L13 Colonic Cancer Flashcards
At what age does the risk of colon cancer begin?
40-45 (Risk Doubles w/ each succeeding decade)
Percent of the Population at risk of colon cancer?
Contribution of genetics/Environment to risk?
5%
20% genetic, 80% environmental (lifestyle, diet => influences microbiome)
Risk factors of Colon Cancer?
- Processed meat (WHO group 1 carcinogen)
- Red meat (group 2A –probable)
- Cigarettes
- Alcohol
- High BMI
*Sulfur-Metabolizing Microbiome
Protective factors for colon cancer?
*Healthy diet
*Physical activity
*Medication: HRT, NSAIDs
GOAL=Diverse microbiome with short-chain fatty acid-producing anaerobes & fiber-fermenting bacteria
Clinical Presentation of Colorectal Cancer?
- Change of bowel habit
- Mucus or blood PR
- Anemia (Iron deficiency)
- Pain if an obstruction
Investigations for Colorectal Cancer?
Physical Rectal Exam
Fecal Occult Blood (FIT Positive 50% adenoma, 50% Carcinoma)
Endoscopy (Screening Programs)
Biopsy
CT Collagraphy
5 year survival of Various stages of Colorectal Cancer?
_________________________________:
Left-Sided, Benign Neoplastic Polyps of the Rectosigmoid
Two Types (based on cytoplasmic Differentiation):
________________________
________________________
Usually _________ diameter.
Usually affects ________________
Hyperplastic Polyp:
Left-Sided, Benign Neoplastic Polyps of the Rectosigmoid
Two Types (based on cytoplasmic Differentiation):
Micro-vesicular (most common)
Goblet cell rich
Usually < 5mm in diameter.
Usually middle to old age ( mean 62 years)
__________________________
Right-sided Benign Lesion of the colon responsible for ______of CRCs
Risk of developing ____________________________ within the polyp.
→ should be removed where possible.
Usually _______________ in diamter
Associated with ________________________________
*Sessile Serrated Lesion (SSL): *
Right-sided Benign Lesion of the colon responsible for 30% of CRCs
Risk of developing high grade dysplasia and carcinoma within the polyp.
→ should be removed where possible.
Usually *large (typically > 10mm) *
SSLs associated with synchronous advanced colorectal neoplasia
Sessile Serrated Lesion (SSL) with _________ carry an increased & accelerated risk of progression
Sessile Serrated Lesion (SSL) with dysplasia carry an increased & accelerated risk of progression
Evidence fot Adenoma-Carcinoma Sequence?
Risk of development of Malignanacy in Adenomas?
- Size > 1cm (large size is the most important risk factor)
- Multiple adenomas
- High-grade dysplasia
- Prominent villous component
Most common type of colorectal cancer and its location?
Adenocarcinoma (98%)
Rectosigmoid most common location
Colon Cancer with 1 metastatic lesion, can be resected, survival rate high
Oligometastatic
Risks/Manifestations of Cancer in Ulcerative Colitis
<1% of all Colon Cancer
Risks
a) > 8-10yrs
b) pan-colitis
Flat pre-malignant dysplasia
May be multifocal
Aggressive
Advanced stage at diagnosis
Examples of Colorectal Cancer Syndromes and their inheritance?
Inheritance/Pathogenesis of Lynch Syndrome?
Autosomal Dominant Inheritance
Usually inherited, can be new mutation
Most common form of familial Colorectal Cancer (3% CRC)
Caused by mutation in mismatch repair gene (MMR) leading to microsatellite instability
Most common form of familial Colorectal Cancer?
Lynch Syndrome - 3% CRC
Inheritance/Pathogenesis/Epidemiology/Manifestations of Lynch Syndrome?
Familial Adenomatous Polyposis:
Autosomal Dominant Inheritance
Loss of APC Gene!!- APC targets Beta-catenin for degradation (Wnt pathway)
=> Colorectal adenocarcinomas < 40 years old
> 100 polyps predominantly in the large intestine (typically 1000s of polyps!!)
Extra-intestinal manifestations
Duodenal carcinoma desmoid tumour (fibromatosis) commonest cause of death
Commonest cause of death for Pts. with Familial Adenomatous Polyposis?
Duodenal carcinoma desmoid tumour (fibromatosis)
Inheritance/ Epidemiology/Manifestations of MYH-Associated Polyposis
Autosomal recessive inheritance
Mean age of cancer diagnosis = 50 years old
Penetrance near 100%.
Clinically similar to attenuated FAP (30% of NON-APC Familial Adenomatous Polyposis)
Inheritance/Epidemiology/Manifestations of Serrated Polyposis?
Unknown Genetics
Develop multiple serrated polyps:
20 serrated polyps (Hyperplastic or SSLs) of any size distributed throughout the colon
Up to 50% may develop colorectal cancer
