6.11 - Gastrointestinal cancers Flashcards
What is a cancer?
A disease caused by uncontrolled division of abnormal cells in a part of the body
What is a primary cancer?
Arising directly from the cells in an organ
What is a secondary cancer/metastasis?
Spread from another organ, directly or by other means (blood or lymph)
What are GI tract squamous cell (epithelial) cancers called?
Squamous cell carcinoma (SCC)
What are GI tract glandular epithelium cell (epithelial) cancers called?
Adenocarcinoma
What are GI tract enteroendocrine cell (neuroendocrine) cancers called?
Neuroendocrine tumours (NETs)
What are GI tract interstitial cells of Cajal (neuroendocrine) cancers called?
Gastrointestinal stromal tumours (GISTs)
What are GI tract smooth muscle cell (connective tissue) cancers called?
Leiomyoma / leiomyosarcoma
What are GI tract adipose tissue cell (connective tissue) cancers called?
Liposarcoma
Where can GI neuroendocrine tumours occur?
Throughout the whole GI tract
How common is colorectal cancer?
- most common GI cancer in Western societies
- third most common cancer death in men and women
What is the lifetime risk of colorectal cancer in men and women?
- 1 in 10 for men
- 1 in 14 for women
Which age group does colorectal cancer affect the most?
Generally affects patients >50 years (>90% of cases)
What are the three forms of colorectal cancer?
- sporadic
- familial
- hereditary syndrome
What are the criteria for sporadic colorectal cancer? (3)
- absence of family history
- older population
- isolated lesion
What are the criteria for familial colorectal cancer? (2)
- family history
- higher risk if index case is young (<50 years) and the relative is close (1st degree)
What are the criteria for hereditary colorectal cancer? (3 + examples)
- family history
- younger age of onset
- specific gene defects
- e.g. familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome)
What is the histopathology (type of cancer) for all three types of colorectal cancer?
Adenocarcinoma
Describe the progression of colorectal cancer.
Normal epithelium –> (APC mutation) –> hyperproliferative epithelium, aberrant cryptic foci, polyp (COX-2 overexpression) –> small adenoma –> (K-ras mutation) –> large adenoma –> (p53 mutation) –> (loss of 18q) –> colon carcinoma
What do we do for people with a polyp / 50+ years old (colorectal cancer)?
- routine colonoscopies to screen for new polyp development
- straightforward to endoscopically remove polyps before they become colorectal cancer - prophylactic endoscopic polyp/adenoma resections
- this is because over years a small polyp can become a large cancer
What does aspirin/NSAIDs do in colorectal cancer development?
Protects against the development of colorectal cancer
What are the risk factors for developing colorectal cancer?
- past history
- colorectal cancer
- adenoma, ulcerative colitis, radiotherapy
- family history
- 1st degree relative <55 years
- relatives with identified genetic predisposition (e.g. FAP, HNPCC, Peutz-Jegher’s syndrome)
- diet/environmental
- carcinogenic foods?
- smoking
- obesity
- socioeconomic status
What are the locations that colorectal cancers are found in?
- 2/3 in descending colon (left colon) and rectum
- 1/3 in sigmoid colon and rectum (i.e. within reach of flexible sigmoidoscopy)
How do caecal and right-sided colorectal cancer patients present?
- iron deficiency anaemia (most common)
- change of bowel habits (diarrhoea)
- distal ileum obstruction (late)
- palpable mass (late)
How do left-sided and sigmoid carcinoma colorectal cancer patients present?
- PR (rectal) bleeding (fresh red blood), mucus
- thin stool (pencil-type stools = late)
How do rectal carcinoma colorectal cancer patients present?
- PR (rectal) bleeding, mucus
- tenesmus - the feeling of needing to open bowels but nothing comes out when you try
- anal, perianal, sacral pain (late)
What kind of sign of colorectal cancer is bowel obstruction?
Late sign
What are some signs of local invasion (late) of colorectal cancer? (2)
- bladder symptoms
- female genital tract symptoms
Where can colorectal cancer metastasise to (late sign) and how can these present? (5)
- liver (hepatic pain, jaundice, hepatomegaly)
- lung (cough, monophonic wheeze)
- bone (bone pain)
- regional lymph nodes (e.g. inguinal)
- peritoneum (Sister Marie Joseph nodule is metastasis in umbilicus)
What are some signs of primary colorectal cancer? (4)
- abdominal mass
- digital rectal examination (DRE): most <12cm from dentate line and reached by examining finger
- rigid sigmoidoscopy (bedside/outpatient test)
- abdominal tenderness and distension - large bowel obstruction
What are the signs of metastasis and complications of colorectal cancer? (3)
- hepatomegaly (liver)
- monophonic wheeze (lung)
- bone pain (bones)
What investigations can we do for colorectal cancer? (6)
- faecal occult blood
- blood tests
- colonoscopy
- CT colonoscopy/colonography
- MRI pelvis
- CT chest/abdo/pelvis
What two types of faecal occult blood tests for colorectal cancer are there?
