Colorectal tumours (GI) Flashcards
(41 cards)
What type of cancer are most colorectal tumours?
Adenocarcinomas of epithelial cells
What are the types of colorectal tumours? (3)
- sporadic (95%)
- hereditary non-polyposis colorectal carcinoma (HNPCC AKA Lynch syndrome, 5%) - most common inheritable form
- familial adenomatous polyposis (FAP, <1%)
Which parts of the colon do colorectal tumours occur in most?
- 43% proximal colon
- 23% distal colon
- 30% rectum
Which age group do colorectal tumours tend to affect?
65-74 years old
Describe the progression of colorectal tumours.
Normal colonic epithelium –> dysplastic adenomatous polyps –> invasive colorectal cancer
Describe the pathophysiology of colorectal tumours.
- inactivation of tumour suppressor genes –> DNA repair genes –> activation of oncogenes
- mostly sporadic mutations
- some due to mutation in adenomatous polyposis coli gene (APC) –> tumour suppressor gene inactivation –> uncontrolled division –> polyp
- single germline mutation in APC responsible for dominantly inherited syndrome (FAP)
How can metastatic spread of colorectal tumours to local lymph nodes occur? (3)
- enteric venous drainage to liver
- systemic blood to lungs
- less commonly to brain and bone
What are the (general) clinical features of colorectal tumours? (8)
- rectal bleeding
- change in bowel habit (increased frequency or looser stool)
- rectal mass
- iron deficiency anaemia signs e.g. fatigue, SOB, pallor
- abdominal pain (relieved on emptying bowels, pain when defecating)
- tenesmus
- FLAWS
- hepatomegaly (if liver mets)
What might you see on examination in colorectal tumours? (3)
- rectal mass
- palpable lymph nodes - advanced disease
- abdominal distension - advanced disease due to ascites/obstruction/hepatomegaly
What are the signs of right-sided colorectal tumours (caecum, ascending and transverse colon)? (3)
- melaena - dark blood in stool, may be occult
- IDA signs e.g. lethargy
- diarrhoea
What are the signs of left-sided colorectal tumours (splenic flexure, descending and sigmoid colon)? (3)
- changes in bowel habit (size, consistency, frequency)
- blood-streaked stools (mixed in)
- colicky abdominal pain (due to obstruction because of narrower lumen)
What are the signs of rectal tumours? (5)
- haematochezia (fresh, bright blood in stool)
- rectal pain
- tenesmus (urge to empty rectum/bladder)
- flatulence
- faecal incontinence
What are some risk factors for colorectal tumours? (10)
- age
- Fx
- FAP (adenomatous polyposis coli mutation) - inevitably develop colorectal tumours
- Lynch syndrome (AKA HNPCC)
- MYH-associated polyposis
- hamartomatous polyposis syndromes
- IBD (UC) - related to extent and duration
- obesity
- smoking
- alcohol
What are the first-line investigations for colorectal tumours? (4)
- FBC
- liver biochemistry/LFTs (liver mets)
- renal function
- colonoscopy
What test is gold-standard and diagnostic for colorectal tumours?
Colonoscopy (requiring laxatives day before surgery) and biopsy
(Can use flexible sigmoidoscopy/CT colonography if not available/suitable)
What does colonoscopy of colorectal tumours show?
Ulcerating or exophytic mucosal lesion that may narrow the bowel lumen
What would FBC show in colorectal tumours? (2)
- IDA - microcytic anaemia
- low ferritin in IDA
What other blood test can we do for colorectal tumours?
Tumour markers (CEA) to monitor disease progression
What is now being used more as a first-line investigation for colorectal tumours (NICE 2023 guidance change)?
Increased use of FIT testing, instead of always doing a colonoscopy first-line
What scan can we do in colorectal tumours?
CT CAP (CT chest, abdomen, pelvis) to look for metastases and carry out Dukes’ staging/classification
What is Dukes’ classification/staging of colorectal tumours (and 5-year survivial)?
- Dukes’ A: tumour confined to mucosA (95%)
- Dukes’ B: tumour invading Bowel wall (80%)
- Dukes’ C: lymph node metastases (65%)
- Dukes’ D: Distant metastases (5%, 20% if resectable)
What would a barium enema show in colorectal tumours?
Apple core lesion due to stricturing
Who do we do DRE on for colorectal tumours?
All patients with lower GI bleeding or red flags for colorectal cancer
How does screening for colorectal tumours work?
Faecal immunochemical test (FIT) screening every 2 years to all men and women ages 60-74 in England, 50-74 in Scotland
