Who's at risk for colon cancer? - Amit H. Sachdev and Frank G. Gress
If you were to lay your digestive tract
out in a straight line,
it would form a tube
spanning nearly ten meters.
The last 1.5 meters of that
are called the colon, or large intestine.
Cells in this organ's lining
constantly renew themselves,
but the genes that moderate this process
occasionally go awry,
leading to the excessive growth
of new cells.
That results in small growths
or abnormal clumps of cells called polyps.
The majority of these polyps
won't do any harm,
but some can become cancerous
when their cells begin to grow
and divide rapidly,
projecting further into the colon.
At that point, they can transform
into colon cancer,
one of the most prevalent and
preventable forms of cancer in the world.
That's a slow process:
though growth times vary,
it often takes around ten years
for a small polyp
to grow and develop into a cancerous one.
We don't know exactly what causes
the majority of colon polyps
and colon cancers.
We do know in general that colon cancer
involves the activation
of what's called oncogenes in the polyp,
and/or the loss of tumor-suppressor genes
that usually keep cancer cells in check.
Most cells have proto-oncogenes
that help them grow.
When a proto-oncogene mutates,
or there are two many copies of it,
it can become a permanently
active oncogene
with cells that grow out of control.
While we don't yet know exactly what
underlying factors cause these changes,
experts suspect a combination
of both environmental
and inherited genetic factors.
In the worst cases, when cells within
polyps divide and spread unchecked,
they eventually break through
the lining of the colon.
Lymph and blood vessels carry
those cells all over the body,
and they can go on to form tumors.
Despite these challenges,
there's a solution.
We've become extremely good at
detecting and removing offending polyps
before they can cause cancer.
This happens through a process
called screening,
and when we do it regularly,
we can prevent many cases of colon cancer.
So, who's at risk?
Most cases occur in people
aged 50 years or older.
This group is considered at average risk
for colon cancer or colon polyps.
There's also a higher risk group
that includes people with personal
or family histories
of colon polyps or cancer,
and those who suffer
from inherited genetic syndromes,
or inflammatory diseases,
like Crohn’s disease
and ulcerative colitis.
So the best age to initiate screening
varies from person to person.
If you have access to healthcare,
it's best to consult a doctor
to find out when you should begin.
Screening can be done with various tests.
Colonoscopy involves
a long, thin, flexible tube
that's fitted with a video camera
and light at the end
and placed internally to examine
the colon for polyps.
If polyps are found, a doctor
can do a polypectomy,
a procedure that removes polyps
from the colonic wall.
Doctors can also then test
the polyp for cancerous cells.
Colonoscopy is the only test that can
be used to both find and remove polyps.
There are, however,
other useful screening tests,
including imaging
and at-home tests that can allow patients
to examine their stool
for small amounts of blood.
Occasionally, polyps are too large
to be removed during a colonoscopy,
in which case, the next step is surgery.
If blood and imaging tests then reveal
that cancerous cells
have spread outside the colon,
then a special treatment,
like chemotherapy,
may also be required to stop
the cancer from escalating.
We can also take on certain habits
to reduce our likelihood of developing
colon cancer in the first place.
There's evidence that maintaining
a healthy weight,
not smoking,
and being physically active can help.
But most importantly,
access to healthcare
and regular screenings
at crucial times in life
are the best ways to prevent colon cancer.
