Colorectal Cancer Flashcards
Describe the risk factors for developing colorectal carcinoma?
Name protective factors for colorectal carcinoma?
Risk factors for colorectal are both environmental and genetic.
Genetic:
- FH
- FAP
- HNPCC
- UC
Environmental:
- Smoking
- Diets high in animal fats
- Low fibre diets
- Obesity
- Alcohol
- Age
Protective: HRT, exercise, diet high in fibre
Describe the most common sites for colorectal carcinoma?
The most common sites are the caecum, sigmoid colon and rectum.
- Caecal roughly 15%
- Transverse colon 10%
- Descending colon 5%
- Sigmoid roughly 25%
- Rectal roughly 45%
Describe the most common type of colorectal cancer and the common routes of invasion?
90% are adenocarcinoma. May initially be polyps.
Colorectal cancer spreads through direct invasion through the bowel wall. It is then locally invasive into lymph and liver, however it may present with metastases before the local growths become symptomatic.
The most common site of metastasis is the liver. Other sites include: lungs, brain and bone.
Describe how anal cancer differs to colorectal cancer?
- Clearly differs in site.
- More commonly it is a squamous cell carcinoma copared to adenocarcinomas in colorectal cancer.
- Risk factors differ: HPV, HIV, immune suppression, smoking, syphillis, anoreceptive sex.
- It is a much rarer malignancy.
- Spreads to liver (above dentate), and lung (below dentate)
What are the symptoms suggestive of colorectal cancer of the caecum?
Proximal (to splenic flexure, commonly caecal):
- Occult blood loss/ IDA
- Mass in RIF
- Weight loss
- Anorexia.
What are the symptoms suggestive of colorectal cancer of the sigmoid or rectum?
Left colon cancers (sigmoid):
- Colicky pain.
- Bowel obstruction
- Tenesmus
- Mass in LIF
- Diarrhoea
- Rectal bleeding (dark red).
Tend to be less advanced at presentation.
What are the symptoms suggestive of colorectal cancer of the anus?
Present with:
- Pruritis ani
- Bleeding
- Discharge
- Pain.
- Mass
Outline the staging system used to classify colorectal cancers and relate this to findings?
Staged with CT
Tumour/Nodes/Metastases
T 0-4 (4 penetrates visceral aka perforates causing peritonitis) N 0-2
M 0/1
Dukes ABCD
A: Invasion of the inner most lining of the bowel
B: Invasion through to the muscular layer of the bowel
C: Invasion to a local lymph node
D: Distant metastases
Grading:
1: well differentiated
2: moderately differentiated
3: poorly differntiated
Describe how you would investigate suspected colorectal cancer?
Bloods:
- FBC (IDA?), LFT (Mets?)
- Colonoscopy or flexi 2WW
If confirmed
- CT chest, abdo, pelvis
- MRI if rectal cancer
Outline the red flag symptoms which warrant a 2 week wait referral?
40 years or older:
- Unexplained weight loss + abdo pain
50 years or older:
- Unexplained rectal bleeding
60 years or older:
- IDA or change of bowel habit for 6 weeks or more
Any age:
- Any unexplained abdominal mass
- Any palpable rectal mass
- Occult blood in faeces
Describe the management of colorectal cancer?
Surgical resection + radiotherapy/chemotherapy.
Primary anastomoses can be made or a colostomy.
Do chemotherapy post surgery in dukes C/D
Describe the name of the surgery in each of the following scenarios, colorectal cancer of the; caecum, distal transverse/descending colon, sigmoid, high rectal?
Right hemicolectomy: for tumours in the caecum, ascending and proximal transverse colon.
Left hemicolectomy: Distal transverse/ descending colon.
Sigmoid colectomy: for tumours of the sigmoid colon.
Anterior resection: if in the low sigmoid or high rectum. Anastomosis is achieved at the first operation.
Abdomino-perineal (AP) resection: for tumours low in the rectum (less than approximately 8 cm from the anal canal). Permanent colostomy and removal of rectum and anus.
What is total mesorectal excision?
It is the concept of resecting up until the level of the levator ani muscles when performing an anterior resection of the middle or lower rectum.
In doing this it reduces local recurrence.
‘Low Anterior Resection’
Describe how patients are followed up after curative resection and adjuvant treatment?
Regular serum CEA* tests (3-6 monthly for 3 years)
At least 2 chest/abdo/pelvis CT scans in the 1st 3 years.
*Carcinoembryonic antigen (an antigen that is present in several cancers particularly colorectal ca.
Colonoscopy 1 year after, then every 5 years
Discuss what is meant by the term metachronus cancers?
It refers to having 2 primary cancers consecutively, common in colorectal cancer. (5%)
If undergoing surgery then need colonoscopy to look for additional lesions.
Describe the management of an obstructing colorectal cancer?
- A-E, fluids, catheter, bloods, FBC, U+E
- Analgesia
- NG tube decompression
- AXR and CXR
- CT to determine level of obstruction
- Gastrograffin follow through can show level of obstruction
Surgical resection is the ideal management.
Other options include emergency colonic stenting, this can be used as definitive management in palliative cases/those unfit for surgery.
Colonic stenting can also be used as a bridging procedure before surgery.
Outline how anal cancer prognosis varies depending on location?
Anal canal cancers are poorly differentiated and have a worse prognosis (more common in women)
dentate line inbetween
Anal margin cancers are well differentiated and have a better prognosis (more common in men)
Describe the management of anal cancers?
Stage 0 (just inner wall)
Local excision can be used for small well differentiated cancers of the anal margin not involving the sphincter.
Stage 1/2/3/4
Combined modality chemotherapy and radiotherapy are mostly used.
Chemotherapy drugs: 5-fluorouracil plus mitomycin C.
OR AP resection
What are the indications for surgery in anal cancers?
- Tumours that fail to respond to radiotherapy.
- Large tumours causing gastrointestinal obstruction.
- Small anal margin tumours without sphincter involvement.
What are the main polyposis conditions which predispose to colorectal cancer?
- Familial adenomatous polyposis (Gardner’s syndrome),
- Turcot’s syndrome
- Peutz-Jeghers syndrome
- Juvenile polyposis syndrome
