-hello, i'm doctor karnes and i'm gonnabe talking to you today about colorectal cancer and how you can prevent it. the objectives are to answer a few questions - who gets colon cancer and why, what is my risk for getting colorectalcancer, how can i reduce my risk for colorectal cancer, how do i choose the best screening test,how often do i need to get screening, and what should i look for in a specialist ora center? key facts about colorectal cancer in2015 - it ranks second behind lung cancer as acause of cancer deaths
but among non-smokers colon cancerprevents or replaces lung cancer as the numberone cancer killer. one in 20 people will get colorectal cancer in theirlifetime without screening. we know that polyps are the precursors to almost allcolorectal cancers. and over half of us will develop polyps bythe time we're age 70. most pre-cancerous polypsprovide a nice 10-year window of opportunitybefore they become cancer. that's the time when they can be foundand removed. and up to 90% of colorectal cancers can be prevented throughlifestyle changes and the removal of these
pre-cancerous polyps. colonoscopy is the gold standard to finding these polyps and it's the only test we have that allows us to remove them. but unfortunately 40-50% of us still down recommended screening. risk factors for colorectal cancer include things that we can't change, such as our age, gender, race, and family history and things that wecan change including how much we exercise, diet, ourweight, and our lifestyle. colon cancer
increases the older we get. in otherwords the longer you have your colon, the more likely it isyou're gonna get colon cancer. as you can see from this slide it begins to increase at about age 50. males are a little bit more common, are more likely to get colon cancer than females. if you have a gene that actually predisposes you to getting colon cancer your risks could be very high. withfamilial adenomatous polyposis, shown in the top curve, the risk approaches100% by age 70. race also matters,
african-americans have the highest rateof colorectal cancer, followed by native americans and native alaskans, followed by whites, asian and pacific, and hispanics seem to havethe lowest risk. and we all think that family history is big deal and it is a big deal in colorectal cancer, but if we look at all the cancersdiagnosed 75% of these people have no family history ofcolon cancer, remaining 25% do and a small percentage of those 5% overall
have hereditary colon cancer caused by aspecific gene. the lifetime risk if you have no familyhistory getting colon cancer is about 5 percentbut the range is anywhere from 2 to 14 percent. if youhave a family history of colon cancer your lifetime risk is about 10 percentbut the range could be anywhere from five to 27 percent. if you have a gene that you're born with that predispose you to colorectal cancer againyour risk could be as high as 100% but the overall risk reallydepends on what the
syndrome is that you're born and could range anywhere from 10 to 100 percent. much of this huge range in each of these categories is related to modifiable risk factors in other words things that you canchange in your life that can reduce your risk of colon cancer. if you're this guy on the left he doesn't exercise, is obese, drinks too much, he smokes too much, he has type 2 diabetes and eats a lot red meat and processedmeats, your risk getting a colorectal
cancer could be increase by nearly threefold and youcould have a 27 percent chance of getting it if you have a family history as well. ifyour this woman on the right who exercises, takes aspirin, folic acid,calcium, fiber supplements, and eats plenty of fruits and vegetables, you risk can be reduced by 60 percent or 0.4x what your risk would otherwise be. well how does colon cancer develop? it develops in the lining of the colon
which is a single layer of cells on thesurface of the colon that then folds in these pits as you can see here. at thebase of these pits are stem cells, these are the cells from which all of the cells from your colon come from and their stem cells in each of the pits of our colon. the stemcells divide, they grow and move up the crypt, then instructions tell the cells to stopgrowing to start doing their job which might beto absorb fluid and electrolytes or secrete mucous and then once they reach the top at thecrypt their
program to die through a process calledpertussis. this entire process only takes three days well as you can imagine if anything goeswrong with these processes you could developcolorectal cancer and we do know that genes control allthese processes and that mutations to these genes are what causes colon cancer so as polyps develop, grow turn into cancer and then spread there'san accumulation of mutations to a variety of genes, mutations may-
mutations to these genes may tell cells to keep growing when they should bestopping, fail to die or detach invade migrate anddisseminate. here's some examples of colon polyps these are benign and you can see they'reall shapes and sizes. they can be as small as one or twomillimeters or as large as three or four inches before they becomecancer but you can never predict on the based on the size of a polyp whether theremay or may not be cancer there. the risks developing a cancer in a polyp
increase as the polyp gets larger. here's anexample colorectal cancers and what's sad aboutthese cases they were all benign polyps five to 10years ago. so there's a window of opportunity wehave to prevent colon cancer and that occurs before the cancerdevelops early on during the first fifty yearso f ourlife if we practice primary prevention in other words reduced the modifiable riskfactors for colon cancer we can reduce the chances of gettingpolyps and cancer
once we have polyps there's reallyonly one way to prevent cancer from forming and that's to find the polyp and get it out. keep in mind that even if you're perfect and your modifiable risk factorslike doctor oz, you could still get colorectal polyp. sohere's this window of opportunity for prevention colon cancer for the cancer develops. well how do wego about preventing colon cancer trying to find early enough so that itdoesn't kill us? we do that by screening you we basically have three differentways we can screen. we can focus on preventative screeningtechniques
early detection screening techniqueswhere we try to find cancer early or we can just simply wait forsymptoms. prevention again occurs during theearliest phases colon cancer development up to the polyp phase but before the cancer phase. early detection occurs when colon cancer hasformed but has not advanced or spread to the point where yoursurvival is significantly reduced. as you can see on theright side of the slide
