KINESIOL 1Y03 Lecture 27: Pathology of CRC
23 Jun 2018
School
Department
Course
Professor
Pathology of CRC
Up to 20% higher in the W; rising in the E as Western diets are adopted
Increase equalizes in immigrants within a generation
16000 die/year, UK’s second biggest killer
most = >50, mean age 67yo
risk factors: saturated fats, processed/red meat, ghigh MBI, >4units of alcohol per
day, long-standing UC/Crohns, FH
things that lower risk: fruit + veg, folate, selenium, aspirin+ NSAIDs, high calcium
intake
FH: 1/50 chance if no relatives with CRC, 1/17 chance if one first-degree relative, 3
first-degree relatives = 1 in 2 chance, both parents 1/8.5 chance
Genetic factors: HNPCC = 2-3% CRC. FAP = <0.5% CRC, also Turcot’s syndrome,
Peutz-Jeghers, Cowden disease, familial juvenile polyposis
K-ras mutations common test on histopathological sample of resection material
determines chemotherapy regime
Adenomas-carcinoma sequence
= benign polyps with low or high grade dyplasia
residual adenoma seen in 50% in edges of cancer; if not cancer is said to outgrow
the adenoma
adenomas and carcinomas have a similar distribution in the colon
adenomas precede carcinomas by 15 years hence potential for Bowel Cacner
Screening Programme (BCSP)
Polyps can be
1) classic adenomas: either tubular, villous or tubulovillous
- 20% rule determines this: if they are >80% villous, they are villous; if they are <20%
villous they are tubular; if they are >20% villous they are tubulovillous
- can be either sessile (flat) or pedunculated (stalked)
- local invasion is faster with sessile polyps
- pedunculated polyps (larger?) show characteristic histopathological changes with
glands extending into the submucosa due to tortion about the stalk causing
ischaemic changes
2) Hyperplastic (= serrated polyps): rare, can show microsatellite instability mode of
inheritance
3) Early invasive lesion (pT1)
Screening
Nationally administered by Faecal Occult Blood test between 60-75yo
Began in UK 2006
Invited to colonoscopy if blood is present
However only picks up bleeding tumours
2% positive hence go to colonoscopy
can also pick up early pT1 tumours with best survival rates after treatment
however often advanced cancer detected hence need to start screening earlier
hence flexi-sig trial was a recent multicentre randomized controlled trial, currently
piloting at Northwick Park Hospital
trial showed 1 flexi-sig between 55-60 could decrease CRC risk by 38% and mortality
by 43% in those attending; is safe, feasible and more acceptable to patients
Document Summary
Up to 20% higher in the w; rising in the e as western diets are adopted. Most = >50, mean age 67yo risk factors: saturated fats, processed/red meat, ghigh mbi, >4units of alcohol per day, long-standing uc/crohns, fh things that lower risk: fruit + veg, folate, selenium, aspirin+ nsaids, high calcium intake. Fh: 1/50 chance if no relatives with crc, 1/17 chance if one first-degree relative, 3 first-degree relatives = 1 in 2 chance, both parents 1/8. 5 chance. K-ras mutations common test on histopathological sample of resection material determines chemotherapy regime. Polyps can be: classic adenomas: either tubular, villous or tubulovillous. 20% rule determines this: if they are >80% villous, they are villous; if they are <20% villous they are tubular; if they are >20% villous they are tubulovillous. Can be either sessile (flat) or pedunculated (stalked) Local invasion is faster with sessile polyps. Nationally administered by faecal occult blood test between 60-75yo.
