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Flashcards in Colon Deck (29)
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What are risk factors for colorectal cancer?

Age (70% of patients with CRC are over 65y)
Physical inactivity
High red meat consumption
Heavy alcohol intake
Family history and inherited syndromes


Clinical presentation of CRC?

Change in bowel habit, abdo pain, weight loss, anaemia iron deficiency, PR bleeding


What are options for screening for CRC?

Flexible sigmoidoscopy
CT colongraphy
Faecal occult blood (shown to reduce CRC mortality by 32%)


When to screen average population?

Start at age 50y
Continue until life expectancy


When to screen for CRC in IBD?

if crohns colitis or ulcerative colitis - start colonscopic screening after 8 years of disease, then annually


When to screen in patients with family history?

If family history of CRC


When to screen Lynch syndrome?

Colonscopy every 1-2 years starting at age 20-25, or 5y before youngest case in family


When to screen FAP?

Sigmoidoscopy every 2 years starting age 12-14, once adenomas detected then annual colonoscopy until colectomy


How to diagnose CRC?

Colonoscopy - biopsy, removal of polyps
LFTs, CT abdo/pelvis, CXR


What is value of CEA test?

Low diagnostic ability (sensitivity 46%, specificity 89%)
Prognostic value - if CEA >5 pre op = worse prognosis
Useful monitoring test post operatively


What is the staging of CRC?

Need adequate sampling of at least 12 nodes
Stage 1: confined to muscularis
Stage 2: invasion through muscularis into pericolorectal tissues
Stage 3: spread to lymph nodes
Stage 4: distant metastases


What are high risk features of Stage 2 CRC?

Presentation with perforation or obstruction
Inadequate lymph node sampling (


What is the management strategy for Stage 1-2 CRC?

Wide surgical resection
No role for adjuvant chemotherapy

* if high risk stage 2 - can consider adjuvant chemotherapy


What is the management strategy for Stage 3 CRC?

Wide surgical resection
Standard of care is adjuvant doublet chemotherapy with oxaliplatin and 5-FU derivative (capecitabine or 5-FU)


How is advanced CRC stratified?

Resectable disease - resect with perioperative or post operative chemotherapy
Potentially resectable disease - neoadjuvant chemotherapy to down stage disease in attempt to become resectable
Unresectable disease - palliative chemotherapy


What are the options for unresectable advanced CRC?

Backbone of treatment is 5-FU chemotherapy
Cycle combinations of 5-FU, oxaliplatin and irinotecan
Targeted therapies (bevacizumab and cetuximab) improve OS in first line


When can cetuximab be used?

Only proven in KRAS wildtype (no RAS mutation)
Only in advanced disease


What is recommended follow up after adjuvant treatment?

Colonosopy in first years, then every 3-5 years
History, physical examination and CEA monitoring everyr 3-6 months for 3 years, then every 6-12 months for next 2 years
CT CAP every 6-12 months for 3 years in high risk pt


What is mutation in Lynch syndrome?

Mutations in mismatch repair genes (MMR)
Most common is MLH1 or MSH2 (account for 80%)
Also MSH6, PMS2
Mutations result in tumour DNA microsatellite instability


What are patients with Lynch syndrome at risk of?

Colorectal cancer (30-70%)
Endometrial ca (30-60%))
Urinary tract ca
Small intestine ca
Ovary ca
Gastric ca
Pancreatic ca
Biliary tree ca
Skin ca
Brain ca


What are Bethesda guidelines?

When to test patient with CRC for MSI (Lynch syndrome)
- age


What is FAP, what are the manifestations and mutations involved?

Familial adenomatous polyposis
Autosomal dominance inheritance
APC mutations - correlate with number of polyps
Presence of multiple polyps in colon and rectum
Extraintestinal manifestations: gastric and duodenal polyps, desmoid tumours, thyroid and brain cancer, supernumerary teeth


What are the two types of FAP?

Classical - more thatn 100 polyps, complete penetrance, will develop CRC by 40-50y
Attenuated - fewer polyps, later onset of disease, incomplete penetrance, develop CRC at 50-60y


What is most important aspect of management of rectal cancer?

Excision of mesorectum (technically difficult)
Requires staging with MRI to adequately asses tumour penetration
If full thickness -- standard of care is pre-operative chemoradiation with 5-FU, followed by surgery, followed by adjuvant chemotherapy


What is the main association and risk factors for anal cancer?

Associated with Human Papilloma Virus (HPV) in 80-85%)
Increased risk in HIV positive, MSM, immunosuppresion


What is treatment strategy for anal cancer?

Tends to relapse loco-regionally
First line treatment is radical chemoradiation with Mitomycin/5-FU and external beam radiation
If relapse - proceed to salvage surgery


What is MSI and how does it occur?

Microsatellite instability
Occurs when abnormalities of the mismatch repair proteins mean that they are unable to correct errors occurring during DNA replication
This causes repeated sequences of DNA (called micro satellites)

Presence of MSI indicates that there is an abnormality of MMR (mismatch repair)


What are the types of mutations causing MSI?

Sporadic - caused by hyper methylation of MLH 1 gene promotor
Germline - mutations of MLH1 or MSH2 (80%), MSH6 or PMS2 (20%)


What are the clinical features of MSI- H colorectal cancer?

Proximal tumours
Poorly differentiated
Often mucinous or signet ring
Less likely to metastasize
Younger patients
Better prognosis than micro satellite stable CRC
Often chemo resistant
Respond better to surgery alone (esp stage 2)