Colorectal Cancer

Question 1

What are risk factors for colorectal cancers?

Answer 1

Diet
● Lower incidence with high fibre and low animal fat diet
● Fat and meat alter [ ] of cholesterol and fecal bile salts, and change intestinal
flora → damages mucosa → increases proliferative activity
● Decreased fibre carcinogenic promoter b/c increases contact time b/t carcinogen
and mucosa → increased mutations in bowel wall
● Increased alcohol and caffeine may increase risk
● Charbroiled and fried foods are carcinogenic
● Deficiencies in vitamins A, C & E, selenium, and Ca may be risk
● Genetic factors
● First degree relatives with colorectal cancer gives 3x risk
● Genetic syndromes: familial adenomatous polyposis (FAP), hereditary
nonpolyposis colorectal cancer (HNPCC) increase risk
● Other factors
● Inflammatory bowel disorders (Crohns, ulcerative colitis) – associated with
dysplasia and malignant lesions
● Polyps – polyposis adenomas, villous adenomas
● Aging – >50 is a risk factor
● History of breast, endometrial and ovarian cancer

Question 2

How is CRC screened & detected?

Answer 2

For asymptomatic pt
● Annual digital rectal exam for >50yo
● Annual fecal occult blood test (FOBT) for >50yo
● Proctosigmoidoscopy q 5yrs
● Colonoscopy q10yrs
● High risk pts may need earlier and more frequently (see pg. 126 table)
● Most tumors found in lower rectum (up to 7cm), so abdo and digital rectal exams
(DREs) should be performed annually, and before scopes
● FOBT
● Effective, inexpensive to examine for hidden blood in stool
● False –ves: 50% polyps aren’t bleeding when sample collected
● False +ves: red meats, foods with peroxidase (citrus, tomatoes, turnips, beets,
radishes, cherries, horseradish), certain medications , hemorrhoids,
diverticulosis,
● Need high residue and no meat diet for 3 days prior to encourage bleeding from
small colonic lesions and prevent false +ves
● Double contrast barium enema – q5-10 yrs; complements a colonoscopy
● Sigmoidoscopy – q10yrs; screens cancerous lesions in colon and rectum
● Colonoscopy – q10yrs; complete visualization of colon; most accurate measure

Question 3

How is CRC classified?

Answer 3

● 35% of lesions occur in sigmoid colon
● 98% are adenocarcinomas and are moderate to well-differentiated cancers
● Others: epithelioma, squamous cell carcinoma, sarcoma, lymphoma, leiomyosarcoma,
melanoma
● Cancer of anus rare

Question 4

What are the clinical features of CRC?

Answer 4

● General: change in bowel habits, blood in stool, abdo pain, anorexia, flatulence,
indigestion
● Late symptoms: weight loss, fatigue, decline in general health
● Right-sided lesions: no changes in bowel habits b/c liquid stool, dull vague abdo pain
radiating to the back, palpable masses in RLQ, dark red or mahogany red blood in
stools, weakness, anemia, malaise, indigestion, weight loss
● Left-sided lesions: change in bowel habits, cramps, gas pains, decrease in caliber of
stool, bright red bleeding, constipation, rectal pressure, incomplete evacuation, abdo
pain
● Transverse colon: palpable masses, obstruction, changes in bowel habits, bloody stools
● Rectal: changes in bowel habits, bright red bleeding, tenesmus, pain in groin, labia,
scrotum, legs or penis, constipation
● Pain may be the last symptom to occur, and mets may be present before treatment
sought

Question 5

How is CRC diagnosed?

Answer 5

● High risk or symptomatic pts require further testing
● Barium enema – detects small tumors
● Colonoscopy after enema if surgery indicated – able to biopsy lesions
● CXR, CT, MRI, PET, U/S for mets
● CBC, lytes, AST, BUN, LDH, SGOT, ALP, CEA, LASA, CA 19-19, DNA ploidy, K-ras, p53
● Diagnosis confirmed by tissue biopsy of suspected site

Question 6

How is CRC staged?

