When a
person receives a life-altering diagnosis like that of cancer, two questions
generally asked are: “Am I going to die?” and “Will my family get this, too?”
The
answer to the first question is long and complicated, and depends on a lot of
things. But the answer to the second question is getting clearer all the time,
all from a cheek swab or a blood test.
That’s
because advances in genetic testing are making hereditary cancers easier to
detect, and helping doctors and family members make better choices about
prevention and treatment.
Understanding familial cancer vs. hereditary cancer
First,
let’s distinguish between familial cancer and hereditary cancer. When cancer
runs in a family, but without an identified genetic cause, this is known as
familial cancer.
We
label a cancer as “familial” when we believe there is a genetic mutation that
contributes to the cancer seen within a family, but existing technology and
available knowledge (including the impact of environmental and lifestyle
factors) do not allow us to identify the genetic change that is causing it.
Hereditary
cancer, on the other hand, is diagnosed when genetic testing identifies a
“causative gene mutation”, or change in the gene related to the disease, that
can be passed from one generation to the next and has the possibility to — but
will not always — cause cancer.
Genetic mutations in hereditary cancers
Many
people are familiar with genetic testing for breast cancer. People with a
mutation in what is known as the BRCA gene, whether BRCA1 or BRCA2, are more
likely than others to develop breast cancer, and at a younger age. Women who
know they have this mutation usually get more frequent and intensive screenings
and in some cases, undergo preventative mastectomies to remove their breasts
and ensure they will never develop breast cancer.
People
with a mutation in what is known as the BRCA gene, whether BRCA1 or BRCA2, are
more likely than others to develop breast cancer, and at a younger age.
That
same BRCA gene mutation may increase your risk of ovarian cancer, pancreatic
cancer, melanoma and cancers in the fallopian tubes or abdominal cavity,
depending on which BRCA gene is damaged and where in the gene the damage
occurred. In some cases, women will also have their ovaries removed based on
the genetic findings in BRCA.
We also
can use genetic testing to look for other hereditary cancers.
For
example, Lynch Syndrome, historically referenced as a hereditary colon cancer
syndrome, is also linked to other types of cancer. These include ovarian,
pancreas, stomach, small bowel, bile duct, brain, certain kidney and urinary
cancers, certain skin cancers and endometrial cancer. Again, like BRCA, this
depends on which exact gene is involved, and where the mutation is located.
The importance of genetic testing
It’s
important to remember that heredity cancer doesn’t impact every patient and
family. But, the incidence of a hereditary predisposition for cancer is 1 in 10
cancer patients, far more than we ever estimated previously — and genetic
testing is underutilized.
Regardless
of the results, genetic testing can provide you, your family
and your physician with useful information.
If
results of genetic testing are negative, when applied with the right history
both within the patient and his or her family, there can be great relief for
people with cancer, knowing they are not passing the risk on.
But if
they’re positive, it’s very useful for doctors to monitor family members for
early detection, and to do screening earlier, more frequently and tailored with
more sensitive testing methods.
Early
detection screening is important for all people with either genetic or even
lifestyle risk factors to consider, especially when there is risk for cancers
that don’t have obvious symptoms, like pancreatic, ovarian or gastric cancer.
But other tests and more advanced imaging may help detect a cancer at an
earlier stage, meaning there is greater chance of survival and less chance of
recurrence.
How to make the most of genetic testing
The
field of genetic testing is exploding. Our technology and knowledge base is
increasing so much that I believe there will be a day when it becomes routine,
and you’ll carry a card with all that information.
But
we’re not there yet. So, what should a patient do?
A
cancer diagnosis can be overwhelming, and genetics may not be the first thing
you think of. But it’s important for you to be your own advocate and ask your doctor
what your genetic risk might be. You should also consider asking to be referred
to a certified genetic counselor for testing and consultation. Likewise, if a
family member has been diagnosed or there is a family history of cancer that
may be a concern, ask your primary care provider for a genetic counseling
referral.
Be wary
of direct-to-consumer testing that is frequently
advertised for both genealogy and hereditary risks. Many give false security
and are not complete genetic tests. If there truly is a medical concern, it
should be done by a lab with supervision.
No comments:
Post a Comment