Colorectal carcinoma (General Surgery EOR - Smarty PANCE)

Define colorectal cancer?

Adenocarcinoma of the colon or rectum

What is the incidence of colorectal cancer?

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

How common is colorectal cancer as a cause of cancer deaths?

Second most common cause of cancer deaths

What is the lifetime risk of colorectal cancer?

6%

What is the male to female ratio of colorectal cancer?

1:1

What are the risk factors for colorectal cancer?

Dietary: Low-fiber, high-fat diets correlate with increased rates

Genetic: Family history is important when taking history FAP, Lynch's syndrome

IBD: Ulcerative colitis Crohn's disease, age, previous colon cancer

What is Lynch's syndrome?

HNPCC: Hereditary NonPolyposis Colon Cancer—autosomal-dominant inheritance of high risk for development of colon cancer

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

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

Colonoscopy q 10 yrs

Double contrast barium enema (DCBE) q 5 yrs

Flex sigmoidoscopy q 5 yrs

CT colonography q 5 yrs

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

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

What percentage of adults will have a guaiac-positive stool test?

2%

What percentage of patients with a guaiac-positive stool test will have colon cancer?

10%

What signs/symptoms are associated with the following conditions: Right-sided lesions? Left-sided lesions?

Right-sided lesions: 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

Left-sided lesions: Left side of bowel has a 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

From which site is melena more common?

Right-sided colon cancer

From which site is hematochezia more common?

Left-sided colon cancer

What is the incidence of rectal cancer?

Comprises 20% to 30% of all colorectal cancer

What are the signs/ symptoms of rectal cancer?

Most common symptom is hematochezia (passage of red blood stool) or mucus; also tenesmus, feeling of incomplete evacuation of stool (because of the mass), and rectal mass

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

Adenocarcinoma, carcinoid tumor, lipoma, liposarcoma, leiomyoma, leiomyosarcoma, lymphoma, diverticular disease, ulcerative colitis, Crohn's disease, polyps

Which diagnostic tests are helpful?

History and physical exam (Note: 10% of cancers are palpable on rectal exam), hemoccult, CBC, barium enema, colonoscopy

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

Colon cancer

What tests help find metastases?

CXR (lung metastases), LFTs (liver metastases), abdominal CT (liver metastases), other tests based on history and physical exam (e.g., head CT for left arm weakness looking for brain metastasis)

What is the preoperative workup for colorectal cancer?

History, physical exam, LFTs, CEA, CBC, Chem 10, PT/PTT, type and cross 2 u PRBCs, CXR, U/A, abdominopelvic CT

What are the means by which the cancer spreads?

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 Transperitoneal Intraluminal

Is CEA useful?

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

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

Endorectal ultrasound (probe is placed transanally and depth of invasion and nodes are evaluated)

How are tumors staged?

TMN staging system

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

20%

Define the preoperative "bowel prep."

Preoperative preparation for colon/rectal resection: 1. Golytely colonic lavage or Fleets Phospho-Soda until clear effluent per rectum 2. PO antibiotics (1 gm neomycin and 1 gm erythromycin 3 doses) Note: Patient should also receive preoperative and 24-hr IV antibiotics

What are the common preoperative IV antibiotics?

Cefoxitin (Mefoxin®), carbapenem

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

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

What are the treatment options?

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

What do all rectal cancer operations include?

Total mesorectal excision—remove the rectal mesentery, including the lymph nodes (LNs)

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

Liver

What is the surveillance regimen?

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

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

90% of colorectal recurrences are within 3 years of surgery

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

Colon cancer, diverticular disease, colonic volvulus

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

33% (28%-50%)

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

0%