Colorectal cancer Flashcards
Describe the incidence of colorectal cancer?
- Third most common cancer in the UK
- Second highest mortality
- Strongly associated with age
- Different types of inherited syndromes
Describe the aetiology of colorectal cancers?
- Originate from epithelial cells, most commonly adenocarcinoma
- Also lymphoma, carcinoid and sarcoma
- Normal mucosa -> colonic adenoma (polyps) -> invasive adenocarcinoma
- Genetic mutations implicating in colorectal cancer:
- APC
- HNPCC
Describe the APC mutation?
- Adenomatous polyposis coli
- Tumour suppressor gene
- Mutation causes growth of adenomatous tissue
- Associated with Familial Adenomatous Polyposis (FAP)
Describe the HNPCC mutation?
- Hereditary nonpolyposis colorectal cancer (HNPCC)
- DNA mismatch repair gene
- Mutation leads to defects in DNA repair
- Associated with Lynch syndrome
What are the risk factors for colorectal carcinoma?
- 75% are sporadic with no specific risk factors
- Potential risk factors:
- Increasing age
- Family history
- Inflammatory bowel disease
- Low dietary fibre, calcium, vitamin D
- Processed meat intake
- Smoking, alcohol
Clinical features of all colorectal cancers?
- Change in bowel habit
- Rectal bleeding
- Weight loss (usually metastatic disease)
- Abdominal pain
- Iron-deficiency anaemia
Specific clinical features of right-sided colon cancers?
- Abdominal pain
- Occult bleeding / anaemia
- Mass in right iliac fossa
- Often present late
Specific clinical features of left-sided colon cancers?
- Rectal bleeding
- Change in bowel habit
- Tenesmus
- Mass in left iliac fossa or on PR exam
What patients does NICE recommend be referred for urgen invesitgation of bowel cancer?
- >40 with unexplained weight loss and abdominal pain
- >50 with unexplained rectal bleeding
- >60 with IDA or change in bowel habit
- Positive occult blood screening test
Name some differentials for symptoms associated with colorectal cancer?
- Inflammatory bowel disease (20-40yrs old)
- Haemorrhoids
Describe the colorectal cancer screening process?
- Age 55
- Invited for one off colonoscopy
- Age 60-74
- Home testing kit every 2 years
- Usually faecal immunochemistry test (FIT)
- If positive, colonscopy is performed
- Age >74
- Request home testing kit every 2 years
Investigations into someone with a suspected colorectal carcinoma?
- FBC: microcytic anaemia, LFTs, clotting
- Carcinoembryonic antigen (CEA) tumour marker
- Colonscopy with biopsy (GOLD STANDARD)
- If colonoscopy is unsuitable: flexible sigmoidoscopy, CT colonography
After a diagnosis of colorectal cancer is made, how can the neoplasm be staged?
- CT CAP (for mets)
- MRI rectum (rectal cancers only)
- Assess depth of invasion
- Endo-anal US
- DUKES or TNM STAGING
How can disease progression be monitored in colorectal cancer?
Carcinoembryonic antigen (CEA) tumour marker
Describe TNM staging of colorectal cancer?
- T: depth of tumour into bowel wall
- N: extent of spread to local lymph nodes
- M: whether there are distant METs
Describe Dukes’ staging for colorectal cancer?
Describe the general management of someone with colorectal cancer?
- Discussion at a MDT
- Surgery +/- chemo + radiotherapy
- Regional colectomy followed by primary anastomosis or stoma formation
Describe the surgical management of caecal or ascending colon tumours?
- Right hemicolectomy
- Ileocolic, right coli and right branch of middle colic vessels are divided and removed with their mesenteries
Describe the management of a transverse colon tumour?
Extended right hemicolectomy
Describe the management of a descending colon tumour?
- Left hemicolectomy
- Left branch of middle colic vessels, inferior mesenteric vein and left colic vessels are divided and removed with their mesenteries
Describe the management of a sigmoid colon tumour?
- Sigmoidcolectomy
- IMA is fully dissected out with the tumour to ensure adequate margins
Describe the management of high rectal tumours?
- Anterior resection
- Leaves renal sphincter intact
Describe the management of a low rectal tumour?
- Abdominoperineal (AP) resection
- <5cm from the anus
- Excision of distal colon, rectum and anal sphincters
- Requires permanent colostomy
Describe the use of Hartmann’s procedure?
- Used in emergency bowel surgery
- Obstruction or perforation
- Complete resection of recto-sigmoid colon with formation of an end colostomy and closure of the rectal stump
Describe the palliative management of advanced colorectal cancers?
- Reduce cancer growth and symptom control
- Stoma formation
- Patients with acute obstruction
- Endoluminal stenting
- Relieve acute bowel obstruction in patients with left-sided tumours
- Stoma formation