colon cancer as it grows begins to invades and spread the chances of survival godown dramatically. up to stage 3 colon cancer where the cancer hasescaped to the lymph nodes but not elsewhere surgery still gives you a 75 percentchance of cure. if you wait for symptoms that usuallymeans the colon cancers become very large it's starting to obstruct or its starting tobleed if you wait until then there's a
50-50 chance you will not be cured insurgery. here's some examples of some screening tests available to us. fecal tests just test your stool, they test for blood for the test for abnormaldna there's radiographic test, which themost common commonly use now is the ct colonographyor the virtual colonoscopy which can actually reproduce your colonin three dimensions and allow the radiologists to see polyps in your colon virtually and then there's endoscopic techniquessuch as colonoscopy
that allows us to actually look at thepolyp and remove the polyp. fecal screening tests include fecal orhemoccult blood test. many of us are familiar with takingstool and putting it on a little card sending to the doctor to be tested forblood. if these are done every one to two years there has been shown to be a reductionin colon cancer related deaths by 15-33 percent. these techniques did not fine polyps verywell the fecal occult blood test fines partsabout 10 percent of the time and colon cancer about fifty percent of the time. if you have a positive test and then have a
colonoscopy chances that a cancer will actually be found is only 2 to 5 percent. the fit test is a newer stool blood test that is more sensitive and specific it can find polyps 15 to 30 percent ofthe time and colorectal cancers 65 to 75 percentof the time we still don't know how well it reducescancer related deaths because it hasn't been around long enough for us to knowthat and finally the newest test on the blockis
stool dna test or cologuard. this isa stool test that looks for mutations in the stool that - come from shed colon cancer cells this is done every two years it's alittle better at finding polyps up to 50 percent of the polyps can be found with this test and it's a little better at finding cancers well up to 95 percent of cancers can be found. ct colonography that's a test that wewould perform every five years is comparable to colonoscopy finding polyps
if they're bigger than about 5millimeters. it misses flat polyps requires a good quality prep just likecolonoscopy. it also requires radiation exposure and a positive result warrants yougetting a colonoscopy to find the abnormality seen on the ct colonography to see its something that needs to beremoved. so here here's a slide the basically puts allthese things together if your primary interest is preventingcolon cancer you gonna reduce your modified risk factors
early on and then you can choose eithera colonoscopy where you gonna choose ct colonographyif it's positive for something and get your colonoscopy. if your choice isto go with early detection you'll do fecal testing with any of the three fickle tests thati mentioned that being the most commonly used today if positive you get your colonoscopy andif colonoscopy actually finds a cancer you you go into surgery, if you choose towait for symptoms
then once you have your symptomsobviously you go straight to colonoscopy and hopefully if there's a cancer therecausing your symptoms the surgery will be able to cure you butagain there's only about a 50 percent chance that's going to happen. as you can see all of these commondenominators colonoscopy. so in with the advent of screening that began back in the mid 1980s there's been a decrease in the incidenceof colorectal cancer shown in the red line at the top of the slide.
as the incidence of colorectalcancer ours the- as the frequency screen is increased theincidence of colorectal cancer has dramatically decreased. we know thatcolonoscopy prevents colon cancer from a number of studies, but the most important which was national polyps study in 1993 which showed 70 to 90 percent reduction expected incidents of colorectal cancerthose who had colonoscopy. 20 years later participants in this study were lookedat again
and those that participated with colonoscopy had a 53 percent reduction in expected deaths caused by colon cancer. today we know that 91-93% of new colorectal cancers occur in people who had not had a colonoscopy within the last five years whereas seven to nine percent of new colorectalcancers diagnosed occur in people who have had acolonoscopy within the five years. these are called interval cancers and is one of the things we as
colonoscopies really want to put a lid on. so why do people get interval colorectal cancer? you had a colonoscopy the colonoscopists may or may not have found polyps, they told you come back in five years or comeback in 10years, what happened why did i end up getting colon cancer within five years? well there's four possible explanations thecolonoscopist may have missed a polyp or cancer in your colon, they maynot have removed your polyp entirely and less some behind, it may bethat the pathologist misread the polyp, or it may be that polyps can form
into cancer just that quick in between two colonoscopies just five years apart. well most investigators believe that the greatest number of interval cancersoccur because we miss them as colonoscopists or we don't removethose polyps well enough. thats eighty-five percent intervalcancers are responsibility of the coloscopists sothe quality of your colonoscopy really does matter. what are your risk factors of gettingcolorectal cancer? we know that this you had a colonoscopyand the exam
was not complete in other words itdidn't reach the top of your colon your odds of getting interval cancer are increased by seven-fold. it alsomatters who's doing your colonscopy, if they'renot gastroenterology trained, the risk of interval cancers do tend to be highersuch as with rural surgeons, family practitioners, internist, and urban surgeons. adenoma detection rate
is the colonoscopists new battingaverage well what are adenomas? adenomas are pre-cancerous polyps the adenoma detection rate is thepercent of screening colonoscopies in which one ormore these adenomas is found so a colonoscopist wants to have a high batting average or a high adr , the national average adenoma detection rate is in 25 percent ofscreening colonoscopies, adenomas will be found, but it's extremelyvariable between colonscopists. some only find
adenomas in 10 percent other screen cases whereas others may find adenomas in up to 50 percent of screencases. it's estimated that the true adenoma prevalence is probably greater than 50 percent. gi docs do have the highest performance and it should be comforting to know that coming to an academic center where you may have agi fellow was a gi trainee performing a colonoscopy itseems to have no effect on the adenoma detection rate.
