Colorectal carcinoma

Question 1

Define colorectal carcinoma and its epidemiology

Answer 1

Colorectal carcinoma is a malignant adenocarcinoma of the large bowel.

Epidemiology: 2nd most common cancer death in west. 20,000 deaths/ yr in UK. Avg age 60-65 yrs

Question 2

What is the aetiology of colorectal carcinoma?

Answer 2

• Environmental and genetic factors.
• Thought to occur in a sequence of epithelial dysplasia —–>adenoma—–> carcinoma. This sequence involves an accumulation of genetic changes oncogenes (e.g. APC, K-ras) and tumour suppressor genes (e.g. p53, DCC).
• 60% occur in sigmoid colon
• 15-20% in ascending colon
• Rest in transverse and descending.
• Some inherited conditions associated with high rates of colorectal cancer. As well as chronic bowel inflammation

Question 3

Describe the history/presenting symptoms of colorectal carcinoma

Answer 3

Symptoms dependant on location of tumour.
- Left sided colon and rectum: Bowel habit change, rectal bleeding/ blood mucus in stool. Rectal masses may present as tenesmus (sensation of incomplete emptying)

• Right sided colon: Later presentation, with symptoms of anaemia, weight loss and non-specific malaise, rarely lower abdominal pain.

Up to 20% of tumours present as an emergency with pain and distention caused by large bowel obstruction, hemorrhage or peritonitis as a result of perforation.

Question 4

What are the signs of colorectal carcinoma upon physical examination?

Answer 4

• Anaemia may be the only sign, esp in right sided lesions.
• Abdominal mass
• Low lying-rectal tumours may be palpable in rectal examination.

If metastatic: Hepatomegaly, ‘shifting dullness’ of ascites.

Question 5

What investigations are used to identify colorectal carcinoma?

Answer 5

• Blood: FBC (for anaemia), LFT, tumour markers (for treatment response/ disease recurrence)
• Stool: Occult or frank blood in stool (can be used as a screening test)
• Endoscopy: Sigmoidoscopy, colonoscopy. For visualization and biopsy. Polypectomy can be performed if isolated small carcinoma in situ.
• Barium contrast: studies: ‘Apple core’ stricture on barium enema.
• Abdominal ultrasound scan: Hepatic metastases detection.

CXR, CT or MRI, endorectal ultrasound may also be used

Question 6

How is colorectal carcinoma surgically managed?*

Answer 6

It is the only curative treatment. Operation depends on circumstance:

• Right Hemicolectomy- Caecum, ascending and proximal transverse colon
• Left Hemicolectomy- Distal transverse and descending colon.
• Sigmoid colectomy- sigmoid colon
• Anterior resection- high rectum
• Abdo-perennial resection with end colostomy formation- low rectum

Question 7

What are the complications of colorectal carcinoma?*

Answer 7

Bowel obstruction or perforation, fistula formation. Recurrence. Metastatic disease.

Question 8

Summarise the prognosis for patients with colorectal carcinoma*

Answer 8

Prognosis varies depending on Dukes’ staging:

A- Confined to bowel wall (80-90% 5 year survival)
B- Breached serosa, -ve lymph nodes (60% 5 year survival)
C- Breached serosa, +ve lymph nodes (30% 5 year survival)
D- Distant Metastases (<5% 5 year survival)

Question 9

What are the other ways of managing colorectal carcinoma?*

Answer 9

• Emergency- Hartmann’s procedure (proximal colostomy, resection of tumour and oversaw of distal lump). Survival in rectal tumours is improved if surrounding fascia removed.
• Radiotherapy- May be given as a Add to neoadjuvent to decrease tumour prior to resection or to prevent recurrence.
• Chemotherapy- Used as adjuvant therapy in Dukes’ C (sometimes B)