“In the beginning, the laboratory technician had to do all the test sequencing by hand,” she said. Now each step is controlled by a computer, meaning what once took up to 45 days now can be done in about two weeks.
“By running genes through a computer, they’re able to do more tests for many more cancer genes at about the same cost,” Flores said. “And it means that the number of people expressing an interest in genetic testing has skyrocketed.”
While patients found with a mutation in one of the BRCA genes won’t necessarily develop breast or ovarian cancer, they have a higher risk, Flores said.
That risk varies widely and can reach as high as 87 percent, she said.
“During a genetic counseling session, we would discuss the cancers currently associated with the positive gene, and the risk numbers for each cancer, if they are known,” she said.
“We then discuss the different options available for follow up. In some cases that means increased or early screening, such as colonoscopies sooner or more frequently.”
Flores said the counselor may recommend follow-up measures which could include increased screening for breast cancer, medications to decrease the risk of cancer or preventive surgery to remove healthy breast tissue.
“Some women choose to employ a proactive approach by reducing their risk through these surgeries,” Flores said. “Others pursue an increased frequency screening, such as utilizing both mammograms and breast MRI. As a genetic counselor, I review the pros and cons of each option and encourage followup with treating physicians.”
Sometimes the test will be inconclusive, meaning a mutation was discovered but it’s not possible to tell if it could be associated with an increased cancer risk.
A negative test will show the patient does not carry any mutated BRCA genes. That person still is at a normal risk for developing cancer based on other factors.
“Genetic testing has significant limitations,” Flores said. “In the vast majority of cases, genetic testing cannot eliminate a family history of cancer.
“Family history remains one of the best indicators of cancer risk, therefore even in cases of negative genetic testing results, genetic counselors often discuss tailored screening regimens based on a person’s family history of cancer.”
Testing generally is covered by medical insurance plans.
According to the National Cancer Institute, Medicare will pay for testing for women who have symptoms and signs of breast, ovarian or other cancers related to mutations in these genes.
Some genetic testing companies may offer free testing for people who have no health insurance and who meet certain financial guidelines and medical criteria.