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Colorectal cancer:

Dr. Mohamed Shekhani

2012

Contents

CRC clinical presentations2

Familial CRC4

Sporadic CRC33

CRC location distribution.31

Contents

CRC Precursors2

CRC screening4

Hereditary CRC syndromes33

CRC Epidemiology31

CRC: Epidemiology/risk factors

Sporadic average riskMost 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

CRC

Epidemiology

Hereditary CRC

syndromes:Higher than average

CRC risk &include:

FAP

AFAP

HNPCC

IBD

Familial CRC.

Stratification of Colorectal Cancer Risk

Most

minority

Text

Average risk-ve family

history

LTR 5-6%>50 years.

High risk

•FAP 100%•HNPCC 10%•IBD 10-20%

•Familial FDR 10%Occur earlier <50

years.

CRC Risk

ALL

Risk/protective factors for CRC

CRC

Risk factors

Hereditary CRC

IBD

WESTERN

No family H/O CRC

Asia/Africa

High veg;fruits/

calcium/folate

protective factors

Physical inactivity

High red meat,

sucrose,fat

Low calcium/folate.

Obesity,smoking,

Alcohol,

cholecystectomy

Physical activity

Adenoma-carcinoma sequence develop over

10 years: rationale for screening

CRC: Adenoma-carcinoma sequence

Rationale for screening by colonoscopy

CRC

LAP with dysplasia

Large adenomatous polyps

Small adenomatous polyps

Normal

Screening for early detection

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.

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

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

Hereditary CRC Syndromes: AFAP

Mutations at the terminal end of

the APC gene

20 or more adenoma

SAME RISK OF CRC.

AFAP

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

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

Hereditary CRC Syndromes: others

Familial juvenile polyposis

the Peutz-Jeghers syndrome

(hamartomatous polyps)

Both at increased risk for developing CRC.

others

IBD CRC risk

Duration > 8 years of active colitis

Early age of onset

Extent

Presence of PSC.

IBD CRC Risk

Algorithm for screening for CRC

Management

Surgery is the only hope for cure.

Carcinomas within 2 cm of the anal verge may require abdomin-

operineal 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.

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2012