Colorectal Cancer and Screening

Question 1

What are the risk factors of colorectal cancer?

Answer 1

Sporadic (85%)
Familial (10%)
Inheritable conditions: HNPCC (5%), FAP (<1%), other CRC syndromes
IBD (1%)

Question 2

What are the risk factors for sporadic cases of colorectal cancer?

Answer 2

Age
Male
Previous adenoma/CRC
Environtment (diet, obesity, lack of exercise, smoking, diabetes mellitus)

Question 3

What are colorectal polyps?

Answer 3

Protuberant growths
Variety of histological types
Epithelial or mesenchymal
Benign or malignant

Question 4

What are adenomas?

Answer 4

Benign, pre-malignant growths from epithelial origin

Question 5

What are the 2 main histological types of adenomas?

Answer 5

Tubular (75%)
Villous (10%)
(indeterminate tubulovillous also - 15%)

Question 6

What is the presentation of colorectal cancer?

Answer 6

Rectal bleeding - mixed w/ stool
Altered bowel opening to loose stools
Iron deficiency anaemia (men of any age and non-menstruating women)
Palpable rectal or r. lower abdominal mass
Acute colonic obstruction
Systemic symptoms: weight loss, anorexia

Question 7

What are the investigations for colorectal cancer?

Answer 7

Colonoscopy - allows biopsy
Radiological imaging (ba enema, CT colonography, CT abdo/pelvis)

Both require bowel prep

Question 8

What investigations are used for staging in colorectal cancer?

Answer 8

CT scan chest/abdo/pelvis
MRI for rectal tumours
PET scan/rectal endoscopic USS

Question 9

What is the treatment for colorectal cancer?

Answer 9

Surgery (~80%) - depends on site, size, stage - stoma formation (may or may not be permanent)
Chemotherapy after surgery
Radiotherapy - rectal cancer only - before surgery to control primary tumour

Question 10

What are the palliative care options for colorectal cancer?

Answer 10

Chemotherapy

Colonic stenting to prevent obstruction

Question 11

What are the modalities used in screening?

Answer 11

Faecal occult blood test (FOBT)
Faecal immunochemical test (FIT)
Flexible sigmoidoscopy
Colonscopy
CT colography

Question 12

What is the scottish bowel screening programme?

Answer 12

Ages 50–74
FOBT every 2 years
If FOBT +ve = colonscopy

Question 13

What are the high risk groups of colorectal cancer?

Answer 13

Heritable conditions - FAP, HNPCC
IBD
Familial risk
Previous adenomas/colorectal cancer

Question 14

What is FAP?

Answer 14

Multiple adenomas throughout colon
50% by 15 years old, 95% by 35
Mutation of the APC gene on chromosome 5
High risk of malignant change

Question 15

What is the screening procedures for FAP?

Answer 15

Annual colonoscopy from age 10-12

Prophylactic proctocolectomy from age 16-25

Question 16

What are the extracolonic manifestations of FAP?

Answer 16

Benign gastric fundic cystic hyperplastic
Duodenal adenoma (90%) with periampullary cancer ~5%

Question 17

What is HNPCC?

Answer 17

Mutation in DNA mismatch repair genes

Question 18

How is HNPCC associated with cancer?

Answer 18

Early onset colorectal cancer right sided

Associated with other cancers: endometrial, genitourinary, stomach, pancreas