00:00
Welcome back, thanks for joining me
on this discussion of colon
cancer
under the section of large intestines.
00:09
What are the causes of colon cancer?
I'll give you a second
to think about this.
00:16
Here's some very important
colon cancer risk factors.
00:20
Low fiber,
high fat diet,
we call this the Western diet,
there are very important hereditary
syndromes to be aware of gene mutations
from a polyp all the way to cancer
in a predictable fashion.
00:35
And inflammatory bowel disease, including
ulcerative colitis and Crohn's disease,
ulcerative colitis and Crohn's
disease will be covered
in your medicine lectures.
00:47
Let's start
with one of the very important syndromes
hereditary nonpolyposis,
colorectal cancer,
HNPCC.
00:57
HNPCC are typically described
as either Lynch Syndrome one or Lynch
Syndrome two.
01:05
Lynch Syndrome
one is an autosomal dominant phenotype
and classically associated with a DNA
mismatch repair gene MLH
or MSH on your examination
when presented with a particular DNA
mismatch repair gene.
01:22
Look for these as the answers
in Lynch syndrome two,
it's similar to an autosomal dominant
Lynch syndrome one, except that
now you have extracolonic cancers,
particularly endometrial
or ovarian.
01:39
Petz-Jeghers, another important
syndrome, autosomal dominant phenotype.
01:46
These are classically associated
with hematomas which are benign in the GI
tract,
also associated
with Mukulcutaneous pigmentation.
01:56
However,
although the hematomas are benign,
there is an increased risk of associated
GI cancers,
not derivatives of the hematomas.
02:09
How about familial adenomatous polyposis?
These are multiple colon polyps
and usually in the thousands.
02:18
There is a APC or adenomatous
polyposis coli gene,
which is a tumor suppressor gene mutation.
02:25
And as a reminder, in general,
when a tumor suppressor
gene mutation
occurs, there's no tumor suppression.
02:33
Just like many of the other
polyposis syndromes,
this is also autosomal dominant in nature.
02:39
Typically, you'll find hundreds
or thousands of polyps
and there's almost 100% guarante
of risk of colon cancer
due to the pure volume of polyps.
02:48
Shortly we'll discuss the very predictable
line of polyp to colon cancer
and why often FAP patients will require
surgery.
02:59
Gardner syndrome
under high yield syndrome again
associated with colon polyposis,
this is considered a subset
of familiar adenomatous polyposis
that we just talked about,
and the difference here is
that it's a multiple polyposis syndrome
that's associated with extra
colonic manifestations such as Desmoid
tumors, sebaceous cysts, lipomas and osteomas.
03:25
When you're presented
with the clinical scenario
that show extra colonic manifestations
as well as polyposis,
remember Gardner syndrome.