CRC

1. LOGO
Colorectal cancer:
Dr. Mohamed Shekhani
2012

2. Contents
3
1
CRC location distribution.
2
CRC clinical presentations
3
Sporadic CRC
4
Familial CRC

3. Contents
3
1
CRC Epidemiology
2
CRC Precursors
3
Hereditary CRC syndromes
4
CRC screening

7. CRC: Epidemiology/risk factors
CRC
Epidemiology
Sporadic average risk
Most common GIT cancer
3rd most common cancer
2nd most common cancer
death
2% die from this cancer.
Men>women
Blacks>white
Increase sharply after 50
Hereditary CRC
syndromes:
Higher than average
CRC risk &include:
FAP
AFAP
HNPCC
IBD
Familial CRC.

9. Stratification of Colorectal Cancer Risk
CRC Risk
High risk
Average risk
-ve family
history
Most
LTR 5-6%
>50 years.
FAP 100%
•HNPCC 10%
•IBD 10-20%
•Familial FDR 10%
Occur earlier <50
years.
•
minority
Text
ALL

10. Risk/protective factors for CRC
protective factors
Risk factors
Hereditary CRC
IBD
WESTERN
No family H/O CRC
CRC
Asia/Africa
High veg;fruits/
calcium/folate
Physical inactivity
High red meat,
sucrose,fat
Low calcium/folate.
Obesity,smoking,
Alcohol,
cholecystectomy
Physical activity

11. Adenoma-carcinoma sequence develop over
10 years: rationale for screening

12. CRC: Adenoma-carcinoma sequence

13. Rationale for screening by colonoscopy
CRC
LAP with dysplasia
Screening for
early detection
Large adenomatous polyps
Small adenomatous polyps
Normal
30-50% of adults develop adenomatous polyps during their lifetime, but only 1 / 20
will progress to cancer.
15-25% >50 ys have adenomatous polyps, males>females.

14. Hereditary CRC Syndromes: FAP
Mutation in APC genes
100% will develop 100s of
adenomatous colonic polyps & cancer
By 40 years age.
GIT Extra colonic tumors:
2nd most common after colonic;
adenoma/adenocan of ampulla of vater,
Fundal gland polyps.
FAP

15. Hereditary CRC Syndromes: FAP
Need screening colonoscopy earlier than
The usual age of 50 years
Extra GIT Features:
Bone/soft tissue tumors
Retinal pigment epith hypertrophy
Treatment:
Total colectomy with ileostomy to
prevent cancer.
FAP

16. Hereditary CRC Syndromes: AFAP
Mutations at the terminal end of
the APC gene
20 or more adenoma
SAME RISK OF CRC.
AFAP

17. Hereditary CRC Syndromes: HNPCC
Mutations at DNA MMR gene
Polyps larger
more in proximal colon
Progress more rapidly to CRC.
8O% develop cancer >50
Vs 5% > 50 in average risk persons.
Extra-colonic tumors:FRS,Kid,pancbil,SI
HNPCC

18. Hereditary CRC Syndromes: familial
Do not meet criteria for FAP or HNPCC
1ST degree or 2nd degree relative with
CRC before or after 50
Risk increase with increasing numbers of
Affected relatives.
Familal CRC

19. Hereditary CRC Syndromes: others
Familial juvenile polyposis
the Peutz-Jeghers syndrome
(hamartomatous polyps)
Both at increased risk for developing CRC.
others

20. IBD CRC risk
Duration > 8 years of active colitis
Early age of onset
Extent
Presence of PSC.
IBD CRC Risk

21. Algorithm for screening for CRC

23. Management
 Surgery is the only hope for cure.
 Carcinomas within 2 cm of the anal verge may require abdominoperineal resection & colostomy.
 Postoperative colonoscopy after 6–12 months &periodically
thereafter for local recurrence or new ‘metachronous’ lesions,
occuring in 6% of cases.
 Adjuvant radio-chemotherapy for rectal cancer.
 Paliative chemo-radiotherapy or stenting for inoperable cases.

24. LOGO
2012