- Both genetic and environmental factors can lead to the development of different types of cancer.
- Genetic counselors and testing can help identify the potential cancer risks your genes may hold.
- This can help shape how you and your family might be screened and treated for cancer well into the future.
- Genetic testing can help mitigate some risks and identify some cancers sooner when they do occur.
When she was a senior in high school, Maggie Miller’s aunt was diagnosed with breast cancer.
“It was a really rough road,” Miller told Healthline, explaining her aunt was only 48 years old at the time.
“She had an aggressive bilateral mastectomy, aggressive chemotherapy in an era where management of nausea wasn’t very good, and radiation and reconstruction,” Miller continued. “It was really hard. And, I mean, I remember my mom being really emotional and being really worried. She has five daughters.”
At the time, there were very few answers regarding what the risks to the rest of her family may be. But today, Miller is part of a growing field of medical professionals who focus specifically on helping others identify those risk factors when breast cancer strikes someone they love: genetic counselors.
Miller is a certified genetic counselor working at the Providence Cancer Center in Anchorage, Alaska.
According to the Bureau of Labor Statistics, she was one of only 3,000 working genetic counselors in the United States in 2018.
“As a genetic counselor, I kind of think of myself as an interpreter of genetics,” Miller explained. “It’s a really complicated field that involves a little bit of psychology, a little bit of genetics, a little bit of counseling, a little bit of basic science, and it just merges a lot of things.”
Her training required taking courses in almost every department of medicine. “But really, it’s a process of looking at a cancer or a person who has cancer and trying to establish if there’s a genetic cause behind it.”
If she can find that genetic cause, she says, it can shape how a family might be screened and treated well into the future, ideally mitigating risks and identifying cancer sooner when it does occur.
While Miller works with a variety of cancer genes, breast cancer is one of her personal passions and specialties.
According to Miller, 60 to 70 percent of breast cancers are environmental, “or what we call sporadic,” she said, noting that 5 to 10 percent of breast cancer diagnoses are hereditary.
“You’ll notice there’s a gap in those numbers,” Miller explained. “There are also some breast cancers that have genes involved but it’s not a single gene, it’s more complex. That’s really what we’re trying to identify in genetic testing is, okay, can we find the people that have the high-risk genes.”
However, she points out not everyone has the high-risk genes, even when there is some gene involvement. And not all cancers are purely environmental either. Sometimes, it’s a combination of the two.
To explain the three different categories of breast cancer (sporadic, hereditary, and a combination of the two), Miller advises her patients to think of a seesaw.
“Most breast cancer is sporadic,” she said. “And if you picture a seesaw, when the seesaw hits all the way to the right hand side, that’s cancer.”
But it often takes a lifetime of little pebbles falling on the seesaw for that to happen, which is why the average age for breast cancer diagnosis is 62 years of age. It’s an accumulation of “a lot of junk” over time, as Miller put it, eventually resulting in the development of breast cancer.
When a woman is diagnosed with breast cancer in her 30s or 40s, however, it’s usually an indication that something else is going on.
Miller explained this is where her bricks versus pebbles theory comes in. The bricks would be those high-risk genes that cause the seesaw to tip faster, or that involve the seesaw tipping for multiple members in a family.
But those genes don’t ensure a person will get cancer. They just mean a person is at greater risk.
“So it takes other pebbles to tip their scale,” Miller explained. “But they often tip younger and it runs from generation to generation.
It’s all an accumulation of risks, where high-risk genes add the most weight at once to the scale, but pebbles can be added through outside factors at any time.
After the 60 to 70 percent of breast cancers that are sporadic and the 5 to 10 percent that are hereditary, Miller says the remaining “30 percent or so” are what she calls “familial.” It’s also referred to multifactorial.
With multifactorial, there are genes involved, but not the big, high-risk bricks. Instead, it’s a bunch of little genetic pebbles combined with a bunch of environmental pebbles.
“So in a multifactorial model, you’d often see siblings getting the same cancers,” she said. This is because they share not only the same genes, but often the same environment.
That’s where genetic testing and counseling enters the picture, helping people to understand their risk and assess the choices available to them for mitigating those risks.
But though it occurs less frequently in men, when a man is diagnosed with breast cancer, “his chance of having a BRCA mutation is about 20 percent,” said Miller.
She further explained that the risk of developing breast cancer for a man with a BRCA mutation is 7 percent, while the average woman with a BRCA mutation has a risk of 13 percent, which often comes down to hormones.
But a 7 percent risk is nothing to scoff at, especially when we consider that men rarely undergo the same breast cancer screenings as women. This can mean their cancers take longer to diagnose.
Also, men who carry a BRCA mutation can pass that mutation down to their daughters.
“Men who carried mutations are also at risk for prostate cancer,” Miller added.
For these reasons, she is passionate about ensuring men know that if they have family members with the BRCA mutation, they could be impacted as well. Which means men with family histories should consider genetic testing, as well as self-breast exams and clinical breast exams.
The science of genetic testing is rapidly evolving, with new gene links being discovered all the time.
“There’s almost always something new for me to understand in terms of a new gene or a new gene mutation within a gene that we had previously missed,” Miller explained.
That’s one of the reasons The American Society of Breast Surgeons has issued guidelines advising people who have undergone previous genetic testing to consider the benefits of being tested again.
Beyond that, they want genetic testing made available to anyone who has a personal history of breast cancer. The guidelines recommend starting testing with the affected family member first, but argue that testing should be made available to family members when testing the originally impacted patient isn’t available.
So, why not just test everyone?
The answer, according to Miller, often comes down to logistics.
“Not all insurance carriers pay for it,” she explained.
Miller also pointed out that many “labs offer patient assistance for families that can’t afford that.”
Miller said the limited numbers of genetic counselors currently available also plays a big role in how many people can be tested and those who are available often have very full referral schedules.
Additionally, not everyone wants to know what their genetic screening might reveal. So, they opt out altogether.
“Sixty to 70 percent of my referrals never make an appointment,” Miller said, explaining that there is a whole subset of our population that does not see this type of information as empowering.
While Miller says she sees the potential benefits of population testing, she thinks “we need to figure out a lot of management issues and a lot of communication issues and support issues before we just go full steam ahead.”
However, for those who fear what the results of genetic testing may reveal, Miller says she wants to make sure people know that even with the high risk genes, there are a lot of options available that may not involve some of the drastic measures people often fear.
While there are surgical and medical options to consider, there are also advanced screenings for those at greater risk that can help catch breast cancer sooner.
“Even in the worst of all the cancer syndromes, I have great tools to offer people,” Miller said.