SM_165: Colorectal Cancer

Question 1

____ is the third most common cancer for men and women and second leading cause of cancer death for men and women

Answer 1

Colorectal cancer is the third most common cancer for men and women and second leading cause of cancer death for men and women

• Highest in North America, Western Europe, Australia, New Zealand
• Decreasing incidence and mortality
• Worse survival in LMICs
• Racial / ethnic disparities

Question 2

Risk factors for colorectal cancer are ____, ____, ____, ____, and ____

Answer 2

Risk factors for colorectal cancer are

• Increasing age: most cases after age 50
• Diet and environment: high fat, low fiber, and obesity
• Family history: risk increases with number of affected family members
• Prior history of colorectal cancer / polyps and large polyps
• IBD: mainly ulcerative colitis

Question 3

Colorectal cancer syndromes include ____ and ____

Answer 3

Colorectal cancer syndromes include familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer (Lynch syndrome)

• Familial risk

Question 4

Most colorectal cancers arise from ____

Answer 4

Most colorectal cancers arise from adenomas following a pathway with several genetic mutations

• Mutations occur at the germline level
• Most sporadic cancers follow a pathway similar to familial adenomatous polyposis

Question 5

Describe the pathogenesis of colorectal cancer

Answer 5

Colorectal cancer pathogenesis

1. Normal colon
2. Small adenoma
3. Large adenoma with villous component
4. Large adenoma with high grade dysplasia
5. Large adenoma with invasive carcinoma

Question 6

Familial adenomatous polyposis is an ____ syndrome caused by a mutation in the ____ gene

Answer 6

Familial adenomatous polyposis is an autosomal dominant syndrome caused by a mutation in the APC (adenomatous polyposis coli) gene

• Classic form characterized by hundreds-thousands of polyps
• Polyps develop early (teens) and lifetime risk of colorectal cancer approaches 100%
• Treatment: subtotal or total colectomy
• Genetic testing useful for diagnosis and screening

Question 7

Lynch syndrome (hereditary nonpolyposis colorectal cancer) is an ____ syndrome caused by a mutation of ____ genes

Answer 7

Lynch syndrome (hereditary nonpolyposis colorectal cancer) is an autosomal dominant syndrome caused by mutation of MMR (mismatch repair) genes

• Few or no polypoid adenomas, tumors may arise from flat or depressed adenomas
• After colorectal cancer diagnosis, treatment usually involves subtotal colectomy
• Generic testing used for diagnosis and screening

Question 8

Lynch syndrome (hereditary nonpolyposis colorectal cancer) also involves ____ malignancy

Answer 8

Lynch syndrome (hereditary nonpolyposis colorectal cancer) also involves extracolonic malignancy

• Hepatobiliary
• Stomach
• Small bowel
• Endometrium
• Uroepithelium
• Ovary
• Keratoacanthomas / sebaceous gland neoplasia (Muir-Torre syndrome

Question 9

Symptoms and signs of colorectal cancer are ____, ____, ____, ____, and ____

Answer 9

Symptoms and signs of colorectal cancer are abdominal / rectal pain, change in bowel movement pattern, hematochezia (blood per rectum), anemia (often of iron deficiency), and weight loss / fatigue / obstruction

Question 10

____ colorectal tumors are less likely to obstruct the lumen and more likely to cause chronic blood loss and presentation with fatigue and anemia

Answer 10

Right side colorectal tumors are less likely to obstruct the lumen and more likely to cause chronic blood loss and presentation with fatigue and anemia

Question 11

____ colorectal tumors may cause obstructive symptoms and present with hematochezia

Answer 11

Left side tumors colorectal tumors may cause obstructive symptoms and present with hematochezia

• Change in bowel movement pattern, pain, or frank obstruction

Question 12

Rectal cancers may present with ____

Answer 12

Rectal cancers may present with local pain

Question 13

Colorectal cancer should be considered especially if ____, ____, ____, or ____

Answer 13

Colorectal cancer should be considered especially if

• Recent onset of symptoms
• Patient older than 40
• FMHx of colorectal cancer or polyps
• Iron deficiency anemia in men or postmenopausal women

Question 14

Evaluation of colorectal cancer involves ____, ____, and ____

Answer 14

Evaluation of colorectal cancer involves colonscopy, flexible sigmoidoscopy, and air contrast barium enema

• Colonscopy: preferred method to evaluate lumen, allows for localization of lesions / biopsy / polyp removal
• Flexible sigmoidoscopy: diagnoses lesions in left side of colon up to splenic flexure
• Air contrast barium enema: useful if colonoscopy not feasible (tortuous sigmoid, stricture, obstructing mass) but not as sensitive for smaller lesion