Answer 6

● Duke’s classification, TMN (See pg. 129 table)
● Size of tumor not a factor – depth of tumor penetration is the best indicator of prognosis
● Stage 0-2: T1-4, N0, M0
● Stage 3: T1-4, N1-3, M0
● Stage 4: T1-4, N1-3, M1

Question 7

What are the disease complications of CRC?

Answer 7

• bowel perforation
• obstruction of surrounding GU organs
• hemorrhage
• liver failure
• distant mets - brain, bone, lung, adrenal glands

Question 8

How is surgery used to treat CRC?

Answer 8

● Local – polyps excision during sigmoidoscopy or colonoscopy
● Surgical goal: colon resection and disease free margins
● Tumor, vessels and lymph resected to prevent seeding
● Size, location and mets determine surgery

● 3 major surgeries:
■ Colon resection and reanastomosis
■ Colostomy (temp or perm)
■ Abdominoperineal resection – can result in sexual dysfunction in men,
greatest risk of infection

Question 9

What are important pre-op nursing considerations in CRC?

Answer 9

● Pre-op – 2-3 day liquid diet, laxatives, enemas, oral Abx, teaching, support

Question 10

What are important post-op nursing considerations in CRC?

Answer 10

● Post-op – assessment, NG/foley care, stoma site (if black, blue or dusky means
ischemia), drainage should be scant, blood tinged; deep breathing, coughing,
early ambulation and pain control encouraged, NPO
● Complications: infection, thrombophlebitis, paralytic ileus (increased abdo girth,
distension, N&V), PE, hemorrhage, anastomotic leaks (common in lower
resections, can cause fistulas)

Question 11

How is radiation used to treat CRC?

Answer 11

● Based on disease and prognostic factors
● Alone or combo with chemo to reduce tumor border and local recurrence
● Adjuvant – reduces tumor burden, increased resectability, eradicate remaining
cells to reduce local recurrence
● Pre-op rads – reduce tumor load and seeding, preserves sphincter
● Post-op rads – effective in rectal cancer for palliation of pain, bleeding, local mets

Question 12

What are the complications of treating CRC with RT?

Answer 12

■ Skin irritation
■ N&V – d/t destruction of epithelial lining of bowel wall; anti-emetics pre
and post rads; small frequent meals; high protein and liquid supplements
■ Diarrhea – 1-2 weeks after rads; rapid proliferation of epithelial cells; low
residue, high carbs, high protein, high potassium; avoid milk products
■ Cystitis – rads can inflame bladder; burning, back pain, hematuria, foul
smelling urine; increase fluid intake and limit caffeine
■ Sexual dysfunction
■ Myelosuppression
■ Fatigue

Question 13

How is chemotherapy used to treat CRC?

Answer 13

● Important role in stage III and IV
● Adjuvant therapy
■ 5-FU and leucovorin for stage II and III
■ FOLFOX-4 – oxaliplatin, 5-FU, leucovorin (q2weeks for 6 mos)
● Metastatic disease
■ IFL – irinotecan, 5-FU, leucovorin → causes severe diarrhea
■ FOLFIRI – irinotecan, 5-FU
■ Capiri – irinotecan, capecitabine → causes diarrhea and hand-foot
syndrome
■ FOLFOX-4 – oxalplatin, 5-FU, leucovorin → causes peripheral
neuropathy
■ Capox – capecitabine, oxalplatin

Question 14

How is targeted therapy used to treat CRC?

Answer 14

EGFR (epidermal growth factor receptor) – can cause aggressive tumors, poor
prognosis, shorter survival
● Cetuximab (Erbitux) +/- irinotecan – increased anti-tumor effect
● Bevacizumab (Avastin) – anti-vascular endothelial growth factor monoclonal
antibody
■ Avastin + 5-FU for metastatic cancer