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Surgery Core Topics > Colon Cancer > Flashcards

Colon Cancer Flashcards

0
Q

Incidence of colon cancer?

A

3rd m/c cancer
Affects women slightly more than men
72,600 cases (11%) men #3
75,700 cases (12%) women #3

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1
Q

Pathophysiology of colon cancer

A

Arises from “benign” adenomatous polyps (80% of time) in normal epithelium -> early adenoma -> intermediate adenoma -> late adenoma -> carcinoma.

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2
Q

Risk factors for colon cancer

A
  • Age
  • High fat
  • Colonic Polyps
  • PMH
  • FHx
  • UC or Crohn’s disease
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3
Q

Symptoms of colon cancer

A
  • Changes in bowel habits: diarrhea or constipation, color of stool (red, maroon or dark), -narrow or thin stool
  • Abdominal discomfort (with eating)
  • Weight loss
  • Anemia (microcytic)
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4
Q

Dark maroon, continuous bleeding

A

Right colon cancer, blood acted on by bacteria

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5
Q

Maroon blood

A

Transverse colon

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6
Q

Bright red blood

A

Rectal bleed

-Rectal cancer until proven otherwise!

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7
Q

Chance of polyp greater than 1 cm to become malignant after 20 years?

A

25%

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8
Q

Percentage of colon cancer associated with FAP or HNPCC?

A

6%

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9
Q

Screening for colon cancer?

A 
Average risk
-FOBT + Flex sig q5yr 
-DCBE q5yr
-Colonoscopy q10yr
High risk
-for large (1cm+) or multiple adenomatous polyps removed: Colonoscopy q3yrs. DCBE + Flex sig as alternative
-Family Hx: normal but start at 40yo
-Genetic syndromes: Annual flex sig at puberty if possible,
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10
Q

Of hereditary “germline mutations” what is the distribution of diseases?

A

90% Hereditary non-polyposis colon cancer (HNPCC) “Lynch syndrome”
10% FAP (Familial adenomatous polyposis)

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11
Q

Pathophysiology of FAP

A

It is a Gene defect: APC gene mutation.

  • APC is tumor suppressor gene
  • beta-catenin and c-myc downstream targets
  • AD inheritance
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12
Q

Presentation of FAP

A

“carpet of polyps” in colon, teens or early 20s.

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13
Q

Rx FAP

A

Total colectomy

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14
Q

Gardener’s syndrome

A

FAP with prominent benign extra-colonic manifestations (osteomas, cutaneous desmoids and fibromas)

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15
Q

Turcot’s syndrome

A

Colorectal cancer with CNS malignancies (medulloblastoma, astrocytomas, ependymomas (FAP) or glioblastoma (HNPCC)

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16
Q

FAP associated cancers

A 
Brain (medulloblastoma)
hepatoblastoma
Pancreas
thyroid
Biliary tree
Gastroduodenal
Periampullary
Hepatoblastoma
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17
Q

Gene defect in HNPCC

A

mutation in mismatch repair genes: hMLH1 in 95% of cases

18
Q

Inheritance of HNPCC

A

AD

19
Q

HNPCC associated cancers

A 
colorectal
endometrium
ovary
ureter
pancreas
brain - glioblastoma
20
Q

HNPCC-associated non-cancerous lesions

A
  • cafe au lait spots
  • sebaceous gland adenomas (muir-torre syndrome)
  • keratoacanthomas
21
Q

Patient with known FAP had colectomy 5 years ago. Does he need follow-up? What should you tell his family?

A

upper endoscopy with attention to duodenal and papillary area
Family should undergo genetic testing for mutated APC at age 12, adults full colonoscopy
Children <5 yearly alpha-feto-protein levels and liver imaging to look for hepatoblastoma

22
Q

Amsterdam II Criteria for diagnosis of HNPCC?

A
  1. 3+ relatives with HNPCC
  2. Colon cancer involves 2 GENERATIONS
  3. one diagnosed <50 years of age
23
Q

Screening of individual with family member diagnosed with CRC <55 years?

A

colonoscopy 5 years earlier than earliest cancer in the family

24
Q

M/C causes of rectal bleeding in 60+ year old male

A

Hemorrhoids > Colon cancer > AVM

25
Q

Palpation of sister mary joseph’s node

A

implies metastatic cancer

26
Q

3 most specific signs for CRC?

A

Rectal mass = pathognomonic
Rectal bleeding
Anemia

27
Q

Pre-op labs before CRC surgery?

A

CBC
Serum chemistry profile - serum electrolytes, BUN/creatinine
PT/PTT - bleeding? but best screening is past history of bleeding
Urine analysis - infx increases risk of surgery
Liver chemistries - check for mets
CEA - establish baseline for future post-op surveillance testing

28
Q

Postoperative surveillance labs?

A

CEA - most cost effective, 64% recurrences detected by first CEA
LFTs poor sensitivity and specificity, not recommended by ASCO

29
Q

What is CEA?

A

Carcinoembryonic antigen - glycoprotein expressed in the glycocalyx of gastro-intestinal mucosal cells esp in colon and rectum.

30
Q

Normal levels of CEA?

A

2.5-3.0 ng/mL in nonsmokers

5ng/mL in smokers

31
Q

How often is CEA elevated if patient has metastatic colorectal cancer?

A

85% of time. Not specific marker - Elevated in lung, breast, other GI esophageal, gastric, pancreatic malignancies.

32
Q

Is CEA used for routine screening?

A

No, sensitivity is 40%, not specific. Elevated levels associated with obesity, older age, smoking cigarettes, alcohol. 250 false positives for every one positive. Used as prognostic indicator for recurrence.

33
Q

Why is SMA-7 ordered preop?

A

Basic metabolic panel to assess electrolyte abnormalities in hypertensive patient who may be using a diuretic.

34
Q

Is neoadjuvant chemoradiation therapy indicated for CRC?

A

Colon - Generally not indicated.
Rectal - very useful in some patients with locally advanced rectal cancer: Decrease recurrence in pelvis, shrink tumor, facilitates negative margin resection

35
Q

Margins acceptable in rectal cancer resection?

A

5 cm proximally
distal margin of at least 2 cm
full resection of lymphovascular pedicle to include at least 12 lymph nodes

36
Q

Describe the series of NSIM (assuming each step is positive for cancer or suspected cancer) for patient with 3x2 cm fixed mass on posterior wall of rectum 4 cm above levator muscles.

A

Anoscopy -> Biopsy -> Colonoscopy -> CT Scan -> Surgery or neoadjuvant

37
Q

Screening for patients with FAP

A

Flex sig each year at puberty

38
Q

Screening for patients with HNPCC

A

flex sig at 25

39
Q

Workup for colon cancer

A

CEA, CXR, abdominal, pelvic CT, CBC, platelets, chem,

40
Q

Gene in FAP

A

APC gene, tumor suppressor, AD with 90% penetrance, 5q21

41
Q

Gene in HNPCC

A

DNA mismatch repair genes, 80% lifetime risk.

42
Q

Cancers associated with HNPCC

A

Colon
Endometrial - 40%
Stomach - 15%
Ovarian 10%

Surgery Core Topics (9 decks)

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