Colorectal Cancer: Screening, Diagnosis, and Treatment

Question 1

Updated USPSTF guidelines?

Answer 1

Adults 45-75 years

• screening for colon cancer should be performed in all adults aged 45-75

Adults 76-85

• routine screening should not be performed in people who have previously had consistently normal colon cancer screening exams
• decision to screen after 75 should be an individual decision

Question 2

• looks for blood in the stool
• Guaiac- based test- reacts to heme
• decreases CR mortality by 15-33%
• advantages: done at home, no direct risk to colon, no bowel prep, no sedation
• limitations: may miss polyps (Especially serrated lesions) and some early cancers
• cannot remove polyps, so a colonoscopy is needed if the test is positive
• need to be done years

Answer 2

Fecal occult blood test

Question 3

• same high sensitivity as gFOBT but higher specificity
• reacts to globin (not heme)
• no dietary restrictions

Answer 3

Fecal immunochemical test (FIT)

yearly test

Question 4

• looks for blood and DNA shed from colon polyps and cancers in stools
• advantages: done at home, no direct risk to the colon, no bowel prep, no sedation
• limitations:may miss polyps and some early cancers
• cannot remove polyps, so colonoscopy is needed if the test is positive
• current man. recommendation is to repeat the test every 3 years

Answer 4

Multitarget stool DNA (cologaurd)

Every three years

Question 5

• Looks for polyps and cancers; evaluates the left half of the colon, decreases CRC mortality by 60%
• advantages: does not require a full bowl preparation, sedation is not necessary
• limitations: views 1/3rd of the colon, cannot remove all polyps, so a colonoscopy is needed if the test is abnormal
• can be uncomfortable if no sedation is used
• very small risks of bleeding and perforation

Answer 5

Flexible sigmoidoscopy

Question 6

• Studies in average-risk screening patients have shown sensitivites of 90-94% for polyps > 1 cm
• sensitivities for adenomas 6-9mm range from 73-98%
• do not report polyps < 5mm
• advantages: procedure takes about 10 minutes, no sedation needed, visualizes the entire colon, do not need to stop anticoagulation
• limitations: full bowel preparation is needed, can miss small polyps, cannot remove polyps, so a colonoscopy is need if the test is abnormal, extra-colonic finding may result in unnecessary imaging

Answer 6

CT colonography

Question 7

advantages:

• visualizes the entire colon; polyps can be removed and or biopsied during this procedure
• other diseases of the colon can be diagnosed at the same time
• if normal, you do not need another exam for 10 years

Limitations

• full bowel preparation is needed
• cannont miss small polyps
• sedation is usually needed- driver, time off from work
• very small risks of bleeding and perforation

Answer 7

Colonoscopy

Question 8

magnitude of risk for familial colorectal cancer is increased by?

Answer 8

• age of the individual at risk
• age at diagnosis of the affected relative
• degree of relation between teh individual and the affected relatives
• number of affected relatives

Question 9

Common presenting signs and symptoms of colon cancer

Answer 9

• Occult blood in stool or bright red per rectum
• iron deficiency anemia
• change in caliber of stools
• constipation or diarrhea
• unexplained weight loss

Question 10

• localized to mucosa and submucosa

Answer 10

AJCC stage 1

Question 11

into or through the muscle w/o nodes

Answer 11

AJCC stage II

Question 12

positive nodes

Answer 12

AJCC stage III

Question 13

distant metastases present

Answer 13

AJCC stage IV

Question 14

What to do after diagnosis of CRC?

Answer 14

• CT chest/abdomen/pelvis with IV contrast
• rectal ultrasound or pelvic MRI for rectal cancer staging
• CEA level (serum tumor marker)
• colorectal surgery consults
• oncology consults

Question 15

Treatment of localized colon cancer

Answer 15

Localized disease

• primary treatment is surgey
• remove tumor with adequate margins
• colon- hemicolectomy
• rectal- low anterior resection or abdominoperineal resection

Question 16

treatment of metastatic disease to nodes only

Answer 16

• Surgy plus chemotherapy for colon CA
• neodjuvant (before surgery) chemo/radiation for rectal CA
• risks of chemo (5FU, oxaliplatin, leucovorin): fatigue, neutropenia, nausea/vomiting, diarrhea, mucositis, cold-induced neuropathy

Question 17

Surveillance after diagnosis of colorectal cancer

Answer 17

• labs: CEA every 3-6 months for the first 5 years
• imaging: CT scan yearly for 5 years

Colonoscopies

• pre-or perioperative documentation of entire colon
• then 1 year post-treatment
• if normal, repeat in 3 years
• if normal, repeat in 5 years and continue every 5 years

Question 18

• autosomal dominant germline mutation in DNA mistmatch repair genes (MLH1, MSH2, MSH6, PMS2, EPCAM)
• abnormal DNA mismatch repair leads to microsatellite instability (MSI)
• MSI is in 90% of lynch crc
• Germline mutations mean that MSI can also be seen in other tissues (e.g, uterine CA)
• amsterdam criteris: 3 or more relatives with verified CRC in family; involves 2 or more generations; 1 or more cancers diagnosed before the age of 50)

Answer 18

Lynch syndrome

Question 19

Surveillance recommendations for lynch syndrome

Answer 19

• Colonoscopy q1-2 years beginning at age 25 or 10 years earlier than youngest affected relative
• total or subtotal colectomy for pts with CRC or advanced adenoma
• annual pelvic exam +/- transvaginal US starting at age 30-35 or 5 years earliers than youngest case; prophylactic hysterectomy and ooophorectomy after childbearing years
• Annual UA starting at 25