EXAM #3: COLORECTAL CANCER

Question 1

What are the landmarks for the colon?

Answer 1

1) Tenia coli

2) Transition from colon to rectum where the Tenia coli “splay”

Question 2

What are the major arteries that branch from the SMA to the colon?

Answer 2

SMA supplies proximal 2/3 of the colon–branches include:

1) Ileocolic
2) Right colic
3) Middle colic

Question 3

What are the major arteries that branch from the IMA to the colon?

Answer 3

IMA supplies the distal 1/3 of the colin–branches include:

1) Left colic
2) Sigmoidal branches
3) Superior rectal

Question 4

What arteries supply the rectum? Where do these arteries branch from?

Answer 4

1) Superior rectal from the IMA

2) Middle and inferior rectal from the internal iliac arteries

Question 5

Review the layers of the GI mucosa.

Answer 5

1) Mucosa
- Epithelium
- Lamina propria
- Musclaris mucosa
2) Submucosa
3) Muscularis Propria
4) Serosa

Question 6

How prevalent is colon cancer?

Answer 6

3rd most common cancer

Question 7

List the risk factors for colon cancer.

Answer 7

1) Family history
2) IBD
3) Smoking
4) Alcohol
5) Obesity
6) Inactivity
7) Diet rich in red meat and animal fat

Question 8

What factors are protective against colon cancer?

Answer 8

1) Hormone Replacement Therapy
2) NSAIDs
3) Diet rich in fiber, fruits, and veggies

Question 9

Outline the Adenoma-Carcinoma Sequence.

Answer 9

1) APC= early adenoma
2) K-RAS= intermediate adenoma
3) DCC= late adenoma
4) p53= carcinoma

*Note that this normally takes roughly 10 years.

Question 10

How can adenomatous polyps be removed via colonoscopy?

Answer 10

Snare excision

Question 11

What are the four most common etiologies of colon cancer?

Answer 11

1) Sporadic
2) Non-syndromic familial colorectal cancer
3) FAP
4) HNPCC or Lynch Syndrome

Question 12

What mutation is associated with FAP?

Answer 12

Autosomal dominant APC mutation

Chromosome 5

Question 13

What is the clinical manifestation of FAP?

Answer 13

1,000 of adenomatous polyps

• Early onset
• WILL get colon cancer

Question 14

What is the treatment for FAP?

Answer 14

Total colectomy

Question 15

What genetic defect is seen in HNPCC?

Answer 15

Defects in DNA mismatch repair genes

Question 16

What are the clinical manifestations of HNPCC?

Answer 16

• 100s of polyps
• Accelerated progression to colon cancer

*Not a 100% progression to cancer like APC.

Question 17

What cancers are associated with HNPCC in addition to colon cancer?

Answer 17

Endometrial

Ovarian

Question 18

What is the treatment for HNPCC?

Answer 18

Colectomy

Question 19

What sign is associated with advanced polyps?

Answer 19

Fecal occult blood test

Question 20

What are the three major screening modalities for colorectal cancer?

Answer 20

1) Colonoscopy*
2) Flexilble sigoidoscopy
3) FOBT (Fecal Occult Blood Test)

*Gold standard

Question 21

What imaging modalities are used to screen for colorectal cancer?

Answer 21

1) Double contrast barium enema

2) CT Colongraphy

Question 22

What is the difference between colonscopy and flexible sigmoidoscopy?

Answer 22

Flexible sigmoidoscopy isn’t as long (will only reach the splenic flexure)

*Note that you develop more polyps in the distal colon/rectum, which is why this is used as a good alternative to colonoscopy

Question 23

What is the drawback to the fecal occult blood tests?

Answer 23

Detects more ADVANCED polyps or cancer

Question 24

What are the drawbacks to double contrast barium enemas?

Answer 24

1) Still requires bowel prep
2) Give rectal air and contrast
3) Only detects advanced polyps

Plus, if its positive, you still have to get a colonoscopy.

Question 25

What are the drawbacks to CT Colonography?

Answer 25

Same as barium enema.

Question 26

What are the screening recommendations for colorectal cancer?

