03a: Colon Flashcards Preview

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Flashcards in 03a: Colon Deck (62):
1

Lifetime risk of colon cancer is (X)%

X = 5

2

Lifetime risk of colon adenoma is (X)%

X = 60

3

Which behavioral trends have led to the (increase/decrease) in colon cancer (incidence/mortality)?

Decrease; both

1. Decrease smoking
2. Improved diet/exercise
3. NSAIDs

4

T/F: an emigrating population acquires the colon cancer risk of the new environment

True - variation in geographic incidence may be related to diet

5

List the modifiable factors that increase risk for colorectal cancer

1. Red and processed meat intake
2. Obesity
3. Smoking and EtOH
4. DM II

6

List the modifiable factors that decrease risk for colorectal cancer

1. Physical activity
2. NSAIDs
3. Hormone replacement Rx
4. Dairy/Ca, folate

7

T/F: about 35-40% of colorectal cancer cases are sporadic

False - 75%

8

Classic Familial Adenomatous Polyposis: risk of colorectal cancer approaches 100% by age (X). Caused by (Y) gene mutation.

X = 40
Y = APC (chrom 5)

9

Patient is 25 years old with multiple (over 100) colorectal adenomas. Which genetic disease is he likely to have? What’s the mode of inheritance?

Classic FAP; autosomal dominant

10

(FAP/AFAP) presents with adenomas that are predominantly right-sided. What’s the mean age at which these polyps are seen?

AFAP

44

11

T/F: both FAP and AFAP are cause by genetic mutation in APC

True

12

MUTYH-associated polyposis mimics (X) disease phenotypically but has mutation in (Y)

X = FAP
Y = MUTYH (base-excision repair)

13

Hereditary Nonpolyposis Colorectal Cancer (HNPCC) aka (X) Syndrome: which age of onset? And predominance of cancer at which site?

X = Lynch

40 yo or under
Proximal colon

14

T/F: HNPCC results in multiple primary cancers (colorectal and extracolonic).

True

15

HNPCC: mutation in which genes?

DNA mismatch repair (MLH1,2, MSH6, PMS2)

16

List the two sequences of natural progression to colorectal cancer. What percent of CRC has followed each of these paths?

1. Adenoma-Carcinoma sequence (80%)
2. Serrated Adenoma Path (20%)

17

How long (timeline) is the Adenoma-Carcinoma sequence for colorectal cancer? List the steps

10y

Small adenoma, large adenoma, HG dysplasia, invasive cancer, metastasis

18

How long (timeline) is the Serrated Adenoma pathway for colorectal cancer? List the steps

15y

Microvesicular Hyperplasia, sessile/serrated adenoma/polyp, serrated adenoma, serrated cancer, metastasis

19

Individuals with one first-degree relative affected by CRC before age 60 have an (X)-fold increased lifetime risk of developing CRC. The risk applies/begins when they’re (older/younger/same age) as relative.

X = 2-3
Younger (10 y younger)

20

List the Amsterdam II criteria for (X) disease.

X = HNPCC

1. 3+ relatives with HNPCC associated cancer
2. 2+ generations of CRC
3. 1+ case before age 50

21

T/F: 95% of colorectal cancers are adenocarcinomas

True

22

Diagnostic method of choice for CRC

Colonoscopy

23

How might a CBC be helpful in diagnosing or verifying CRC?

Fe deficiency anemia (Sx of CRC in cecum)

24

CRC: best imaging study for detecting intra-abdominal spread ​of disease

Abdominal CT

25

CRC: Endoscopic ultrasound useful in assessing

depth of invasion and local lymph node status for rectal cancers

26

Carcinoembryonic antigen (CEA) serum levels can be used to monitor recurrence of (X) cancer after curative surgery

X = colorectal

27

T/F: Chemotherapy for advanced colorectal cancer (Stage IV) has proven incredibly successful.

False - v disappointing

28

Which type of therapy is recommended for Dukes’ C (node-positive) colon cancers?

Adjuvant Rx
Chemo (alone or with radiation) given post-op after curative resection

29

Which type of therapy is recommended for Dukes’ B2 and C rectal cancers?

Adjuvant Rx
1. Curative surgery
2. Chemo with high dose pre- and/or post-op radiation

30

Pt with no FHx of CRC: when do you start screening and how often by colonoscopy?

Age 50
Every 10y

31

Average risk patient: how often do you screen with flexible sigmoidoscopy?

Every 5 y OR
every 10 y with anual FIT (fecal immunochem test)

32

CRC screening: CT colonography can be used every (X) years or barium enema every (Y) years

X = Y = 5

33

36 y.o. Pt has older brother and father with PHx of CRC. Brother got it around 55 y.o. and dad at 60 y.o. How often do you screen your patient, and starting at what age?

