Colorectal Cancer Flashcards
Define colorectal cancer
majority of colorectal cancers are adenocarcinomas derived from epithelial cells
What percentage of colorectal cancers occur in each part?
66% of new colorectal cancers arise in the colon (43% in the proximal colon and 23% in the distal colon)
30% in rectum
What is the greatest risk factor for sporadic colorectal adenocarcinoma?
Increasing age
What are the key diagnostic factors for colorectal cancer?
Presence of risk factors Increasing age Rectal bleeding Change in bowel habit Rectal mas Anaemia
What are uncommon risk factors for colorectal cancer?
+ve family history
abdominal mass
What are some uncommon diagnostic factors for colorectal cancer?
Male sex Abdominal pain Weight loss Anorexia Abdominal distention Palpable lymph nodes
What are some strong risk factors for colorectal cancer?
Increasing age Adenomatous polyposis coli mutation Lynch syndrome MUTYH/MYH-associated polyposis Harmaromatous polyposis syndromes IBD Obesity
What are some weak diagnostic factors for colorectal cancer?
Acromegaly
Limited physical activity
Lack of dietary fibre
What are the first line investigations for colorectal cancer?
FBC Liver biochemistry Renal function Colonoscopy CT colonography Double contrast barium enema CT scan CAP
Why FBC for colorectal cancer?
6% - 10% patients with iron deficiency anaemia have colorectal cancer
Why do we do liver and renal function test?
Baseline in assessment of the patient and to assess for future treatments.
normal, often even when liver metastases present
When is a colonoscopy performed?
No clinical evidence of bowel obstruction
Sensitive
Allows for biopsy of suspicious lesion and removal of incidental polyps
What preparation is required for a biopsy?
Full bowel prep
Oral laxatives
To ensure clear views of the whole mucosa
What would a positive colorectal finding be on a colonoscopy?
Ulcerating or exophytic mucosal lesion that may narrow the bowel lumen
What to do the presenting symptoms of colorectal cancer depend on?
Size and location of the tumor
What are the presenting symptoms of left-sided colon and rectum?
Change in bowel habit
Rectal bleeding
Tenesmus
What is Tenesmus and why does it occur?
Due to space occupying tumour in the rectum
It is the sensation of incomplete emptying after defecation
What are the presenting symptoms when the right-sided colon is affected?
Presents later Anaemia symptoms Weigh loss Non-specific malaise Lower abdo pain (rare_
Why do 20% of tumours present as an Emergency? And how do they present?
Pain and distention due to:
Large bowel obstruction
Haemorrhage or peritonitis due to perforation
What are the signs of colorectal cancer on examination?
Anaemia
Abdominal mass
Low lying may be palpable on DRE
If metastatic: hepatomegaly, ascites
What might be seen in colorectal cancer on a double contrast barium enema?
‘Apple core’ strictures
What is the treatment to rectal cancer suitable for surgery?
Stage I low risk - local or radical excision
Stage II high risk - radical resection adj. pre-op radiotherapy +/- chemo
Stage II-III - radical resection + pre/post op chemo
OR
Total neoadjuvant therapy
Stage IV - surgical resection, locally ablative procedures, chemoradiotherapy
What is the treatment to rectal cancer not suitable for surgery?
Chemo
Adj. VEGF inhibitor or EGFR inhibitor
Adj. Stenting
2nd line
- Alt chemo/targeting therapy regimen
Adj. Stenting
