Colorectal Cancer

Question 1

Colorectal CA Definition

Answer 1

A malignant neoplasm arising from the lumen of the colon, rectum, or anus

Question 2

MC Histology

Answer 2

Adenocarcinoma-begins as non-cancerous adenomatous polyp

Polyps increase with age and are more likely to progress to cancer if have a higher grade of dysplasia

Question 3

Factors that allow for effective screening

Answer 3

Majority of adenomatous polyps do not progress to CA

Progression to CA generally takes 8-10yrs (time b/w screenings)

Incidence greatly increases at 50 (why we begin screening at age 50)

Question 4

Epidemiology of CRC

Answer 4

3rd most common CA

2nd leading cause of cancer death

Generally are left sided, but right sided are becoming more common (colonoscopy better than sigmoidoscopy now)

Patterns of who gets CRC: Sporadic (70%), Familial (25%), Inherited (<10%)

Question 5

Risk Factors for CRC

(modifiable and non-modifiable)

Answer 5

**Modifiable: **

• Obesity (Greater BMI=Great CA Risk)
• Physical Inactivity
• Smoking
• High Red Meat Consumption

Non-Modifiable

• Advanced Age
• Personal Hx of CRC or adenomatous polyps
• Genetics (FAP or Lynch)
• One or more first degree relatives with CRC or polyps
• Two or more second degree relatives with CRC
• Longstanding (>10yrs) IBD
• Hx of endometrial or ovarian CA

Question 6

Sxs of CRC

Answer 6

Most CRC is asymptomatic until advanced

GI blood loss is MC sx:

• occult blood, hematochezia, unexplained anemia

Abdominal pain (bowel obstruction or invasion to other tissues)

Change in bowel movements or caliber of stool

Unexplained anorexia or weight loss

May have back pain from tumor pressing on nerves–sciatic or obturator neuropathic pain syndrome

Question 7

CRC PE Elements to Include

Answer 7

Weight

Signs of anemia (pallor)

Abdominal Exam

Rectal Exam

Question 8

Diagnosis of CRC

Answer 8

Best is Colonoscopy

Sigmoidoscopy can be performed, but only 50% of CAs are L sided

Question 9

Sites of Metastasis Common in CRC and Symptoms

Answer 9

Sites:

• Regional Lymph Nodes
• Liver
• Lungs
• Peritoneum

Symptoms of Metastasis

• RUQ pain
• Abdominal distention
• Early satiety
• Supraclavicular adenopathy
• Periumbilical nodules

Question 10

Staging for CRC (Duke’s CA Staging)

Answer 10

TNM

Tumor invasion

Lymph Node involvement

Metastasis to distant sites (IV)

Stage III and IV have significantly poorer prognosises than I and II

Question 11

Treatment of CRC

Answer 11

Surgery

Radiation

Chemotherapy

Question 12

Labs for Monitoring Dz Progression

Answer 12

CEA–Carcinoembryonic antigen (glycoprotein involved in cell adhesion)

Used preoperatively to aid in staging, surgery and prognosis

Used to monitor dz and success of tx (i.e. should be lower post-op)

Question 13

Screening for CRC

Answer 13

Relatively safe and cost effective

Lab: Fecal Immunochemical Testing (FIT)--Can detect CA’s that bleed, but can’t tx

Structural Exams:

Colonoscopy

• Risks–bowel perf, bleeding, infx, diverticulitis (low compared to benefit)
• CT Colonography: *
• Non-invasive and good visualization
• Same prep, and if positive f/u with coloscopy

Question 14

Adenomatous Polyps

Answer 14

Anatomy:

• Pedunculated: attached by narrow base and a long stalk
• Sessile: broad, flat base with no stalk
• Flat: difficult to detect, more likely to contain dysplastic changes or cancers

Histological findings:

• Tubular: composed of tubular glands extending downward from the outer surface of the polyp (MC)
• Villous: fingerlike epithelial projections extending outward from the surface of the bowel mucosa
• Tubulovillous–both

Villous are more likely to contain invasive carcinoma

Large polyps are more likely to contain invasive carcinoma