Colorectal CA Flashcards
Colorectal CA is the _____ leading cause of cancer mortality for ____ and third leading cause for ________ in ______
second
males
females
Canada
Etiology/Risks (7)
- idiopathic
- aging
- familial predisposition
- IBD
- Adenomatous polyposis
- Poor diet
- Protective role of aspirin?
Etiology: What is Idiopathic?
The cause is largely unknown and carcinogens are idiopathic .
Etiology: 90% of persons who dev Colorectal CA are older than ____ years of age. Why?
Most colorectal CA occur after 50 y/o.
d/t accum. exposure to carcinogens
Etiology: those who have two or more _____ or _____-degree _____ with colorectal CA make up ____% of all persons who have it (familial predisposition)
- first
- second
- relatives
- 20%
Etiology: What two conditions have higher incidence of colorectal CA?
- Crohn’s disease
2. Ulcerative Colitis
Etiology: What is adenomatous polyposis? Adeno-?
A disorder with abundance of polyps projecting into the lumen of the large bowel.
Greater risk of dev Colorectal CA.
Adeno= meaning granular epithelial cells
Etiology: What diet contribute to Colorectal CA?
Diet is not well balanced –>there is high fat content and refined sugar intake in diet.
How does high fat content lead to Colorectal CA?
Fat is emulsified and broken down by bile.
Fat in diet increase synthesis of bile acids in liver which may be converted to potential carcinogens by bacterial flora in colon.
Normal flora in gut converts bile acid to carcinogens ( a chemical product of the processing)
How does refined CHO (sugar) contribute to Colorectal CA?
Refined CHO nourishes bacteria and promote bacteria proliferation
Etiology: How does aspirin protect colorectal CA? Role of Prostaglandins. What does COX2 do?
Prostaglandins mediate pain during inflm and promote cell proliferation and trigger formation of tumors.
COX 2 (cyclooxygenase) enzyme converts arachidonic acid to prostaglandins.
Aspirin inhibits cyclooxygenase (COX2) which catalyzes the conversion of arachidonic acid in cell membrane to prostaglandins.
Regular ASA use appears to reduce the risk of colorectal CA that overexpresses COX2
Patho: How many stages is in Colorectal CA? Are they progressive and how is it staged?
- 4
- yes
- global staging levels of tumors
Stage I of Colorectal CA (What tissue layer is impacted? survival rate? %?)
Stage I is limited to the mucosa and submucosa layer of colon.
If detected in stage I, there is a 5 year survival rate of 90-100%.
Stage II (tissue layer impacted? lymph nodes involvement?survival rate? %?
There is infiltration in the muscularis externa (mucosa and submucosa layers still affected)
No lymph node involvement yet.
5 year survival rate of 70-85%
Stage III: tissue layer impacted? lymph nodes involvement?survival rate? %?
All layers previously + serosa.
Lymph nodes positive –> malignant cells spread to lymph nodes
5 year survival rate is 40-60%
Stage IV: tissue layer impacted? lymph nodes involvement? survival rate? ________ is present
Metastatic tumor penetrates the serosa and adjacent organs
Much poorer prognosis.
Seeding
Manifestations (4): Late or early onset?
usually late onset
- hemorrhage (early): frank blood in stool is a relatively early sign
- alternate bowel habits, diarrhea, and constipation: nonspecific
- pain: is severe and late sign
Diagnosis (4)
- DRE: digital rectal exam
- fecal occult blood (screen)
- barium enema
- sigmoidoscopy, and colonoscopy
What is DRE? Is it routine (age?)?
rectum and colon is palpated with finer to determine lumps and change in consistency
Routine physical exam after age 50
What is fecal occult blood screening? What does it test for? Routine?
stool sample is collected and put onto a test strip to be sent to a lab to tests for occult blood
routine physical exam after age 50
What is barium enema? When is it done?
Barium is introduced in rectum and x-ray is taken to visualize the malignancy
When screens are positives
What is sigmoidoscopy? when is it done?
to examine the rectum and sigmoid colon with a hollow lighted tube that is inserted thru the rectum
When screens are positives
What is colonoscopy? when is it done?
to examine the entire bowel ending at the cecum
When screens are positives
What can be done during the scope?
removal of polyps and tissue can be obtained for biopsy
treatment ( 3)
- sx
- preoperative radiation to shrink tumor
- postoperative chemotherapy used w/ radiation
In palliative treatment what is used?
radiation and chemo `
What tx in some cases demonstrate increase 5 year survival rate?
preoperative radiation
What is the only curative approach and is shown to be quite successful?
Sx
