Colorectal Cancer Screening Flashcards
Define surveillance
Active search for cancer in patient with a disease or condition putting them at risk for cancer
Define screening
Applying a test to a healthy population to confirm the absence of disease (rule it out)
Requirements for a good screening test
High specificity
High NPV
High sensitivity (for confirmatory tests like colonoscopy)
In what age groups is colorectal cancer a significant cause of cancer-related deaths?
#3 in 30 - 49 #2 in 50 - 69 and 70+
State of worldwide incidence of CRC
Increasing
Incidence of CRC in Canada for men and women
Man = 13.8% (1:13) Women = 11.6% (1:15)
Number of new cases in Canada per year under 25 yo
~25
State of prevalence of CRC and why
Increasing because early detection and treatment = more remain alive
State of CRC incidence in North America and why
Decreasing due to implementation of population-based screening programs
5 facts about CRC in Quebec (2013)
6300 new cases (3500 men, 2800 women)
2450 estimated deaths (1300 men, 1500 women)
2nd highest killer in men (after lungs)
3rd highest killer in women (after lung, breast)
2nd highest in Canada (since 8M population)
Adenoma to carcinoma sequence
Normal –> Proliferative epithelium –> Adenoma –> Carcinoma
What causes the progression of normal epithelium to carcinoma
Series of accumulating genetic alterations over years
First gene to be hit by mutations in CRC
APC (adenomatous polyposis coli)
2 pathways to CRC
Chromosomal instability Microsatellite instability (MMR genes)
Most common pathway to CRC
Chromosomal instability (75%)
2 characteristics of chromosomal instability pathway to CRC
Sporadic (non familial)
Accumulation of genetic defects
4 characteristics of the microsatellite instability pathway to CRC
Sessile serrated adenomas
Flat, harder to see
Mostly right sided
Often part of genetic syndrome: HNPCC (hereditary non0polyposis colon cancer)
3 non-modifiable risk factors for CRC
Age
Race
Genetics/heredity
4 modifiable risk factors for CRC
Diet
Physical activity
Medications
Associated medical conditions (obesity, diabetes)
2 races more predisposed to CRC
African-American
Ashkenazi Jewish
3 general diet considerations to prevent CRC
Reduce red meat
Increase fruits and vegetables
Increase dietary fibre
3 micronutrients to consider to prevent CRC
Calcium
Vitamin D
Folate (reduce??)
5 reasons to reduce red meat intake
Iron N-nitroso compounds Polycyclic aromatic hydrocarbons Heterocyclic amines Dietary heme
Odd ratio of red meat contributing to CRC
- 1.14 to 1.28
i. e. if you happen to have colon cancer, odds are you ate red meat