Colon Polyps and Cancer Flashcards
What is a polyp?
Growth on inner surface of colon
How a polyp might look on endoscopy
Pedunculated (attached by stem/stalk)
Sessile (flat)
*they influence the screening tests
Histologic classifications of polyps
Hyperplastic (non-neoplastic and benign)
Pseudopolyps (nonneoplastic-IBD/UC)
Adenomas (neoplastic and pre-cancerous)
Sessile serrated polyps (pre-cancerous)
Types of adenomatous polyps
Tubular adenoma (most common)
Tubulovillous adenoma
Villous adenoma
Tell me about colon adenomas
2/3 of all polyps
Common in adults>50
Usually asymptomatic (large may bleed)
More than half of colorectal cancers arise from these (progression about 10 yrs so early detection and removal)
When is a polyp a high risk adenoma?
“Advanced”
>1 cm, villous component, high grade dysplasia
When does the risk of colorectal cancer increase with adenomatous polyps?
The number, size and histology (influence surveillance intervals)
Sites of colorectal cancer
Left sided is most common presentation
Right sided rates are rising tho
Non-modifiable risk factors of colorectal cancer
Personal or family hx (adenomas or colon cancer, FAP or HNPCC-hereditary sxs)
Age >50
IBD>8-10 yrs
African American
Modifiable risk factors of colorectal cancer
Tobacco use Excess alcohol consumption Diet (high fat and low fiber or more red meat) Obesity Diabetes
Red flags in the presentation of colorectal cancer
Change in BH Hematochezia or occult blood in stool Iron deficiency anemia Anorexia/weight loss Abd pain
Presentation of colorectal cancer
Often asymptomatic
Cachetic, pallor, LAD
Abd distension, ascites, mass, organomegaly
DRE-hemoccult positive or rectal mass
Diagnostics for colorectal cancer
CBC-for IDA Liver tests (alk phos with liver mets) Carcinoembryonic antigen Colonoscopy Chest/abd/pelvic CT to look for tumor
What is carcinoembryonic antigen used for?
Prognostic indicator and monitor for recurrence of colorectal cancer
Colon cancer on imaging
Classic apple core lesion
How to stage colon cancer
Depth of tumor invasion
Status of regional nodes
Presence of absence of mets
Surveillance needed for colorectal cancer
Serial CEA levels
Annual surveillance with CT chest/abd/pelvis
Periodic colonoscopy
Screening vs surveillance
Screening is early detection looking for early stage of precancerous lesions in asymptomatic ppl with no history
Surveillance (follow up testing in pts with polyps, CA or IBD)
Types of preventative tests for colon cancer
*detect colon polyps and CRC
Colonoscopy, flex sig, CT colonography, double contrast barium enema no longer used!
Stool tests for colon cancer
*detect but don’t precent cancer
gFOBT
FIT (fecal immunochemical test)
FIT-DNA (cologuard)
Colonoscopy for colon cancer
Gold standard (diagnostic and therapeutic)
- See whole colon, remove polyps and take biopsies
- Detect precancerous lesions and CRC
Downside to colonoscopy
Invasive
Risk of major complications like perf or bleeding
Operator dependence
Colonoscopy following a polypectomy
Surveillance depends on number, size and histoloy
Check with the endoscopist
Flex sig for colon cancer
Lower benefit in protection against right sided colon CA
If find polyps, probably need colonoscopy to r/o proximal lesions
-Limited prep, no sedation, lower cost and lower risk of perf
Downside to CT colonograpy for colon cancer
Can miss flat or small polyps (virtual)
There is also radiation exposure (no sedation but need bowel prep)
What must be done with a positive CT colonography
Colonoscopy
What is gFOBT?
Fecal occult blood test- stool guaiac (indicates hgb by a peroxidase rxn)
-Hemoccult SENSA is a take home test and recommended
2 specimens on 3 consecutive stools
False positives
Diet before gFOBT
Avoid red meats, iron supplements, Vit C and NSAIDs
Preferred colon cancer detection test
FIT
FIT colon cancer test
Non invasive
Tests for presence of human hb and less false positives than FOBT
Single specimen of spontaneous stool
No diet restrictions
What is FIT-DNA (cologuard)?
Combines FIT with testing for altered DNA biomarkers in cells shed by CRC not polyps
Good - predicting value but more false positives
Expensive and requires entire bowel movement
When to start colon cancer screening for avg risk individuals with no sxs and no risk factors?
Begin CRC screening at age 50 (age 45 for African Americans)–consider colonoscopy and FIT first
When to start colon cancer screening for pt with single first degree relative diagnosed less than 60 YO?
Colonoscopy every 5 yrs starting at 40 or 10 yrs younger than age at which youngest 1st degree relative was diagnosed
When to start colon cancer screening for pt with single first degree relative diagnosed older than 60 YO?
Begin screening at 40 and if normal, then screen as avg risk individual (every 10 yrs after that)
When to stop colon cancer screening?
When pts are: Up to date with screening Negative prior screening (esp with colonoscopy) Age 75 Life expectancy <10 yrs
At what age to stop considering colon cancer screening
85 (depending on comorbidities)
Another says start at 50 and continue until 75
After how many years should all the tests be performed?
Colonoscopy- 10 CT- 5 Flex sig- 5-10 gFOBT- annual FIT- annual FIT-fecal- 3 yrs
What is familial adenomatous polyposis (FAP)?
Autosomal dominant due to APC gene mutation
>100 adenomatous polyps (began about 16 YO)
At when do pts with FAP develop colon cancer?
Usually by 39 YO if untreated (need prophylactic colectomy)
–Increased risk for extracolonic malignancies
Extracolonic malignancies seen in FAP
Gastric/duodenal/ampullary carcinoma
Follicular or papillary thyroid cancer
Hepatoblastoma (kids)
CNS tumors
Screening recommended for FAP
Those who are gene carriers or have family hx w/o genetic confirmation
Need colonoscopy or flex sig starting at 10-12 YO until 40 YO if negative
Also routine EGD
What is hereditary nonpolyposis colon cancer (HNPCC)?
Autosomal dominant lynch syndrome due to germline mutation in DNA mismatch repair genes
Multiple family members are affected
Risk associated with HNPCC
Increased risk for colon cancer (usually right sided) at about ages 45-60
What types of cancers are pts with HNPCC at risk for?
Endometrial (most common), ovarian, gastric, small bowel, hepatobiliary system, renal/ureter/bladder, brain
Amsterdam criteria to diagnose HNPCC
3-2-1 rule (3 affected members, 2 generations and 1 under 50)
Screening for HNPCC
Annual colonoscopy starting between 20-25 or 2-5 yrs prior to earliest age of colon cancer diagnosis in family
Also for extra colonic malignancies (pelvic exam, EGD etc)
When to consider hereditary colon cancer syndromes
FH or CRC in >1 family member
Personal or FH or CRC at early age (<50 YO)
Personal or FH of multiple adenomas (>10-20)
Personal of FH of multiple extracolonic malignancies
