L7: Colon polyps and cancer Flashcards
2 Non-neoplastic polyps (benign hyperplastic)
Hyperplastic
Pseudopolyps
Who gets pseudopolyps?
IBD (they’re inflammatory)
2 classifications of Neoplastic polyps
Adenomas
Sessile serrated polyps
Facts about adenomas
2/3 of all colon polyps
Common in adults older than 50
Usually asymptomatic, large→ +/- bleed
Risk of colorectal cancer increases by number of adenomas, size, histology→ influences surveillance interval recommendations
70% of colorectal cancers arise from adenomas, takes 10 years→ Early detection & removal is key
Most common adenoma which causes 95% of colorectal cancers
Tubular adenoma
Types of adenomas
Tubular adenoma (most common)
Tubulovillous adenoma
Villous adenoma
An adenoma is considered “advanced” if…
1 cm
villous or tubulovillous
high grade dysplasia
Colorectal cancer is more common in the ______ colon
Left sided colon, but right sided rates are rising
Risk factors for colorectal cancer
Adenomas or colon cancer Familial adenomatous polyposis Hereditary nonpolyposis colon CA >50 years, but rising in younger adults 8-10 years of IBD African american Tobacco, ETOH High fat/low fiber Red meat, Obesity, DM
Colorectal cancer presenation
*Often asymptomatic* Cachetic Pallor Lymphadenopathy Abdominal distention, ascites, mass, organomegaly DRE→ hemoccult (+), rectal mass
Colorectal cancer red flags
Change in bowel habits Hematochezia or occult blood in stool *Iron Deficiency Anemia* Anorexia/Weight loss Abdominal Pain
Colorectal cancer diagnostics
CBC→ chronic blood loss→ iron deficiency anemia
Elevated Alk phos→ liver mets
Carcinoembryonic antigen (CEA) → prognostic indicator, monitor for recurrence *Not used for screening*
Colonoscopy→ biopsy to confirm
Chest/abdominal/pelvic CT→ tumor extension/complication, regional lymphatic and distal metastasis
Barium enema→ “apple core lesion”
Colorectal cancer mangement
Partial colectomy with wide margins and adjacent lymph node removal
Chemo→ metastasis
Radiation→ rectal adenocarcinoma
Colorectal cancer surveillance
Serial CEA levels
Annual surveillance CT chest/abd/pelvis
Periodic colonoscopy
What’s CEA used for again?
prognosis
monitor for recurrence
NOT for screening
Gold standard for colon cancer screening
Colonoscopy
Colonoscopy sees
Flex sig sees
CT Colonography sees
Colonoscopy: entire colon
Flex sig: 60 cm=distal 1/3 of colon, less protection against right-sided cancer
CT Colonography: “virtual”, 2D/3D imaged of bowel mucosa, sees polyps >1 cm but can miss small or flat ones
Considerations for colonoscopy
Requires bowel prep, sedation/chaperone, time off work
Risk of perforation/bleeding
Not infallible:
1. Operator dependence
2. Poor prep→ precludes adequate visualization→ misses small/flat polyps
Considerations for flex sig
Limited prep, no sedation
Lower cost
Lower risk of perforation
Considerations for CT colonography
Requires bowel prep No sedation Lower risk of perforation Air insufflation with rectal tube Radiation exposure Incidental extracolonic findings
If a flex sig is positive
colonoscopy to rule out proximal lesions (right sided)
If a CT colonoscopy is positive
Colonoscopy
The thing to remember about screening tests that check for blood
most polyps don’t bleed
gFOBT definition
Fecal occult blood test (FOBT) , “stool Guaiac”
Identifies hgb by peroxidase reaction→ (+) blue paper
Hemoccult Sensa (gFOBT)→ take home, better sensitivity
FIT definition
FIT=Fecal Immunochemical Test
Noninvasive test for presence of human hemoglobin
Preferred colorectal detection test
FIT-DNA definition
FIT+ testing for altered DNA biomarkers in cells shed by CA
Noninvasive, expensive
Excellent negative predictive value
Which stool test requires a special diet?
gFOBT
avoid red meat, iron supps
Vit C, NSAIDS
Stool tests and false positives
gFOBT>FIT-DNA>FIT
Stool tests specimen
gFOBT: 2 specimens on 3 consecutive stools
FIT: Single specimen of spontaneously passed stool
FIT-DNA: Entire bowel movement
Start colon cancer screening at _____ for most individuals
50 years (average risk) 45 years (african americans)
For high risk individuals, start colon cancer screening _______
Single first degree relative with colorectal cancer or advanced adenoma <60 years OR 2 1st degree relatives diagnosed at any age
Screen at 40 OR 10 years younger than age at which relative was diagnosed
Single first degree relative with colorectal cancer or advanced adenoma >60 years OR 2+ first degree relatives
Screening at age 40→ normal→ screen as average risk individual
Discontinue colon cancer screening…
Up to date with screening
Negative prior screening
Age 75 or life expectancy <10 years
For colon cancer screening among individuals aged 76-85
more beneficial in healthy adults who have never been screened
(depending on age/comorbidities)
For colon cancer screening among individuals aged 76-85
more beneficial in healthy adults who have never been screened
(depending on age/comorbidities)
Familial Adenomatous Polyposis genetics
Autosomal dominant APC gene mutation
Hereditary Nonpolyposis Colon Cancer genetics
Autosomal dominant
Germline mutation in a DNA mismatch repair gene
Lynch Syndrome
Hereditary Nonpolyposis Colon Cancer
Familial Adenomatous Polyposis presentation
> 100 adenomatous polyps begin to emerge at 16 years→ all develop cancer by ~39 if untreated
Increased risk of extracolonic manifestations:
Gastric/duodenal/ampullary carcinoma
Follicular or papillary thyroid cancer
Hepatoblastoma in children, CNS tumors
Familial Adenomatous Polyposis management
Genetic testing/counseling Prophylactic colectomy Screening: SIgmoidoscopy/colonoscopy annually starting at age 10-12 until age 40 Routine EGD Screening for extracolonic malignancies
Hereditary Nonpolyposis Colon Cancer presentation
Increased risk of (right-sided) cancer by 45-60 years
Lifetime risk increased 22-75%
Multiple family members affected
Increased risk of multiple cancers:
Endometrial, ovarian, gastric, small bowel, hepatobiliary system, renal/ureter/bladder, brain
Hereditary Nonpolyposis Colon Cancer management
Genetic testing/counseling
Screening:
Annual colonoscopy at 20-25 years OR 2-5 years prior to earliest diagnosed relative
Screening for extracolonic malignancies:
Pelvic + endometrial biopsy
Transvaginal ultrasound
EGD at 30-35 years q2-3 years
3-2-1 rule
Amsterdam Criteria:
Diagnosis of Hereditary Nonpolyposis Colon Cancer
3 relatives across 2 successive generations, 1 diagnosed <50 years
