Colorectal Cancer Flashcards
Colorectal Neoplasia Naming
Benign = Adenoma Malignant = Adenocarcinoma
Types of Colorectal Polyps
Inflammatory
Hamartomatous
Metaplastic
Neoplastic (adenoma)
Adenoma - Carcinoma Sequence
The bigger the adenoma, the greater the risk of it developing cancer
APC is generally the first mutation (found in nearly all colorectal cancers)
Generally, then Kras, p53 and 18q
Genes Associated with Cancer
Oncogenes = Mutation causes gain of function. Excess cell growth and division
Tumour Supressor Genes = Mutation causes loss of function. Does not suppress cell growth and division
Pathology - Macroscopic Appearance
Polypoidal
Ulcerative
Annular
Common Sites of Colorectal Cancer
Commonly Rectum Sigmoid Colon Caecum Transverse Colon Rarely Descending Colon
Histology - Adenomas
Tubular = Predominantly tubular are unlikely to be malignant Villous = Predominantly violas are more likely to be malignant
Histology - Adenocarcinoma
Well differentiated = Lots of intracellular mucus
Moderately differentiated = Virtually lost all intracellular mucus
Poorly differentiated = Strands of highly undifferentiated cells
Dukes Staging
A = Cancer has not invaded through the muscle layer B = Cancer has invaded all the way through the muscle layer C = Lymph node invasion D = Distant metastases
Spread of Colorectal Cancer
Local = Adjacent structures Lymphatic = Pericolic or perivascular nodes Blood = Liver or lungs (MOST COMMON SITES) Transcoleomic = Peritoneal cavity
Lifestyle Factors
Protective =
EXERCISE
Vegetables
Fibre
Causative = OBESITY Red and processed meat Smoking Alcohol
Autosomal Dominant Inheritance
FAP =
Mutation in APC gene
Many many many adenomas
HNPCC =
Mutation in DNA mismatch repair
Predisposing Conditions
Adenomatous polyps
Ulcerative Colitis
Crohn’s Disease
Symptoms
Dependent on site
Generally larger tumours are more symptomatic
Rectal =
PR bleeding
Tenesmus
Sigmoid =
Pain
Change of bowel habit
PR bleeding
Caecum =
Anaemia
Clinical Findings
General =
Anaemia
Cachexia
Lymphadenopathy
Abdomen =
Mass
Hepatomegaly
Distension
Rectum =
Mass
Blood
NOTE = In most patients, you will not find any of these signs. If you do, they probably have advanced disease
Diagnosis of Primary Disease
Barium enema = sometimes isn’t very effective and shows very little
CT colography = gives much better definition
Sigmoidoscopy or Colonoscopy = GOLD STANDARD. Can see and biopsy the tumour
Faecal Occult Blood Testing
Guaiac = Turns blue in presence of blood
Immunochemical = Tests for presence and quantity of blood
Used in screening at lower sensitivity
Colorectal Cancer Screening
Participation = 30% reduction in death
No blood = negligible chance of colorectal cancer
Staging Investigations
CT - Lungs and Liver
MRI - Primary rectal cancer
Emergency Presentation
Obstruction = distension, constipation, pain, vomiting
Bleeding
Perforation
Treatment of Obstruction
Colostomy
Resection + colostomy
Resection + anastomosis
Stenting
Treatment
Surgery
Radiotherapy
Chemotherapy
Surgery for Colonic Cancer
Take out the affected part
E.g. right hemicolectomy, transverse colectomy, subtotal colectomy etc.
You must also removed all the draining lymph nodes
Surgery for Rectal Cancer
Abdomino-perineal excision = Leaves part of the rectum
Anterior resection = Rectum is removed and an ileostomy required
Radiotherapy for Rectal Cancer
Adjuvant =
Pre or post operative
Reduced local recurrence after rectal excision
Palliative =
Inoperable primary rectal cancer
Recurrent rectal cancer
Chemotherapy for Colorectal Cancer
Adjuvant for Stage C
For advanced disease
Keys to Improved Survival
Prevention = diet and lifestyle Early detection = heightened awareness and screening High quality surgery Appropriate use of RT and chemo New agents for advanced disease
