Colorectal cancer

Question 1

What is colorectal cancer?

Answer 1

Cancer of the colon and rectum.
3rd most common malignancy.
Usually adenocarcinoma on histology.

Question 2

What are the signs and symptoms of colorectal cancer?

Answer 2

Abdominal pain
Unintentional weight loss
Altered bowel habit
Faecal occult blood
Anaemia
Fatigue

Question 3

What are the causes of colorectal cancer?

Answer 3

Multifactorial and often unknown.

There are risk factors that may predispose.

Question 4

What investigations are performed to confirm colorectal cancer?

Answer 4

Bowel cancer screening programme: faecal occult blood test in men and women aged 60-69 years.
Bloods: FBC for iron deficiency anaemia and carcinoembryonic antigen (CEA) tumour marker.
Endoscopy: colonoscopy/sigmoidoscopy.
Imaging: double contrast barium enema study ‘apple core’ sign; virtual colonoscopy.

Question 5

What is the treatment of colorectal cancer?

Answer 5

Depends on the extent of disease. Assessed using Duke’s staging system or TNM system.
Conservative: patient education and referral to Macmillan nurses.
Medical: chemotherapy (oxaliplatin, folinic acid and 5-flurouracil is the most common regime); radiotherapy may also be used.
Surgery: surgical resection is usually treatment of choice.

Question 6

What is the complication of colorectal cancer?

Answer 6

Obstruction and metastasis.

Question 7

What are the risk factors for colorectal cancer?

Answer 7

Smoking.
Increased age.
Family history.
IBD.
Streptococcus bovis bacteraemia.
Congenital polyposis syndromes: juvenile polyposis syndrome (autosomal dominant but may occur spontaneously, not malignant); Peutz-Jegher’s syndrome (autosomal dominant, increased risk of CRC, melanosis is present on oral mucosa).
Genetic predisposition: familial adenomatous polyposis (FAP; autosomal dominant, mutation of APC gene on chromosome 5, 100% lead to CRC); hereditary nonpolyposis colorectal cancer (HNPCC; autosomal dominant, mutation of DNA mismatch repair gene).

Question 8

Explain the Duke’s staging system.

Answer 8

Stage A: confined to muscularis mucosa, 90% 5 year survival.
Stage B: extends through muscularis mucosa, 65% 5 year survival.
Stage C: lymph node involvement, 30% 5 year survival.
Stage D: distant metastases, <10% 5 year survival.

Question 9

Explain the TNM system.

Answer 9

T: carcinoma in situ
T1: submucosa invaded
T2: muscularis mucosa invaded
T3: tumour has invaded subserosa but other organs have not been penetrated
T4: adjacent organs invaded

N1: metastatic spread to 1-3 regional lymph nodes
N2: metastatic spread to >4 regional lymph nodes

M0: no distant metastases present
M1: distant metastases present