Colorectal cancer Flashcards
What is the distribution between cancer in the colon and cancer in the rectal
2/3 colorectal cancer is located in the colonic
1/3 colorectal cancer located in the rectal
What is the aetiologies of colorectal cancer
Sporadic
Familial risk
Previous CRS
Inheritable conditions:
FAP, HNPCC
underlying inflammatory bowel condition
The greatest aetiology of Colon rectal cancer is Sporadic, what is the risk factors associated
Age
Male gender
Previous adenoma/CRC
Environmental influences
What are environmental influences that increase the risk of CRC
Diet Alcohol Obesity lack of exercise smoking Diabetes mellitus
What is the pathology of Colon rectal cancer
Arise from existing colorectal polyps
These are Benign adenomas that have a epithelial origin
Cell proliferation occurs, and activates oncogenes/loss of tumour suppressor genes/defective DNA repair pathway genes lead to larger cell growth that causes invasive adenocarcinoma that metastases resulting in leison of colon
What are the oncogenes activated to cause the dysplasia of polyps
K-ras
C-mc
What are the different types of histological polyps
Tubular
Villous
Interderminate tublovillous
What is the different morphologies of polyps
Pedunculated
Sessile
What does the high risk of lesion occurring depend upon
Size of polyps
Number of Polyps
degree of dysplasia
Villous architecture
What is the symptoms of colorectal cancer
Rectal bleeding
Altered bowel opening - diarrhoea
Iron deficiency anaemia
Weight loss/anorexia
What is the signs of colorectal cancer
Palpable rectal
Lower abdominal mass
What can occur in colorectal cancer is the tumour is stenosing
acute colonic obstruction
Whoa re more likely to have right sided colonic malignancy
Men
Non Menstruating women
What is the best option for investigating colorectal cancer
Colonoscopy
What is the benefits of colonoscopy
Therapeutic as well as diagnosic
can perform polypectomy
Followed up by tissue biopsy
What is the disadvantages to colonoscopy
Perforation and bleeding can occur if therapeutically used
Bowel preparation - disturb electrolyte balance
Sedation
What are 3 radiological imaging used of investigating colorectal cancer
Barium enema - not very actuate
CT colonography
- 3D virtual colonoscopy
CT abdo/pelvis
What is the disadvantages to radiological imaging
ionising radiation
no histology obtained
No therapeutic intervention
Bowel preparation
What imagery is used for staging investigations
CT scan (chest/abdomen/pelvis)
MRI
PET scan
Rectal endoscopic ultrasound
What is MRI scan good for diagnosing
rectal tumours
What is ABCD of Dukes Classification on colorectal cancer
A – Tumour confined to mucosa
B – Tumour extended through mucosa to muscle layer
C – Involvement of lymph nodes
D - Distant metastatic spread
What is the major treatment for colorectal cancer
Surgery
Laparotomy vs Laparoscopic
What is the surgical treatment for “cancer polyps” or when the tumour is confined to the mucosa (dukes a)
Endoscopic or local resection
What does the operative procedure depend upon
Site,
Size,
Stage of tumour
Why are lymph nodes removed in surgery
For histological analysis to see is metastases has occurred
If metastases has occurred what is the surgical procedure put in places
Partial hepatectomy - removal of liver
What is a permanent or temporary procedure put in places during surgery for colorectal cancer
Colostomy - stoma formation
When is chemotherapy treatment given in colorectal cancer
Adjuvant - after surgery
For palliative care of advanced disease
What stage in dukes classification is chemotherapy given
Duke C
If there is a positive Lymph node histology
Duke B
tumour extended though mucosa to muscle layer
What is the purpose of chemotherapy
Mop up micro-metastases
What is the agent used in chemotherapy
5-FU
fluorouracil
When is radiotherapy used in the treatment of colorectal cancer
Rectal cancer only
neoadjuvant - before surgery
+/-chemotharapy
What is the purpose of using radiotherapy as a neoadjuvant
to control primary tumour prior to surgery
possible shrink
When is colonic stenting used in colorectal cancer
Palliative care - preventing colonic obstruction
What are the two screening programmed for colorectal cancer
Average risk population
High risk groups
What is the aim of population screening
detect pre-malignant adenomas/ early cancers in the general population
What is the overall all the investigation for colorectal cancer populationg screening
Faecal occult blood test (FOBT) Faecal immunochemical test (FIT) Flexible Sigmoidoscopy Colonoscopy CT Colonography
What is the procedure put in places for the Scottish bowel screening programme
Everyone ages 50-74 years does a FOBT every two years
If screen positive referred for a colonoscopy
Who is screened as part of the high risk group
Heritable conditions
- FAP (familial adenomatous polyposis)
- HNPCC (hereditary non-polyposis colorectal cancer)
Inflammatory bowel disease
Familial risk
Previous adenomas/Colorectal cancer
What is FAP,
and what is its pathology
an autosomal dominant condition caused by mutation of APC gene on chromosome 5
that results in multiple adenomas throughout the colon
When is the high risk of malignant change in FAP
Early adulthood
by age 40 if left untreated
What is the screening procedure for FAP
annual colonoscopy from age 10-12
What usually occurs at age 16-25 years as a prophylactic procedure in FAP patients
proctocolectomy - removal or rectum and colon
What is the extracolonic manifestations of FAP
benign gastric fundic cystic hyperplastic - gastric polyps
duodenal adenomas -
Desmoid tumours - benign soft tissue tumour
CHRPE – congenital retinal hypertrophy of the pigment epithelia
What is the benefit of NSAIDS chemoprevetion
reduces polyp number and prevents recurrence of higher-grade adenomas in the retained rectal segment
What is HNPCC
autosomal dominant condition
that results in mutational DNA mismatch repair
causing micro-satellite instability
eg MLH1 and MSH2
Why is duodenal adenomas difficult to manage
Because surgery is more challenging
Where and when does HNPCC develop into colorectal cancer
Early onset colorectal cancer begins in your 40s and located at the right side
Where is other associated cancers located in HNPCC
endometrial, genitourinary, stomach, pancreas
What is needed for the diagnosis of HNPCC
clinical criteria
genetic testing
What is the screening protocol for HNPCC
From age 25 years
every 2 years colposcopy
(not as high protocol of FAP)
What is the screening portal for familial history of CRC
Previous - 5 year colonoscopy
High moderate risk 2-3 FDR
= 5 year colonoscopy at age 55 year on
Low moderate risk 1-2 FDR
Once only colonoscopy at 55 years
What is the screening protocol for IBD and what is it dependant on
10 years post diagnosis
Dependant on:
Duration, extent,
activity of inflammation
Presence of dysplasia
What does the screening protocol depend upon for previous adenomas
Number of polyps
Size of polyps
Degree of dysplasia
