CMPP -- Colon Polyps and Colorectal Cancer

fecal occult blood test (FOBT)

guaiac-based testing indirectly detects the HEME portion of hemoglobin breakdown; common to blood from all sources; resistant to degradation in the intestine

red meat, horseradish, broccoli

what foods can give one a false positive in FOBT?

ASA, NSAIDs, Vitamin C

what medications can give one a false positive in FOBT?

three times on three different days

due to the intermittent bleeding pattern of tumors, FOBT should be performed...

Fecal Immunochemical Test

test for CRC that reacts with antibodies specific for GLOBIN portion of human hemoglobin molecule;

delayed return of sample

what can lead to false negatives in FIT?

heme/peroxidase activity, entire GI tract

FOBT tests for _____, and it detects bleeding from________.

globin, lower GI

FIT tests for _____, and it detects bleeding from________.

Stool DNA testing

relies on stool detection of abnormal neoplastic cells shed from tumor; may be able to detect high grade adenomatous polyps OR colonic malignancies; done via collection of stool sample x 1

clear liquids x 24 h

bowel prep with colonoscopy recommendations

patient prep for a CT colonography

thin rectal catheter is placed, colon is distended with air or CO2, scanned in supine and prone position

no IV/PO contrast needed

how CT colonography is performed

acute colonic inflammation, recent diverticulitis, recent colorectal surgery, recent colon biopsy, bowel perforation/obstruction

when is a CT colonography contraindicated?

Flexible Sigmoidoscopy

limited endoscopic evaluation that can visualize the colon for up to 60 cm; however, cancer/polyp detection is only good for this area (poor visualization of right sided cancers); can be performed without sedation

two sodium phosphate enemas given the morning of the procedure

how to bowel prep for a flexible sigmoidoscopy

Colonoscopy

the GOLD STANDARD for screening/diagnosis of CRC/polyps; biopsy and polyp removal are possible with this procedure

good bowel prep -- poor bowel prep limits visualization of right sided cancers

need for anesthesia/transportation

need for hold of anticoagulation

drawbacks to colonoscopy

family hx of colon cancer

personal hx of colon polyps OR colon cancer

IBD

who is considered "high risk" for colon cancer

COLONOSCOPY IS ONLY RECOMMENDED SCREENING TEST

what is the recommended screening test for those with a high risk for colon cancer?

first degree relative with CRC BEFORE age 60

two or more second decree relative

who meets the criteria for having a family history of colorectal cancer?

Age 40 OR 10 years before youngest CRC diagnosis (whichever is earlier)

when to start screening those who have a family history of colon cancer

every 5 years

frequency of screening for CRC in high risk patients

clear liquid diet -- NO RED/PURPLE LIQUIDS

--> no "stuff" in it

NPO after midnight

diet preparation for colonoscopy

Miralax with bisacodyl + Gatorade

Commercial preparations available by prescription

bowel preparation for a colonoscopy

Streptococcus gallolyticus

group D strep that is a common cause of endocarditis and bacteremia; considered a risk factor for CRC

Colonoscopy

Negative -- repeat in 4-6 months

If STILL negative -- screen as average risk adult

if one has Streptococcus gallolyticus endocarditis/ bacteremia, what should they do once it has resolved

Colon polyps

a protuberance of tissue into the lumen above the surrounding colonic mucosa; usually asymptomatic, but occasionally can ulcerate and bleed, cause tenesmus (if in rectum), cause obstruction (if large); may be neoplastic or non-neoplastic

Adenomatous polyps

Most carcinomas of the colon are believed to arise in these preexisting lesions

more common in men

large adenomas are more common in black populations (R sided) -- screening starts at 45

risk factors for adenomatous polyps

pendunculated (stalked)

flat

depresssed

sessile (flat based)

types of adenomatous polyps

sessile villous adenomatous polyps

most cases of CRC develop from what kind of polyps?

high fat low fiber diet

smoking

obesity

diet high in red meat

older age

male sex

risks for developing adenomatous polyps

must visualize entire colon

repeat colonoscopy every 3-5 years

if one visualizes an adenomatous polyp on sigmoidoscopy, what is the next step?

adenomatous polyps are thought to require >5 yers of growth before becoming clinically significant

what is the significance of the timeframe for screening of polyps?

Familial Adenomatous Polyposis (FAP)

autosomal dominant trait that results from a genetic mutation resulting in defective colonic mucosa; results in abnormal proliferation pattern and impaired DNA repair; causes innumerable colonic polyps that appear during childhood

start at age 10 or 12

when to start screening patients with FAP for CRC

yearly flex sigmoidoscopy -- once polyps identified, screening transitions to yearly colonoscopies

test to order to screen those with FAP for CRC

total colectomy

patients with FAP will eventually require a...

NSAIDS and celecoxib (Celebrex)

what medications are shown to decrease the number and size of polyps in FAP?

Lynch Syndrome (HNPCC)

autosomal dominant syndrome that is characterized by the lack of polyps; they will often develop cancer without preceding polyps (and it usually IS NOT in the colon, but they are still high risk)

Endometrial carcinoma

other sites include ovary, stomach, small bowel, breast, and prostate

what is the most common Lynch syndrome associated cancer

48 y/o, right sided lesions

when and where do patients with Lynch syndrome typically get CRC?

Amsterdam II criteria

3 or more individuals with Lynch-related cancers (CRC, endometrial, small bowel, transition cell, ureter/renal pelvis);

2 successive generations of Lynch-syndrome related cancers;

1 Lynch-related cancer dx <50yo

3 or more individuals with Lynch-related cancers;

2 successive generations;

1 Lynch-related cancer dx <50yo

3-2-1 rule

asymptomatic at early stages, varies based on anatomic location of tumor

clinical presentation of CRC

may become large without any changes in bowel habits (can be v liquid)

commonly ulcerate

chronic insidious blood loss without a noticeable change in the stool color, fatigue, palpitations, iron-deficiency anemia

clinical presentation of right sided CRC

stool becomes more formed as it passes through the transverse colon and into the left colon -- tumors in this area are more likely to cause obstruction, abdominal cramping

APPLE-CORE LESION

presentation of a left-sided CRC

hematochezia

tenesmus

narrow stool, ribbon stool

anemia may be less common

how does a rectosigmoid colonic malignancy present?

COLONOSCOPY -- localize/biopsy

flexible sigmoidoscopy is NOT a recommended test -- misses right sided tumors

how to work up CRC

get biopsy and await pathology results

staging (CT abdomen/pelvis +/- PET scanning)

tumor markers

steps after colonoscopy in CRC

TNM system

T- tumor spread

N- node involvement

M- presence of distant metastasis

spreading through lymph nodes and portal venous system

how does metastasis of CRC usually occur?

LIVER -- usually goes here first!

what is the most common site of mets from CRC

spreads via paravertebral venous plexus and therefore bypasses the portal system to reach lungs

distal rectal cancer does NOT usually metastasize to the liver first -- where does it go and why?

CEA (carcinoembryonic antigen)

tumor marker for CRC, but has low diagnostic ability to detect primary CRC; can be elevated in non-cancer related conditions; role is in FOLLOW UP of people already diagnosed with CRC.

used to see prognosis/how patient is responding to care

role of CEA in CRC