- Guaiac test (Hemoccult) - based on pseudoperoxidase activity of haematin
- 40-80% sensitivity and 98% specificity
- dietary restrictions - avoid red meat, melons, horseradish, vitamin C and NSAIDs for 3 days before test
- FIT (faecal immunochemical test) - detects minute amounts of blood in faeces (faecal occult blood)
What two types of blood tests are there for colorectal cancer?
- FBC - anaemia, haematinics (low ferritin)
- tumour markers - CEA (carcinoembryonic antigen) which is useful for monitoring evidence of recurrence but NOT as a diagnostic tool
What does colonoscopy do for colorectal cancer?
- can visualise lesions <5mm
- small polyps can be removed = reduced cancer incidence
- pedunculated polyp (with stalk) –> wire around it + heat to cut and close wound to prevent bleeding
- usually performed under sedation
How does CT colonoscopy/colonography compare with normal colonoscopy (colorectal cancer)?
- can visualise lesions >5mm (not under)
- no need for sedation
- less invasive, better tolerated
- if lesions identified then patient needs colonoscopy for diagnosis
When do we do MRI pelvis for (colo)rectal cancer?
- if you have a tumour you think is relatively advanced
- look at: depth of invasion, mesorectal lymph node involvement - to see whether we can do R0 resection (take all cancer out with good margin)
- no bowel prep or sedation required
- help choose between preoperative chemotherapy (to reduce tumour size) or straight to surgery
- is the CRM (circumferential resection margin - prognostic predictor) threatened?
Why is CT chest/abdo/pelvis done for colorectal cancer?
Staging prior to treatment to exclude liver or lung metastases
What is the primary management for colorectal cancer?
Surgery
What can you do to give yourself time to plan colorectal cancer surgrey?
Put in a stent, or use radiotherapy / chemotherapy
What do you do with a right and transverse colon obstructing carcinoma?
- resection and primary anastomosis - resect and join up straight away with primary anastomosis as blood supply is good so will not leak
- usually do not obstruct as more leeway for carcinoma to expand
Right / extended right hemicolectomy
Why do you have to be more careful with a left colon obstruction?
Blood supply to left colon is not as good as to right colon
What can you do with a left colon obstructing carcinoma? (3)
- Hartmann’s procedure
- proximal end colostomy (LIF) - remove tumour, instead of joining proximal bowel and rectum, bring proximal bowel up to skin and do a colostomy (staple distal end)
- reversal in 6 months if patient is okay
- primary anastomosis (join up proximal bowel and rectum) but not safest:
- intraoperative bowel lavage with primary anastomosis but 10% chance of leak due to poor blood supply
- defunctioning ileostomy
- palliative stent
What is the difference between a stoma on the left or right side of a patient?
- left side = colostomy (large bowel)
- right side = ileostomy (small bowel)
What are the most important right-sided colonic arteries? (3)
- ileocolic
- right colic
- middle colic
What are the most important left-sided colonic arteries? (2)
- left colic
- when we get to the pelvis, sigmoid arteries are important
What is resection of the bowel dependent on?
Blood supply to that region
What is a right hemicolectomy?
Remove right colon, then anastomose terminal ileum to transverse colon
What is an extended right hemicolectomy?
- take around 2/3 of large bowel out - right colon and part of transverse
- then do ileocolic anastomosis (ileum to remaining colon)
What is a left hemicolectomy?
Resect left colon then anastomose remaining colon parts
Why is a rectal cancer resection difficult and what can we do?
- blood supply around rectum/anus is poor
- we can do the resection and join up the other parts (e.g. colon to anus), and then do an ileostomy (bring up loop of small bowel to skin to divert faeces going through delicate anastomosis)
What are some different types of liver cancer? (3 + 1)
- primary liver cancer - hepatocellular carcinoma (HCC)
- gallbladder cancer (GB CA)
- cholangiocarcinoma (ChCA)
- (colorectal cancer CRC can also affect the liver)