Colorectal Carcinoma Flashcards
Define colorectal carcinoma.
Malignant adenocarcinoma of the large bowel
What is the aetiology of colorectal cancer?
Mix of genetic and environmental factors.
Genetic (2-5%): most common family syndromes associated with single gene defects:
- Familial adenomatous polyposis (FAP)
- Lynch syndrome (HNPCC)
Environmental:
- Obesity
- Low dietary fibre intake
- High intake of red and processed meat
What is the epidemiology of colorectal carcinoma?
- 2nd most common cause of cancer-related death and 3rd most common cancer in West
- Average age at diagnosis is 60-65 years
Where are most colorectal carcinomas located?
- 60% = rectum and sigmoid colon
- 15-20% = ascending colon
Remainder in transverse and descending colon
Describe the Dukes’ classification of colorectal carcinoma.
Dukes’ classification for STAGING (spread) and 5 year survival %
A: Limited to the bowel wall - 80-90
B: Through the bowel wall - 60
C: Regional lymph nodes metastasis - 30
D: Distant metastases - <5
What are the symptoms of colorectal carcinoma?
Left-sided
- Change in bowel habit
- Bleeding +/- mucous
- Tenesmus (if rectal mass)
- Change in stool form (small calibre or ribbon-like stools)
Right sided
- Later presentation with symptoms of
- Anaemia
- Weight loss
- Malaise
- +/- Pain
20% of tumours present as emergency with pain and distension caused by large bowel obstruction, haemorrhage and peritonitis as a result of perforation
What are the signs of colorectal adenocarcinoma on examination?
- Anaemia may be the only sign if right-sided
- Abdominal mass
- Low-lying rectal tumours palpable on DRE
- Metastatic disease: hepatomegaly, “shifting dullness” ascites
- Weight loss
- Fistula
When should you do a 2WW referral for suspected colorectal cancer?
- _>_40yrs with unexplained weight loss + abdominal pain, OR
- _>_50yrs with unexplained rectal bleeding, OR
- _>_60yrs with:
- Iron-deficiency anaemia, OR
- Changes in their bowel habit, OR
- Occult blood in their faeces
If younger but presenting with a combination of abdominal pain, change in bowels, weight loss and Fe deficiency.
What investigations would you do for colorectal carcinomas?
Blood
- FBC - ?anaemia
- LFT - normal, often even when liver metastases present
- U&Es - N unless compression of ureters
- Stool - occult or frank blood in stool can be used for screening
Imaging
- CT - may show colonic wall thickening, enlarged lymph nodes, liver metastases, ascites, lung secondaries
- PET scan - focal areas of uptake of 18-fluoro-2-deoxyglucose (FDG) detects malignancy
- Abdominal ultrasound scan - for hepatic metastases
Invasive
- Endoscopy/sigmoidoscopy/colonoscopy +/- biopsy - ulcerating or exophytic mucosal lesion that may narrow the bowel lumen. Or used for polypectomy.
- Barium contrast studies - “apple core” stricture on barium enema
NB: CEA - should only be measured AFTER confirmation of the colorectal cancer; not sensitive or specific enough for screening or diagnosis ; used for monitoring treatment
What is shown?
The photo shows a typical colonic carcinoma stenosing and obstructing the lumen of the colon.
What are these Dukes’ stages?
Dukes’ A - Tumour confined to bowel wall
B - Tumour has invaded beyond bowel wall but there is no lymph node metastasis
C1- Tumour has metastasized to lymph nodes but not to the highest node
C2 - Tumour has metastasized to the highest lymph node
D - Tumour has metastasized to other organs
Dilated transverse colon
NB: lack of small bowel loops on the radiograph – this implies a competent ileocaecal valve, which increases the risk of colonic perforation.
What is this stricture called and what is it characteristic of?
Apple core stricture
Colonic carcinoma
List 3 familial syndromes with colorectal polyps.
- Peutz-Jeghers syndrome
- FAP - Gardner’s, Turcot
- HNPCC
What is the inheritance of FAP?
Autosomal dominant - onset at 25yrs
Mutated APC tumour suppressor gene → minimum 100 polyps
What is the name of the anterior resection procedure for upper rectal cancers?
Hartmann’s
What is the prognosis with colorectal cancers?