adenoma detection really matters this isa large study done by the kaiser group showing that the highest adenoma detection rate is associatedwith the lowest interval cancer rates. as you can see youon the right side of the slide there's a group of 12 colonoscopists whohad very high adenoma detection rates ranging between34 and 53 percent those people at a reduced risk of interval cancer your have about 0.220.65 so what you look for in a colonoscopist? they should ensure that
you're getting the best possible prep because if your prep isn't goodenough they're not gonna find polyps. s split dose prep is better than single dose prep and 4l isbetter than lower volumes the last dose of a the split dose prep should be taken 5 hours priorto the procedure. your colonoscopist should have good cecal intubation rate. a cecal intubation rate is the rate at which they get to the top of the colun inother words they've seen all of your column should be greaterthan 95 percent.
your colonscopist should take care tolook behind every fold use irrigation to wash off mucus anddebris and take time in withdrawal and in fact with we found that: withdrawal times less than six minutesan anomaly detection rate is much lower every colonoscopist should also record the prep quality in the reportand recommend early repeat colonoscopies you prepwasn't very good. they needs another their adr achieve an adr greater than 30 percentthats adenoma detection rate
and have a repertoire of skilled polypectomy techniques so they know how to get eventhe big ones out. they should follow the guidelines for screening andsurveillance and here's some examples of when weshould - are the recommendations for firstscreening colonoscopy. for average risk non-african americans we should begin screening at age forty,this is for average risk individuals if you're african-american somesocieties are recommending starting at age 45 because your risk of getting coloncancer is higher
and getting colon cancer earlier. if youhave a family history of colorectal cancer or advanced polyps you should start at age 40 or begin 10years younger than the age is the youngest affected relative when they were diagnosed. when should colonoscopies be repeatedhow often should they be done? the recommendations on this slide do notapply to people who have hereditary colorectal cancersyndromes if you've never had a prior polyp and nofamily history of colon cancer
colonoscopy is recommended every 10years if your colonoscopist finds just one or two small adenomas they could have you comeback in five years or as long as 10 years. if you have more than two in other words3-10 pre-cancerous adenomas you should comeback in three years for your next colonoscopy and if you have more than 10 you should come back much less than that in fact if you have 10 or more adenomasyou should consider saying genetic counselor for possiblegenetic syndrome
if you have one or more largepre-cancerous or advanced adenomas come back in threeyears and if you have a single pre-cancerouspolyp greater than 2 centimeters she should be coming back in three tosix months. how can i tell if i ever hereditary syndrome? one in three hundred people carrymutation for lynch syndrome which is the most common colon cancerhereditary syndrome. people with lynch syndrome are alsopredispose to a variety of other cancers most commonly endometrialcancer
or uterine cancer also stomach cancer,ovarian cancer, and less likely biliary tract cancer, urinary tract cancers, small bowelcancers, brain tumors. if you the best way to to get some ideas to ayou may have a syndrome is the first look at your personal history and yourfamily history for colorectal cancer or lynch cancers particularly underage 50 if there's twoor more people in your family closely relatedwith colorectal cancer
and syndromes at any age consider thepossibility an inherited calling colon cancersyndrome if you have 10 or more pre-cancerous polyps consider inherited cancer center alsolook at immediate family members who may have already been diagnosed withhereditary colon cancer syndromes such as lynch,familial adenomatous polyposis which is fap, peutz-jeghers, cowdens, or map if you have family members whothese conditions see geneticist and get tested if youhave a family history of colorectal
cancer or an inherited colorectal cancersyndrome the intervals between colonoscopies ismuch shorter if you don't have a syndrome but do you have a familyhistory of colorectal cancer advance polyps should begin at age 40 or 10 years younger then the age of the earliest diagnosis of your family member and have your colonoscopy every five years if you have lynchsyndrome begin screening early between ages 20and 25 and continue screening for the
rest of your life every one to two years to help you preventgetting a colorectal cancer if you have familial adenomatous polyposis, screening begins at puberty and itcontinues every year for as long as you continue to have your colon. with fap as you may recall the risk of gettingcolorectal cancer can approach a hundred percent and many of these people require havingcolons out before that happens keep in mind that even with hereditarysyndromes
proper screening can help you preventcolorectal cancer. thank you very much.
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