Answer 26

1) Colonoscopy every 10 years 2) Flexible sigmoidoscopy every 5 years AND FOBT every 3 years 3) FOBT every year

Question 27

When do you start screening?

Answer 27

If AVERAGE risk, start at 50 y/o *Average= no family history or personal history of polyps/cancer

Question 28

What gives a patient a positive family history of colon cancer?

Answer 28

1) First degree relative with hx at less than 60 2) 2x first degree at ANY age 3) Second degree relative less than 50

Question 29

When do you start screening for patients with a family history of colon cancer?

Answer 29

40 y/o AND repeat every 5 years

Question 30

What are the screening recommendations for colon cancer in patients with IBD?

Answer 30

1) Start colonoscopy 8-10 years after onset of sx. 2) Collect 4x random biopsies every 10cm (total of 30+) *Repeat every 1-2 years

Question 31

When do you start screening for colon cancer in HNPCC?

Answer 31

Age 20-25 y/o *Repeat every 1-2 years

Question 32

What are the screening recommendations for FAP?

Answer 32

Age 10-12 y/o *Repeat every 1-2 years

Question 33

What is the most common cause of colon obstruction in adults?

Answer 33

Colorectal cancer

Question 34

What symptoms are associated with colorectal cancer?

Answer 34

- Vague abdominal pain - Change in bowel habits e.g. pencil-thin stool - GI Bleeding

Question 35

For a person that presents with symptoms suggestive of colon cancer, what imaging should be ordered?

Answer 35

1) KUB 2) CT abdomen and pelvis with IV and enteral contrast 3) Colonoscopy or Proctoscopy - TATTOO the lesion!

Question 36

What is the serum tumor marker for colon cancer? How is this used?

Answer 36

CEA= carcinoembryonic antigen *Clinically this is used for surveillance s/p resection

Question 37

What is the TNM classification system?

Answer 37

T= invasion depth of Tumor N= extent of regional lymph Node involvement M= Metastasis

Question 38

Outline the different T-stages of tumors.

Answer 38

``` Tis= intraepithelial T1= Submucosa T2= Muscularis propria T3= Pericolorectal tissue T4a= Penetrates peritoneum T4b= invading adjacent organs ```

Question 39

Outline the N-stages.

Answer 39

``` N0= no nodes N1= 1-3 regional nodes N2= 4+ nodes ```

Question 40

How many nodes need to be examined for adequate staging?

Answer 40

At least 15 nodes

Question 41

Outline the M-stages.

Answer 41

``` M0= no mets M1= distant mets ```

Question 42

What resection margins do you need to have in the treatment of colon cancer?

Answer 42

5cm | 1-2cm in the rectum

Question 43

What determines your resection margin in the treatment of colon cancer?

Answer 43

The resected artery *All bowel associated with artery needs to be removed

Question 44

What is a Low Anterior Resection (LAR)?

Answer 44

Rectosigmoid resection below the peritoneal reflection *This procedure preserves the anal sphincter and opening

Question 45

What is an Abdominal Perineal Resection (APR)?

Answer 45

Rectosigmoid resection including: - Anal sphincters - Anal opening

Question 46

When does colon cancer require the addition of chemotherapy to surgical resection?

Answer 46

1) Any nodal disease | 2) Some T3 and any T4+ disease

Question 47

What colon cancer mets are treated with resection?

Answer 47

Liver and lung metastases

Question 48

What colon cancers are treated primary with chemotherapy and secondarily with palliative resection?

Answer 48

1) Bleeding 2) Obstruction 3) Perforation

Question 49

What is the treatment for Tis and T1 rectal cancer?

Answer 49

Transanal excision

Question 50

What is the treatment for T2 rectal cancer?

Answer 50

Surgical resection

Question 51

What is the treatment for T3, T4, or N+ rectal cancer?

Answer 51

1) Neoadjuvant (i.e. begin with) chemoradiation | 2) Surgical resection

Question 52

After surgical resection, what are the recommendations for surveillance?

Answer 52

1) H and P every 3-6 months for 5 years 2) CEA same 3) CT annually for 5 years