E2: Colon Cancer Flashcards
What is it called when there is a growth on the inner surface of the colon?
A polyp
What is pedunculated polyp?
A polyp that is attached to the colon by a stem or stalk
What is a flat polyp called?
Sessile
What are the 4 types of polyps?
- hyperplastic (non-neoplastic)
- Pseudopolyps (non-neoplastic)
- Adenomas (neoplastic)
- Sessile serrated polyps
What is the most common type of polyp?
Adenomas (2/3s of all colon polyps)
What does most colorectal cancer arise from?
Adenomas
What classifies as an “advanced” Adenoma?
- ≥1cm
- villous component
- high grade dysplasia
The risk of CRC increases by what 3 things?
The number, size, and histology of adenomas
What are the 3 kinds of adenoma polyps and what is the most common?
- Tubular adenoma (most common)
- Tubulovillous adenoma
- villous adenoma
What is the 2nd leading cause of cancer deaths in the US?
Colorectal cancer
95% of CRC are ***.
Adenocarcinomas
Where does CRC most commonly occur?
-Left sided is most common, but right sided cancer rates are rising
What are the risk factors for CRC?
- Personal or family history of CRC/adenomas, familial adenomatous polyposis, or HNPCC
- Personal history of inflammatory bowel disease
- age >50
- African American
- tobacco use
- alcohol
- high fat/low fiber and red meat intake
- DM
What is the clinical presentation of CRC?
- Patients are often asymptomatic
- Red flag symptoms: Change in bowel habits, hematochezia, IDA, anorexia, abdominal pain
What are the blood tests to evaluate for CRC?
- CBC: evaluate for IDA
- liver tests: alk phos may be elevated with liver Mets
- Carcinoembryonic antigen (CEA): not used for screening, but helpful for prognostic indicator and monitoring for recurrence
What are the scans you can order to evaluate for CRC?
- Colonoscopy: permits biopsy for pathologic confirmation
- CT chest, abdomen, and pelvis to demonstrate tumor extension, complication, regional lymphatic and distant metastases
What might you see on barium enema that is suggestive of CRC?
Apple core lesion
What is the management of CRC/
- Partial collectors with wide margins and adjacent lymph node removal
- chemotherapy (if Mets)
- radiation (commonly for rectal adenocarcinoma)
What is used for surveillance for CRC?
- Serial CEA levels
- annual surveillance CT chest/abd/and pelvis
- periodic colonoscopy
What are the visualization tests you can use to screen for CRC?
Colonoscopy, flex sig, and CT colonography
What are the stool based tests used to evaluate for for CRC?
-gFOBT, FIT, and FIT DNA
What is the gold standard to diagnose CRC?
Colonoscopy
What are the advantages of colonoscopy?
- Ability to visualize the entire colon
- able to detect and remove polyps to prevent them from turning into cancer
- high sensitivity for CRC and advanced adenomas
- single session
- Long screening intervals
What are the disadvantages of colonoscopy?
- Highest cost, limited access
- bowel prep
- invasive
- complications
- sedation and chaperone
- no infalliable
What are the advantages of Flex sig?
- limited prep
- no sedation
- lower cost
- lower risk than colonoscopy for perforation
What are the disadvantages of Flex sig?
- Only reaches the distal 1/3 of the colon, deficiency in protect against proximal lesions
- if polyps are found, need colonoscopy to r/o proximal lesions
What is a CT colonography?
-A virtual colonoscopy that produces 2D/3D images of the bowel mucosa
What are the disadvantages of a CT colonography?
- can miss flat or small polyps
- unable to remove polyp, would need colonoscopy
What is the main limitation for the stool based tests in detecting CRC?
Most polyps do not bleed and these tests detect blood
What are the limitations of the gFOBT (high sensitivity hemoccult SENSA)?
- Requires 3 consecutive stools
- dietary modifications required
- if positive result, needs COY
- Sensitivity for one time screening is not ideal, annual use is recommended
What are the dietary modifications that must be made prior to the gFOBT test?
Avoid red meat, iron supplements, Vitamin C, and NSAIDs
How does the FIT test work?
Tests for the presence of human hemoglobin
How does the FIT-DNA test work?
-combines FIT with testing for DNA mutation bio markers in cells shed by CRC
What are the disadvantages of the FIT-DNA?
- there are increased false positives when compared to FIT
- require entire bowel movement
What is the preferred stool test for CRC?
FIT, though COY is still gold standard
When should you start CRC screening if the patient has a single 1st degree relative with CRC or a documented adenoma diagnosed <60, or with more than two 1st degree relative diagnosed at any age?
Colonoscopy every 5 years beginning at age 40 or 10 years younger than the age at which the youngest 1st degree relative was diagnosed
When should you start CRC screening in a patient who has a single 1st degree relative with CRC or documented advanced adenoma diagnosed >60?
Begin screening at 40 and if normal, screen as average risk individual
What is familial adenomatous polyposis (FAP)?
- An autosomal dominant APC gene mutation that results in >100 adenomatous polyps that emerge at around 16 years old
- nearly 100% will progress to CRC by age 39 if untreated
What is the typical recommended treatment for FAP?
-Prophylactic colectomy
What are the extracolonic malignancies that people with FAP are at increased risk for?
- gastric/duodenal/ampullary carcinoma
- follicular or papillary thyroid cancer
- hepatoblastoma
- CNS tumors
When should you start screening patients with FAP? How should you screen?
- sigmoidoscopy/colonoscopy starting at 10-12 yo and repeating every 1-2 years
- routine EGD recommended
- Screen for extracolonic malignancies (thyroid US etc)
What is hereditary Nonpolyposis colon cancer (HNPCC)?
- AKA lynch syndrome
- an autosomal dominant germline mutation in one of severeal DNA mismatch repair genes that results in increased risk for CRC, usually between ages 45-60
What other malignancies are very common with HNPCC?
-Endometrial is most common, may also have ovarian, small bowel, gastric, renal/ureter/bladder, brain
What is the criteria that is used to evaluate if a patient has lynch syndrome? What does the criteria require?
- Amsterdam criteria
- 3-2-1 rule: 3 affected family members, at least two from successive generations, and at least one diagnosed before age 50
When should you starting screening for CRC in patient with HNPCC?
-Annual colonoscopy beginning between ages 20-25, or 2-5 years prior to the earliest age of CRC diagnosis in the family
