COLON CANCER (TB) Flashcards
Which malignancy is increasingly seen in younger patients
and why is early screening important?
What is the second leading cause of cancer death in the United States?
Colorectal cancer (second to lung cancer).
What trend is observed in colorectal cancer incidence among individuals under 50 without family history?
Incidence has risen by 2% each year.
Why do younger colorectal cancer patients tend to present with more advanced disease?
They often dismiss symptoms like hematochezia
What is the rank of colorectal cancer in terms of incidence across all age groups?
Third (1st: Breast
What is the second leading cause of cancer death in both sexes across all age groups?
Colorectal cancer.
What type of polyps are the most common precursor to colorectal cancer?
Adenomatous polyps.
Do most polyps cause symptoms?
No
What percentage of middle-aged individuals have adenomatous polyps?
About 30%.
What percentage of elderly individuals have adenomatous polyps?
About 50%.
What percentage of polyps become malignant?
Less than 1%.
Why does a negative FOBT not rule out polyps?
Bleeding from polyps is intermittent.
What increases the risk of malignancy in a polyp?
Polyp size.
What genetic mutation is associated with colorectal cancer in the K-ras gene?
Point mutation in K-ras proto-oncogene.
What genetic alteration involves the APC gene in colorectal cancer?
Allelic loss at 5q21.
What gene on chromosome 18q is frequently lost in colorectal cancer?
DCC gene (Deleted in Colorectal Cancer gene).
What gene mutation on chromosome 17p is associated with colorectal cancer?
p53 tumor suppressor gene mutation.
What is the adenoma to carcinoma sequence?
A progression from normal epithelium to hyperproliferation
What are the two major types of polyps?
Pedunculated (with stalk) and Sessile (directly attached).
What are the histologic classifications of adenomatous polyps?
Tubular
Which type of adenomatous polyp has the highest malignancy potential?
Villous adenomas.
What is the malignancy risk for a polyp <1.5 cm?
Less than 2%.
What is the malignancy risk for a polyp 1.5-2.5 cm?
2-10%.
What is the malignancy risk for a polyp >2.5 cm?
About 10%.