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MCC > Wk 6 Colorectal Cancer > Flashcards

Wk 6 Colorectal Cancer Flashcards

1
Q

Peak incidence of CRC?

A

60-70 years

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2
Q

What are the 2 major pathways for CRC to arise?

A
  1. adenoma-carcinoma sequence (~80%)
  2. microsatellite (repeats of non-coding DNA) instability (MSI)
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3
Q

What is HNPCC?

A

= Heriditary non-polyposis colorectal carcinoma
-inherited mutation in DNA mistmatch repair enzymes (in all cells)
-increased risk for colorectal, ovarian and endometrial cancers
-colorectal carcinoma arises de novo at a relatively early age, usually right sided

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4
Q

What are 2 mechanisms for colorectal carcinoma screening?

A
  1. colonoscopy
  2. fecal occult blood testing
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5
Q

How does left-sided CRC grow?

A

Napkin-ring lesion / apple core
-> decreased stool caliber (thin poop),
LLQ pain,
blood-streaked stool
-more common than right sided
-more associated w/ adenoma-carcinoma sequence

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6
Q

How does right-sided CRC grow?

A

As a raised lesion/ bump of colonic mucosa
-> IDA due to small amounts of bleeding and vague pain
-more associated w/ microsatellite instability

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7
Q

What do patients w/ CRC have an increased risk for?

A

Streptococcus bovis endocarditis

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8
Q

Describe CRC staging

A

T: depth of invasion
N: spread to regional lymph nodes
M: distant spread - most commonly involves the liver

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9
Q

What are 3 things tumor markers are used to assess?

A
  1. screening
  2. assess tx response
  3. assess/detect recurrence
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10
Q

What is a CRC serum tumor marker?

A

CEA = carcinoembryonic antigen
-useful for assessing tx response and recurrence
-not useful for screening

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11
Q

What is a colonic polyp?

A

Raised protrusions of colonic mucosa

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12
Q

What are the 2 most common types of polyp in the colon?

A
  1. hyperplastic polyps
  2. adenomatous polyps
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13
Q

Characteristics of hyperplastic polyps

A
  1. “serrated” appearance due to hyperplasia of glands
  2. most common type
  3. usually arise in left colon (rectosigmoid)
  4. benign w/ no malignant potential
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14
Q

Characteristics of adenomatous polyps

A
  1. neoplastic proliferation of glands
  2. 2nd most common colonic polyp
  3. benign but premalignant - may progress to adenocarcinoma via the adenoma-carcinoma sequence
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15
Q

What are 3 mutations in the adenoma-carcinoma sequence

A
  1. APC (TS) mutations (sporadic or germline - FAP) increase risk for polyp formation
  2. K-RAS mutations ->polyp formation
  3. p53 mutation and increased COX expression -> progression to carcinoma

APC mutation = risk
K-RAS mutation = formation of polyps
p53 mutation & increased COX = progression

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16
Q

What can protect against adenoma-carcinoma sequence?

A

aspirin b/c it’s a COX inhibitor

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17
Q

How are polyps treated during a colonoscopy?

A

All polyps are removed and examined microscopically

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18
Q

What are 3 factors in the risk of progression from adenoma to carcinoma?

A
  1. related to size, >2 cm
  2. sessile growth (flat vs pedunculated like a mushroom, flat is worse) sessile serrated covering entire depth of crypt
  3. villous history (villi seen in histology vs tubular adenoma, villous is worse/the villan)
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19
Q

What is FAP?

A

=familial adenomatous polyposis
1. autosomal dominant
2. 100s-1000s of adenomatous colonic polyps
3. due to inherited APC mutation on chromosome 5

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20
Q

What is tx for FAP?

A

Remove colon and rectum
otherwise almost all patients develop carcinoma by 40 yo

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21
Q

What is Gardner syndrome?

A

=FAP w/ fibromatosis and osteomas
-fibromatosis = non-neoplastic proliferation of fibroblasts, usually in retroperitoneum, locally destructive
-osteomas = usually benign tumor of bone, usually arises in skull

22
Q

What is Turcot syndrome?

