Novel Procedure Considered an ‘Acceptable Method’ to Preventing Transmission of Hereditary Cancer Mutations to Children
People who are at greater risk of developing a hereditary cancer, or who have previously been diagnosed with hereditary cancer, have an “acceptable method” at their disposal to determine the chances of those — and other — genetic mutations. pass it on to their future children.
The procedure, known as preimplantation genetic testing, helps identify any genetic abnormalities in embryos created during the process of in vitro fertilization (IVF).
This procedure can effectively help people with a previous diagnosis or risk of hereditary cancer pass those genetic mutations on to future offspring.
At the recent 12th Annual Joining FORCES Against Hereditary Cancer conference, Dr. Terri L. Woodard, an associate professor in the Department of Gynecological Oncology and Reproductive Medicine at the University of Texas MD Anderson Cancer Center at Houston, addresses the topic of fertility preservation and parenting issues often faced by survivors and previous cancer patients. In addition, Woodard emphasized what people need to know about certain genetic testing procedures.
Increase in genetic mutations
Woodard noted that previous research has shown that adolescents and young adults diagnosed with cancers commonly associated with old age tend to have a higher rate of heritable cancer mutations.
But, she explained, those rates are higher than once thought.
Woodard even cited a study of more than 1,000 adolescents between the ages of 18 and 39, noting that the results showed that about 21% of participants diagnosed with early-stage cancer had a germline mutation. Only 13% of the remaining patients had a germline mutation.
“This just highlights the fact that many of these young individuals have genetic mutations that can be passed on to their offspring,” she said. “Because these patients are younger, there are often problems with fertility and family formation.”
Fertility and Future Family Planning Concerns
According to Woodard, there are several genetic conditions associated with a greater risk of cancer. If people have any of these conditions, they probably want to do genetic testing. For example, she emphasized hereditary breast and ovarian cancer syndrome. Woodard noted that many of these patients may experience some form of infertility at a younger age than other people. These patients may also need to undergo risk-reducing surgery to prevent ovarian cancer.
Another condition, known as Li-Fraumeni syndrome, is associated with a greater risk of developing sarcomas, central nervous system tumors, breast cancer, and sex germ cell tumors — all of which, according to Woodard, negatively impact a person’s fertility.
That’s why, she said, many of these individuals need to participate in fertility preservation conversations with their healthcare team.
In addition, some of these cancers may require treatment that destroys a person’s ability to have children.
Fertility Preservation Methods
Woodard shared insight into some of the fertility preservation methods that people have access to. She noted that eggs, embryos and sperm can all be frozen for later use. Freezing of ovarian and testicular tissue are also possibilities, according to Woodard.
Another option available to patients who need radiation to the areas around their reproductive organs is gonadal shielding. In this case, radiology technicians use protective shields to minimize radiation exposure in certain areas.
People can also undergo an experimental approach known as ovarian suppression. Woodard explained that a gonadotropin-releasing hormone agonist is used in women to suppress the ovary during chemotherapy.
“The thinking is that a silent ovary is more resistant to the effects of chemotherapy than one that is actively cycling,” she said during her presentation.
However, she cautioned that the data available on this approach are quite variable.
Family building options
There are a myriad of options available to patients when they decide to start a family, Woodard explains. Depending on their comfort level, she said, the options available to patients range from natural conception to IVF and beyond.
For people who have premature ovarian failure due to their cancer treatment, there is an option to use donor eggs, sperm or embryos. There are also pregnancy carriers for women who may no longer have a uterus or who are at too high a risk of reaching full term.
And finally, Woodard noted that people can pursue adoption. However, she explained that it can sometimes be difficult for people with a history of cancer to adopt.
“Sometimes adoption can be challenging for cancer survivors because some agencies consider it too risky and don’t allow those patients to undergo any sort of initial screening,” she said. “Asking an adoption agency whether an early-stage cancer diagnosis will disqualify them is a very important question for patients to ask.”
Genetic testing for future children
Woodard concluded her discussion with a discussion of genetic testing methods available to patients to assess whether it is possible to pass on hereditary mutations to future children.
Patients who are already pregnant can use prenatal genetic testing, she said. Prenatal screening lets the parents know about the chances that the child has abnormal genetics. Diagnostic prenatal tests are slightly different in that they can show whether a fetus has a particular condition.
“The problem with prenatal genetic testing is that the patient is already pregnant,” she said. “If we find an abnormality, it really has some implications and has patients (who) make tough decisions about whether to continue the pregnancy or not.”
For those patients who are not yet pregnant and may be considering IVF, preimplantation genetic testing is a viable option.
Woodard explained that an embryo is tested after the first IVF before the embryo is transplanted back into the patient’s uterus. There are several types of preimplantation genetic tests, but one tests the embryo specifically for a specific gene.
“If a woman is a carrier of a BRCA mutation and she wants to test her embryo for that mutation, this is the type of test we would use,” she explained.
While some consider preimplantation genetic testing unethical or controversial — because some people use it for sex selection of their babies — Woodard noted that it’s a viable option for many trying to start a family without passing genetic mutations to their offspring. .
“(Pre-implantation genetic testing) … is an acceptable method to prevent transmission of mutations to offspring, but requires in-depth genetic counseling and support,” she concluded.
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