Colorectal Cancer Flashcards
How common is colorectal cancer
Third most common cancers in the world
Which cells do colorectal cancers originate from
Epithelial cells lining the colon - simple columnar cells
What is the most common type of cancer in the colon
Adenocarcinoma- glandular tissue
What is the adenoma - carcinoma sequence
colorectal cancers develop via a progression of normal mucosa to colonic adenoma (colorectal ‘polyps’) to invasive adenocarcinoma
This is called adenoma - Carcinoma sequence
What is the conversion percentage from adenoma to adenocarcinoma
10%
What are colonic adenoma commonly referred to as.
Colonic polyps
Which gene mutations have been implicated in those who pre-dispose to colorectal cancer
Adenomatous polyposis coli - APC
- this is a tumor suppressor gene therefore mutation in this leads to abnormal tissue growth associated with FAP - Familial Adenomatous Polyposis
Hereditary nonpolyposis colorectal cancer ( HNPCC)
Outline in detail the adenoma - carcinoma sequence
Normal epithelium
Abnormal epithelium
Small adenoma
Large adenoma
Colonic carcinoma
what are the risk factors in developing colorectal cancer
75% sporadic - developing out of the blue - not associated with risk factors at all
Increasing age
FH
IBD
Low fibre diet
Smoking
High alcohol intake
What are the general clinical features of colorectal cancer
Change in bowel habit
Rectal bleeding
Weight loss
Abdo pain
Iron deficiency anaemia
What are the features of right sided colonic cancer
Abdo pain
Occult bleeding/anaemia
Mass in RIF
Presents late
Late change in bowel habit - more water in the faeces still
Fungating
What are the features of left sided colonic cancers
Rectal bleeding
Tenesmus
Mass in LIF / PR exam
Constipation - more water absorbed at this point
Early change in bowel habit
Less advanced at presentation
Stenosing - apple core sign
According to NICE when should patients be referred for urgent investigations of suspected bowel cancer
≥40yrs with unexplained weight loss and abdominal pain
≥50yrs with unexplained rectal bleeding
≥60yrs with iron‑deficiency anaemia or change in bowel habit
Positive occult blood screening test
What are the main differential diagnoses to consider when thinking about colorectal cancer
IBD
Internal haemorrhoids
To what ages is the colorectal cancer screening tool recommended
Men and women aged 60-75, this screening is offered every 2 years
What is used in the screening tool
Faecal immunochemistry test is most currently used
Also occult blood testing in faeces can also be used.
what happens if the samples from the screening tool test positive
Patient will be referred to have a colonoscopy
Which lab tests are ordered to investigate colorectal cancer
FBC - microcytic anaemia ( iron deficiency )
LFTs
COAG
Carcinoembryonic antigen ( CEA ) should not be used for diagnoses but can be used to monitor disease progression
What is the gold standard imaging modality used to investigate colorectal cancers
Colonoscopy with biopsy
If pt not suitable then flexible sigmoidoscopy/ CT colonography can be done
If gold standard picks up cancer, what further investigations are needed
CT CAP - for staging
CT colonogram
MRI rectum
Endo-anal USS - for rectal cancers
Which staging system is used for the staging of colorectal cancer
Dukes staging: stage A-D
A - confined beneath the muscularis propria
B - extension through muscularis propria
C - involvement of regional lymph nodes
D - distant mets
How would you manage colorectal cancer
Discuss at MDT
Surgery
Chemo and radiotherapy - important role in adjuvant and Neoadjuvant chemo
What is the main aim of surgery
Regional colectomy - take out tumor
Lymphatic drainage followed by anastomosis or stoma formation
What is a right hemicolectomy and how does this differ from extended right hemicolectomy
right hemicolectomy - caecum, ascending colon and proximal transverse colon removed
Extended right hemicolectomy - as above but also transverse colon until the splenic flexure is reached
https://www.bmj.com/content/bmj/366/bmj.l4561/F2.medium.jpg
When would you do a right hemicolectomy/ extended right hemicolectomy
Caecal tumors
Ascending colon tumors
Which arteries are clamped during a right hemicolectomy
Ileocolic, right colic and right branch of middle colic are clamped and removed with their mesenteries
What is a Left Hemicolectomy
From the splenic flexure to the sigmoid colon is removed
Which arteries have to be clamped for a Left Hemicolectomy
Left branch of middle colic
IMV
Left colic vessels
What is a sigmoidcolectomy
Taking out the sigmoid colon.
Done for taking out sigmoid cancers
What is Anterior Resection
Can be high or low
High - sigmoid colon plus 5 cm above anus
Low - sigmoid colon plus anus ( but not anal sphincter )
What is a Abdominoperineal (AP) Resection
Sigmoid, rectum and anus taken out
Usually done for low rectal tumours
Will result in a permanently colostomy as anal spinchter is also taken out
What is the hartmanns procedure
Used in emergency bowel surgery
Involves complete resection of the recto-sigmoid colon with the formation of a End colostomy and the closure of the rectal stump.
What chemotherapy options are available for patient with advanced colorectal cancer ( metastatic )
FOLFOX
Folinic acid
Flurouracil ( 5 -FU)
Oxaliplatin
When is radiotherapy used
Used in rectal cancer due to risk of damaging small bowel if used in colon cancer
What treatments are included in palliative care
Endoluminal Stenting
- used to relieve bowel obstruction ( cannot be done in rectal tumors due to feeling of tenesmus )
Stoma formation
- can be used to bypass obstruction
Resection of secondaries
- done with adjuvant chemo