Question 15

Describe clinical staging of colorectal cancer

Answer 15

Clinical staging of colorectal cancer

• Established by biopsy of colorectal lesions
• Staging required to direct treatment
• Initial staging is clinical (pathological staging requires surgical specimen)
• Usually includes physical exam and CT scan of abdomen and pelvis (to detect local extension, abnormal lymph nodes, and distant metastases), CXR, liver enzymes, carcinoembryonic antigen

Question 18

Rectal cancer is ____ to spread locally and has ____ risk of local recurrence than colon cancer

Answer 18

Rectal cancer is more likely to spread locally and has higher risk of local recurrence than colon cancer

• Need to evaluate preoperatively to determine depth and lymph node involvement
• Endoscopic ultrasound is useful to assess depth of involvement and presence of lymph nodes and allows fine needle aspiration to confirm tumor involvement in suspicious nodes

Question 19

____ staging is used for colorectal cancer

Answer 19

TNM staging is used for colorectal cancer

Question 20

____ is the treatment of choice for the vast majority of colorectal cancers

Answer 20

Surgery is the treatment of choice for the vast majority of colorectal cancers

Question 21

____ is used for adjuvant treatment of patients with colorectal cancer who undergo potentially curative resection but have higher risk of recurrence, such as stage III colon cancer and stage II or III rectal cancers

Answer 21

Chemotherapy is used for adjuvant treatment of patients with colorectal cancer who undergo potentially curative resection but have higher risk of recurrence, such as stage III colon cancer and stage II or III rectal cancers

• 5-FU and leucovorin, w/ or w/o oxaliplatin

Question 22

___ is used to treat stage II or III rectal cancer usually in combination with chemotherapy

Answer 22

Radiotherapy is used to treat stage II or III rectal cancer usually in combination with chemotherapy

• Adjuvant or neoadjuvant therapy as well
• Only used for select colon cancer cases with high risk of local recurrence (e.g. perforation, invasion into adjacent organs)

Question 23

____ can be used to relieve colorectal obstruction

Answer 23

Endoscopic stenting can be used to relieve colorectal obstruction

Question 24

Summarize colorectal cancer treatment

Answer 24

Colorectal cancer treatment

Question 25

Higher stage colorectal cancer is associated with ____ prognosis

Answer 25

Higher stage colorectal cancer is associated with poorer prognosis

Question 26

Goals of colorectal cancer screening are ____ and ____

Answer 26

Goals of colorectal cancer screening are detection of colorectal cancer at early stages to reduce morbidity and mortality and detection and removal of pre-malignant polyps to reduce the incidence of colorectal cancer

Question 27

FOBT/FIT is based on the rationale that ___

Answer 27

FOBT is based on the rationale that most colorectal cancers bleed so large polyps may also bleed

• Does not distinguish between bleeding from cancer / polyps and from other GI lesions
• False positives with certain foods and rare red meets
• False negatives with intermittent or insufficient bleeding, delay of assay, or sampling error

Question 28

Fecal DNA test tests for ____

Answer 28

Fecal DNA test tests for common fecal DNA mutations associated with colorectal neoplasia

Question 29

Positive FOBT leads patients to obtain a ____

Answer 29

Positive FOBT leads patients to obtain a colonoscopy

Question 30

Flexible sigmoidoscopy ____

Answer 30

Flexible sigmoidoscopy detects only about 50-70% of all colorectal cancers and polyps because only left side of colon is examined

• Distal polyps predict proximal polyps / cancer
• Allows direct visualization of bowel mucosa and biopsy of lesions
• If positive, get colonscopy

Question 31

Colonoscopy allows ____ and ____

Answer 31

Colonoscopy allows direct inspection of colorectal mucosa for the entire colon and opportunity for biopsy / removal of lesions (polypectomy)

• Usually need sedation
• Risk of perforation

Question 32

____ is performed after bowel preparation, involves computer enhanced CT scan, and does not allow for biopsy

Answer 32

CT colongraphy is performed after bowel preparation, involves computer enhanced CT scan, and does not allow for biopsy

Question 33

If a capsule colonscopy identifies a lesion, ____ is required

Answer 33

If a capsule colonscopy identifies a lesion, colonscopy is required

• Ingestion of a video capsule and use of the images obtained during passage to detect neoplasia

Question 34

Colorectal cancer screening begins at ____ and ____

Answer 34

Colorectal cancer screening begins at age 45 for African Americans and age 50 for all other races

• Discontinue in ≥ 75 years with prior negative screening, patients whose life expectancy < 10 years, and patients ≥ 85 years without prior screening

Question 35

Screen for colorectal cancer more regularly in people with ____, ____, and ____

Answer 35

Screen for colorectal cancer more regularly in people with history of colorectal cancer / polyps, IBD for >8-10 years, and familial syndromes