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Surgical Recall > Chapter 47: Colon and Rectum- Colorectal Ca > Flashcards

Chapter 47: Colon and Rectum- Colorectal Ca Flashcards

1
Q

What is it?

A

Adenocarcinoma of the colon or rectum

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2
Q

What is the incidence?

A
  • Most common GI cancer
  • Second most common cancer in the United States
  • Incidence increases with age starting at 40 and peaks at 70 to 80 years
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3
Q

How common is it as a cause of cancer deaths?

A

Second most common cause of cancer deaths

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4
Q

What is the lifetime risk of colorectal cancer?

A

6%

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5
Q

What is the male-to-female ratio?

A

≈1:1

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6
Q

What are the risk factors?

A

Dietary: increased rates correlated with

  • Low-fiber
  • high-fat diets

Genetic: Family history is important when taking history

  • FAP
  • Lynch’s syndrome

IBD: Ulcerative colitis > Crohn’s disease

Age

previous colon cancer

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7
Q

What is Lynch’s syndrome?

A

HNPCC = Hereditary NonPolyposis Colon Cancer

  • autosomal-dominant inheritance of high risk for development of colon cancer
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8
Q

What are current ACS recommendations for polyp/colorectal screening in asymptomatic patients without family (first-degree) history of colorectal cancer?

A

Starting at age 50, at least one of the following test regimens is recommended:

  • Colonoscopy q10 yrs
  • Double contrast barium enema (DCBE) q5 yrs
  • Flex sigmoidoscopy q5 yrs
  • CT colonography q5 yrs
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9
Q

What are the current recommendations for colorectal cancer screening if there is a history of colorectal cancer in a first-degree relative <60 years old?

A

Colonoscopy at age 40, or 10 years before the age at diagnosis of the youngest first-degree relative, and every 5 years thereafter

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10
Q

What signs/symptoms are associated with the following conditions:

Right-sided lesions?

A

Right side of bowel has a large luminal diameter, so a tumor may attain a large size before causing problems:

  • Microcytic anemia
  • occult/melena more than hematochezia PR
  • postprandial discomfort
  • fatigue
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11
Q

What signs/symptoms are associated with the following conditions:

Left-sided lesions?

A

Left side of bowel has smaller lumen and semisolid contents:

  • Change in bowel habits (small-caliber stools)
  • colicky pain
  • signs of obstruction
  • abdominal mass
  • heme(+) or gross red blood
  • Nausea, vomiting
  • constipation
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12
Q

What is the incidence of rectal cancer?

A

Comprises 20% to 30% of all colorectal cancer

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13
Q

What are the signs/symptoms of rectal cancer?

A

Most common symptom is hematochezia (passage of red blood ± stool) or mucus; also:

  • tenesmus
  • feeling of incomplete evacuation of stool (because of the mass),
  • rectal mass
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14
Q

What is the differential diagnosis of a colon tumor/mass?

A
  • Adenocarcinoma
  • carcinoid tumor
  • lipoma
  • liposarcoma
  • leiomyoma
  • leiomyosarcoma
  • lymphoma
  • diverticular disease
  • ulcerative colitis
  • Crohn’s disease
  • polyps
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15
Q

Which diagnostic tests are helpful?

A
  • History and physical exam (Note: ≈10% of cancers are palpable on rectal exam)
  • heme occult
  • CBC
  • barium enema
  • colonoscopy
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16
Q

What disease does microcytic anemia signify until proven otherwise in a man or postmenopausal woman?

A

Colon cancer

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17
Q

What tests help find metastases?

A
  • CXR
    • lung metastases
  • LFTs
    • liver metastases
  • abdominal CT scan
    • liver metastases
  • other tests based on history and physical exam:
    • head CT scan for left arm weakness looking for brain metastasis
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18
Q

What is the preoperative workup for colorectal cancer?

A
  • History
  • physical exam
  • LFTs
  • CEA
  • CBC
  • Chem 10
  • PT/PTT
  • type and cross 2 units PRBCs
  • CXR
  • U/A
  • abdominopelvic CT scan
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19
Q

By what means does the cancer spread?

