Colorectal cancer Flashcards
(12 cards)
What is the global rank of CRC incidence, and what dietary factors increase risk?
4th most common cancer. Risk ↑ with low fiber, high red meat, refined carbs, and fat
What is the significance of iron deficiency anemia in an older adult?
GI cancer (e.g., CRC) until proven otherwise, especially in men/postmenopausal women
Compare the genetic basis of FAP vs. Lynch syndrome
FAP: APC mutation → 100s of adenomas by age 25.
Lynch: MSH2/MLH1 mutation → microsatellite instability (no polyps)
What is the screening protocol for Lynch syndrome carriers?
Regular endoscopy from young adulthood (due to high CRC risk)
What is the most common precursor lesion for CRC?
Adenoma (villous/tubular) → adenocarcinoma
How does 5-year survival vary by stage?
Stage 1: 90%, Stage 2: 80%, Stage 3: 70%, Stage 4: 10%
What is the UK’s CRC screening method and age range?
Faecal Immunochemical Test (FIT) every 2 years for ages 60-74 (expanding to 50+)
How do right-sided vs. left-sided CRC typically present?
Right: Iron deficiency anemia, occult bleeding.
Left: Change in bowel habit, rectal bleeding (often misdiagnosed as hemorrhoids)
What is the curative treatment for Stage 1-3 CRC?
Surgery (tumor + lymph node resection) ± adjuvant chemo (CapeOx for Stage 3).
How does metastatic CRC treatment differ for MSI vs. non-MSI tumors?
Non-MSI (95%): FOLFOX/FOLFIRI ± EGFR inhibitors (if RAS/RAF wild-type).
MSI (5%): PD-1 inhibitors (40% cure due to high neoantigen load).
MSI-H and MSS biomarkers indicate the stability of the DNA in a tumor. Colorectal cancer tumors are often referred to as having an “MSI status,” meaning they are described as either MSI (microsatellite instable) or MSS (microsatellite stable)
Why do BRAF inhibitors fail in CRC, and how is this overcome?
Feedback loop activates EGFR → combo with EGFR inhibitors (e.g., cetuximab) blocks resistance
What symptom in a young adult should prompt CRC evaluation?
Persistent rectal bleeding/bowel changes (often misattributed to hemorrhoids/IBS)