A

=FAP w/ CNS tumors (medulloblastoma and glial tumors)

23
Q

What is a juvenile polyp?

A

=sporadic hamartomatous (benign) polyp that arises in children (<5)
-usually presents as solitary rectal polyp that prolapses and bleeds

24
Q

What is a hamartoma?

A

A tumor that arises w/ normal (for the area) but disorganized tissue

25
Q

What is juvenile poylposis?

A

=multiple juvenile polyps in the stomach and colon
-large numbers increases the risk of progression to carcinoma

26
Q

What is Peutz-Heghers Syndrome?

A

=hamartomatous polyps throughout GI tract
-mucocutaneous hyperpigmentation on lips, oral mucosa, and genital skin
-autosomal dominant disorder
-increased risk for colorectal, breast and GYN cancer

27
Q

Inflammatory polyps

A

1

28
Q

Solitary rectal ulcer

A

-a type of inflammatory polyp
-not actually solitary
-if sphincter cannot relax completely, physical trauma from passing of stool -> mucosa can become pedunculated
-> hemoptasis

29
Q

3 signs of epithelial dysplasia

A
  1. nuclear hyperchromasia
  2. elongation of nuclei
  3. nuclear stratification

-adenoma implies dysplasia is present

30
Q

Sessile vs pedunculated

A
31
Q

Villous vs tubular adenoma

A
32
Q

Name this adenoma

A

Tubulovillous adenoma

33
Q

What adenomous pattern is associated w/ increased Ca risk?

A

villous pattern

34
Q

Views of adenocarcinoma of colon

A
35
Q
A

Pedunculated tubular adenoma

36
Q
A

Hyperplastic polyp

37
Q
A

adenocarcinoma

38
Q

4 colon Ca comorbidities

A
  1. IBD
  2. Type 2 Diabetes
  3. Prior Cancer
  4. Hx of polyp
39
Q

Hereditary/genetic colon Ca

A
  1. FAP
  2. HNPC/ Lynch Sydrome
  3. 1st degree relative w/ CRC
40
Q

7 Modifiable Colon Ca Risk Factors

A
  1. heavy EtOH
  2. Obesity (BMI>30)
  3. Hyperlipidemia
  4. red meat (100g/day)
  5. Processed meat (50g/day)
  6. Smoking
  7. High sucrose diet
41
Q

What gene mutation -> 80% of all CRC?

A

APC gene
-inherited and acquired

42
Q

Clincal presentation of CRC

A
  1. hematochezia
  2. change in bowel habits & stool shape
  3. abd discomfort (gas pain, bloating, cramps)
  4. unexplained weight loss
  5. constant fatigue - IDA
43
Q

R vs L-sided CRC

A

R - midgut: cecum, ascending transverse
-flatter polyps, harder to detect

L- descending, sigmoid

44
Q

What are the 2 stool-based tests for CRC?

A
  1. gFOBT = guaiac fecal-occult blood test
    2.Fecal immunochemical test = FIT
45
Q

What does gFOBT test?

A

Indirect measurement of blood in stool: peroxidase activity
-not meant to rule out GI bleed
-requires 3 stool tests
-avoid specific foods and meds prior
-sensitivity: 62-79%
-specificity: 87-96%

46
Q

What is the FIT?

A

=fecal immunochemical test
-direct measurement of Hb in stool
-1 stool sample
-no dietary or med restrictions
-sensitivity: 73-92%
-specificity: 91-97%

47
Q

2 CRC test modalities besides stool tests

A
  1. CT colonography
  2. colonoscopy (gold standard)
48
Q

Where might you find an applecore lesion?

A

in the colon
-circumferential, large and deeply invasive
-usually very advanced colon cancer

49
Q

How is colon cancer staged?

A
  1. how deeply does it penetrate the wall - deeper is much worse px
  2. has it spread to the lymph nodes? Has it gone past the lymph nodes? Most often to liver b/c of portal vein
50
Q

What does metastatic colon cancer look like in a lymph node?

A
51
Q

What is an osteoma?

A

Benign bony growth

52
Q

What does mucin look like?

A

The white
-mucin made b/c colon cancer from adenocarcinoma

MCC (44 decks)

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