Every 5 y (colonoscopy)

beginning at age 45 y.o. (10y before youngest affected relative)

34

Your 25 y.o. patient meets the Amsterdam II criteria, but refuses genetic testing. What are the screening criteria for CRC?

Assume she's positive for HNPCC - follow those guidelines;

Colonoscopy every 1-2y starting now (age 25) and then yearly after age 40

35

Patient with FAP - CRC screening criteria:

Flex sigmoidoscopy yearly beginning at puberty

36

Patient with AFAP - CRC screening criteria:

Colonoscopy every 1-2y beginning at age 25

37

MUTYH polyposis screening criteria

(Same as AFAP):
Colonoscopy every 1-2y beginning at age 25

38

The Classical APC, aka (X), pathway originates with mutation in (one/both) alleles of (Y) gene in which cell?

X = MSS (microsatellite stable)
Both
Y = APC
Stem cell in colonic mucosal crypt

39

CRC: APC mutation causes (X) cell to produce APC protein that has which issues?

X = stem cell (in colonic mucosal crypt)

Truncated - loses critical function of sequestering beta-catenin

40

CRC: beta-catenin protein, normally (stimulated/inhibited) by (X), has which roles?

Inhibited; X = APC

1. Cell-cell adhesion
2. Component of growth-promoting nuclear TF

41

APC pathway for CRC: the earliest lesion formed is termed (X).

X = aberrant crypt focus OR microadenoma

42

APC pathway for CRC: from a microadenoma, the next step is formation of (X). These small adenomas frequently contain up-regulated (Y) enzyme, which inhibits apoptosis.

X = tubular adenomas
Y = COX2

43

APC pathway for CRC: Mutation of (X) (oncogene/suppressor) frequently associated with large tubulovillous or villous adenomas.

X = KRAS
Oncogene

44

T/F: All colonic adenomas show at least low-grade dysplasia

True

45

APC pathway for CRC: (X) mutation has been associated with the step from low- to high-grade dysplasia

X = p53

46

Endpoint colorectal adenocarcinoma of APC pathway characterized by:

Chromosomal instability (but microsatellite stable) - chromosome breaks, losses, duplications, gene deletions

47

CRC Serrated Polyp Path: originates with mutation of (X) in which cell?

X = BRAF or KRAS (oncogene belonging to RAS-RAF-MAP kinase path)
Crypt stem cell

48

T/F: transformed appearance of cells in early part of Serrated Polyp Path is nearly identical to those of APC path.

False - distinct appearance of senescence (as opposed to dysplastic aberrant crypt foci in APC path)

49

T/F: Some BRAF/KRAS mutation in early polyps of serrated path pose no clinical risk of progression

True - if constrained by senescence

50

CRC Serrated Polyp Path: following BRAF/KRAS mutation, list the two variants of serrated polyps that are immediate precursors to cancer.

1. Sessile Serrated Adenoma
2. Traditional Serrated Adenoma

51

Sessile serrated adenomas are located mainly in (prox/distal) colon with (flat/serrated) appearance.

Proximal; flat (sessile)

52

T/F: Sessile serrated adenomas must pass through senescence process prior to progression to dysplasia/cancer.

False - can bypass senescence

53

CRC Serrated Polyp Path: (X) precursor to colon cancer can bypass senescence and progress by which process?

X = sessile serrated adenoma

Epigenetic CpG island methylation (inactivates tumor suppressor genes and mismatch repair gene hMLH1)

54

Serrated polyp path: Inactivation of (X) gene by CpG island methylation is crucial to progression of (Y) adenoma to colon cancer.

X = hMLH1
Y = sessile serrated

55

T/F: Sessile serrated cancers are microsatellite instable.

True

56

T/F: Serrated pathway cancers present in older adults, compared to APC path, with poor prognosis.

False - present in older adults, but good prognosis

57

Traditional serrated adenomas are located mainly in (prox/distal) colon with (flat/serrated) appearance.

Distal;
Serrated (tubulovillous)

58

T/F: Traditional serrated cancers are microsatellite instable.

False - MSS

59

Which colonic adenomas have pronounced eosinophilia of epithelial cells?

Traditional Serrated

60

Traditional Serrated Adenomas have (KRAS/BRAF) mutation.

Either (but BRAF more highly aggressive/incurable)

61

Traditional Serrated Adenomas: what are the important engines of progression to cancer?

1. CpG island methylation
2. Chromosomal instability

62

Sessile Serrated Adenomas have (KRAS/BRAF) mutation.

BRAF