Colorectal cancer

Question 1

How does colorectal cancer develop?

Answer 1

colon cells develop in the crypts of Lieberkuhn, which are located in the mucosal layer of the lumen. Damage to these disrupts normal cell formation and causes inflammation and hyperproliferation that may transform into an adenoma (pre-cancerous polyp)

Question 2

Explain the role of secretion in the GI tract

Answer 2

bicarbonate is secreted into the bowel in exchange for chloride.

Question 3

What is the difference between slow mixing and mass peristalsis in the GI tract?

Answer 3

SLOW MIXING: ensures that all the chyme is exposed to the mucosa, where active absorption of sodium and chloride causes water absorption, and constipation
MASS: quicker process, meaning less water absorption, causing Diarrhea.

Question 4

How are hemorrhoids caused?

Answer 4

the rectum has transverse and vertical folds of tissue, each of which contain an artery and a vein. Increased straining pressure can cause distension of these vessels, causing hemorrhoids.

Question 5

Colorectal cancer is the __________ most common type of cancer and the _________ most frequent cause of cancer related death.

Answer 5

THIRD

SECOND

Question 6

What is the most common type of bowel cancer?

Answer 6

adenocarcinomas – initial involvement of the superficial mucosal epithelial cells.

Question 7

What does squamous cell carcinoma of the colon indicate?

Answer 7

this is much more rare than adenocarcinomas, indicating chronic adaptive cellular changes have occurred and this may be due to repeated exposure to carcinogens.

Question 8

What specific type of polyp (adenoma) is associated with an increased malignacy risk and increased mortality? Why?

Answer 8

Villous adenomas– they produce excessive mucus and lead to severe fluid and electrolyte disorders

Question 9

What stage 0 colorectal cancer? What is the treatment?

Answer 9

this is known as carcinoma insitu, meaning that the cancer is located in the mucosal lining of the colon or rectum but has not yet invaded the tissue. This is what occurs with a polyp/adenoma. The appropriate treatment is removal of the polyp.

Question 10

What is Familial adenomatous polyposis (FAP)? What types of cancer does this put you at risk for?

Answer 10

an inherited condition caused by a mutation in the APC gene, in which numerous adenomatous polyps form mainly in the epithelium of the large intestine. For a diagnosis, one must have >100 polyps.

• 100% lifetime risk for CRC
• brain, upper GI, thyroid cancer as well

Question 11

If your patient presented with pigmented lesions on his retina, what might you suspect?

Answer 11

Familial adenomatous polyposis, which is associated with a 100% lifetime risk of developing colorectal cancer

Question 12

What is hereditary non-polyposis colorectal cancer? What other types of cancer would an individual with HNPCC be predisposed to?

Answer 12

cancer in the colon/rectum was not preceeded by the presence of polyps.
-increased risk for endometrial, ovarian, and stomach cancer

Question 13

Explain the 3 stages of clinical trials

Answer 13

1. determine safety and dose of a new treatment in a small group of people
2. provide more detail about the safety of the new treatment and determine how well it works for treating a given form of cancer
3. take a new treatment that has shown promising results when used to treat a small number of patients with cancer and compare it with the current, standard treatment for that disease; phase III trials involve a large number of patients