A
  • Direct extension:
    • ​circumferentially and then through bowel wall to later invade other abdominoperineal organs.
  • Hematogenous:
    • portal circulation to liver lumbar
    • vertebral veins to lungs
  • Lymphogenous: regional lymph nodes (LNs)
  • Transperitoneal
  • Intraluminal
20
Q

Is CEA useful?

A

Not for initial screening but for baseline and recurrence surveillance (but offers no proven survival benefit)

21
Q

What unique diagnostic test is helpful in patients with rectal cancer?

A

Endorectal ultrasound

  • probe is placed transanally and depth of invasion andnodes are evaluated
22
Q

How are tumors staged?

A

TMN staging system

23
Q

Stage I

A

Invades submucosa or muscularis propria

T1–2

N0

M0

24
Q

Stage II

A

Invades through muscularis propria or surrounding structures but with negative nodes

T3–4

N0

M0

25
Q

Stage III

A

Positive nodes, no distant metastasis

any T

N1–3

M0

26
Q

Stage IV

A

Positive distant metastasis

any T

any N

M1

27
Q

What is the approximate 5-year survival by stage:

Stage I?

A

90%

28
Q

What is the approximate 5-year survival by stage:

Stage II?

A

70%

29
Q

What is the approximate 5-year survival by stage:

Stage III?

A

50%

30
Q

What is the approximate 5-year survival by stage:

Stage IV?

A

10%

31
Q

What percentage of patients with colorectal cancer have liver metastases on diagnosis?

A

≈20%

32
Q

What are the common preoperative IV antibiotics?

A

Cefoxitin (Mefoxin®)

carbapenem

33
Q

If the patient is allergic (hives, swelling), what antibiotics should be prescribed?

A

IV Cipro® (ciprofloxacin) and Flagyl® (metronidazole)

34
Q

What are the treatment options?

A

Resection: wide surgical resection of lesion and its regional lymphatic drainage

35
Q

What decides low anterior resection (LAR) versus abdominal perineal resection (APR)?

A

Distance from the anal verge and pelvis size

36
Q

What do all rectal cancer operations include?

A

Total mesorectal excision

  • remove the rectal mesentery including the LNs
37
Q

What is the minimal surgical margin for rectal cancer?

A

2 cm

38
Q

How many LNs should be resected with a colon cancer mass?

A

12 LNs minimum = for staging, and may improve prognosis

39
Q

What is the adjuvant treatment of stage III colon cancer?

A

5-FU and leucovorin (or levamisole) chemotherapy (if there is nodal metastasis postoperatively)

40
Q

What is the adjuvant treatment for T3–T4 rectal cancer?

A

Preoperative radiation therapy and 5-FU chemotherapy as a “radiosensitizer”

41
Q

What is the most common site of distant (hematogenous) metastasis from colorectal cancer?

A

Liver

42
Q

What is the treatment of liver metastases from colorectal cancer?

A

Resect with ≥1 cm margins and administer chemotherapy if feasible

43
Q

What is the surveillance regimen?

A
  • Physical exam
  • stool guaiac
  • CBC
  • CEA
  • LFTs
    • every 3 months for 3 years
    • then every 6 months for 2 years)
  • CXR
    • every 6 months for 2 years
    • and then yearly
  • colonoscopy
    • at years 1 and 3 postoperatively
  • CT scans directed by exam
44
Q

Why is follow-up so important the first 3 postoperative years?

A

≈90% of colorectal recurrences are within 3 years of surgery

45
Q

What are the most common causes of colonic obstruction in the adult population?

A
  • Colon cancer
  • diverticular disease
  • colonic volvulus
46
Q

What is the 5-year survival rate after liver resection with clean margins for colon cancer liver metastasis?

A

≈33% (28% to 50%)

47
Q

What is the 5-year survival rate after diagnosis of unresectable colon cancer liver metastasis?

A

0%

Surgical Recall (168 decks)

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