GI CANCERS Flashcards
Define cancer
A disease caused by uncontrolled division of abnormal cells in any part of the body
Difference between primary cancer and secondary cancer (metastasis)
Primary cancers arise directly from the cells of an organ
Secondary cancers spread to an organ, either directly or by other means (blood, lymph)
Name the types of cancers based on cell type, giving GI examples for each
What age group is most commonly affected by colorectal cancer?
> 50 years (more than 90% of cases)
What is lifetime risk of colorectal cancer in men and women?
How common is it?
- 1 in 10 for men
- 1 in 14 for women
- Most common GI cancer in the West
- 3rd most common cancer death
What are the three forms of colorectal cancer?
Sporadic- Absence of family history, older population, isolated lesion
Familial- Family history, higher risk if index case is young (<50years) and the relative is close (1st degree)
Hereditary-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 colorectal cancer?
Adenocarcinoma
Describe the progression of colorectal cancer
b) What does this mean for people who have 1 polyp?
c) What does aspirin do?
b)- They get repeat colonoscopies to check for new polyps developing
- It’s straightforward to endoscopically take polyps away before they become cancer- prophylactic endoscopic polyp/adenoma resections
c)Protects against the development of this pathway below
What are the 3 types of risk factors for colorectal cancer
Past medical history
-Colorectal cancer
-Adenoma (polyps), ulcerative colitis, radiotherapy treated patients
Family history
- 1st degree relative <55 years
- Relatives with identified genetic predisposition e.g.
- FAP
- HNPCC
- Peutz-Jegher’s syndrome (increases risk of polyp development and cancer)
Diet/ environment- socioeconomic status, smoking, obesity, carcinogenic foods
What are the locations colorectal cancers are found in?
2/3 in descending colon and rectum
1/2 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 habit (diarrhoea)
Distal ileum obstruction (late sign)
Palpable mass (late sign)
How do left sided and sigmoid carcinoma colorectal cancer patients present?
PR (rectal) bleeding, mucus
Thin stool (late sign)
How do rectal carcinoma colorectal cancer patients present?
- PR bleeding, mucus
- Tenesmus- the feeling of needing to open bowels but nothing comes out when you try
- Anal, perineal, sacral pain (late sign)
What kind of a sign is bowel obstruction in colorectal cancers?
Late sign
What kind of signs show local invasion of colorectal cancers?
What kind of signs are these?
- Bladder symptoms
- Female genital tract symptoms
These are late signs
Where can colorectal cancers metastasise to (late sign) and how can these present?
- Liver (hepatic pain, jaundice)
- Lung (cough)
- Regional lymph nodes
- Peritoneum (Sister Mary Joseph nodule is metastasis in umbilicus)
What are the signs of primary colorectal cancer and how do we find these signs?
- Abdominal mass
- Abdominal tenderness and distension- large bowel obstruction
- DRE: most <12cm from dentate line and reached by examining finger
- Rigid sigmoidoscopy
What are the signs of metastasis and complications in colorectal cancer?
- Hepatomegaly
- Monophonic wheeze
- Bone pain
What investigations are performed for colorectal cancer?
Fecal occult blood
Blood tests
Colonoscopy
CT colonoscopy/ colonography
MRI pelvis
CT chest/ abdo/ pelvis
What are the 2 types of feral occult blood tests
- Guaiac test (Haemoccult)- based on pseudoperoxidase activity of haematin
- 40-80% sensitivity and 98% specificity
- Dietary restrictions- avoid red meat, melons, horse-radish, vitamin C and NSAIDs for 3 days before test
- FIT (faecal immunochemical test)- detects minute amounts of blood in faeces (faeces occult blood)
What 2 types of blood tests are conducted when diagnosing 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
Purpose of colonoscopy?
- Can visualise lesions <5mm
- Small polyps can be removed- reduced cancer incidence- see pic-pedunculated polyp (with a stalk) → we put wire around it and use heat to cut it and to close wound to prevent bleeding
Usually performed under sedation
How does CT colonoscopy/colonography compare with normal colonoscopy?
- Can visualise lesions >5mm
- No need for sedation
- Less invasive, better tolerated
- If lesions identified then patient needs colonoscopy for diagnosis
When is an MRI pelvis indicated?
If you have a tumour that you think is relatively advanced
What do you look at with pelvic MRI?
- Depth of invasion, mesorectal lymph node involvement- to see whether we can do an R0 resection (take all of cancer out with good margin)
- Help choose between preop chemoradiotherapy to reduce tumour size or go straight to surgery
- No bowel prep or sedation required
CT Chest/abdo/pelvis- why is this done?
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 surgery for colorectal cancer?
Put a stent in or use radio or chemo
a) What do you do with a right and transverse colon obstructing carcinoma?
b) Why do you have to be more careful with a left sided obstruction?
a)- Usually they don’t obstruct because there’s more leeway for carcinoma to expand
- If it is obstructing, we can resect and join up straight away with primary anastomosis because blood supply is good so it won’t leak
b)The blood supply on left colon isn’t as good
What is a Hartmann’s procedure?
Remove the tumour but then instead of joining proximal bowel and rectum, we bring proximal bowel up to skin and do a colostomy (leaving a stoma)- called a proximal end colostomy (LIF)
We can reverse in 6 months if patient is fine
What’s the difference between a stoma on the left or right side of a patient?
- left side means colostomy (large bowel)
- right side means ileostomy (small bowel)
What can you do with a left sided bowel obstruction?
Hartmann’s procedure
We can do a primary anastomosis (joining up proximal bowel and rectum)
- We would do an intraoperative bowel lavage with primary anastomosis
- However there’s a 10% chance of leak because the blood supply isn’t the bes
We can also put in a palliative stent
Study this pic of colonic bowel supply
What are the important right sided arteries in colon?
- Ileocolic
- Right colic
- Middle colic
What are the important left sided arteries in colon?
- Left colic
- When we get to pelvis, sigmoid arteries are important
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
What is a left hemicolectomy?
Resect left colon then anastomose remaining colon parts