Carcinoma of the Colon, Rectum and Anus Flashcards
What are the risk factors for colorectal carcinoma?
Family history Age Low dietary fibre/high fat diet (western) UC Smoking
What are the protective factors for colorectal carcinoma?
Fibre consumption
Exercise
HRT
Aspirin/NSAIDs
What is the genetic component contributing to colorectal carcinoma?
Familial adenomatous polyposis (FAP)
Hereditary non-polyposis colorectal cancer (HNPCC)
Describe FAP
Responsible for <1% of cancers
Due to tumour suppressor gene APC mutations
Describe HNPCC
Responsible for <5% of cancers
Germline mutations in mismatch repair genes
What cancer morphology is typical of colorectal carcinomas?
Adenocarcinomas (signet rings)
Where do most colorectal carcinomas occur?
Caecum & Ascending Colon - 15% Transverse Colon - 10% Descending Colon - 5% Sigmoid Colon - 25% Rectum - 45%
How do colorectal carcinomas first develop?
Polypoid mass w/ ulceration
Initial spread by bowel wall infiltration
How do colorectal carcinomas typically spread?
Through lymphatics/blood vessels
Metastasise to Liver primarily
Can spread transcoelomically
What are the common symptoms suggesting colorectal carcinoma?
Abdominal mass Abdominal pain Haemmorhage Perforation Fistula
How do R-sided colorectal carcinomas typically present?
Often asymptomatic
May present w/ IDA/weight loss
How do L-sided colorectal carcinomas typically present?
PR blood/mucus Altered bowel habit Tensemus Obstruction Mass on PR exam
How do anal carcinomas typically present?
Bleeding Pain Altered bowel habit Pruritis ani Masses/stricture
Describe Duke’s staging of colorectal carcinoma
Duke’s A - Tumours invade submucosa +/- muscularis propria
Duke’s B - Tumours invade past muscularis proria but no nodal involvement
Duke’s C - Regional lymph node involvement
Duke’s D - Distant metastases
What is the most common morphology of anal cancers?
SCC
Affect 1200 people/yr in the UK
What are the risk factors for anal cancer?
Anoreceptive sex
Syphillis infection
Anal warts/cervical cancer (HPV)
Immunosuppression
What is the pectinate line?
Embryological division b/w upper 2/3 and lower 1/3 of anal canal
What are the features of anal tumours above the pectinate line?
Columnar epithelium Lymph drainage to internal iliac nodes Portal venous drainage (hepatic mets) More common in women Worse prognosis
What are the features of anal tumours below the pectinate line?
Squamous epithelium Lymph drainage to superficial inguinal nodes Caval venous drainage (pulmonary mets) More common in men Better prognosis
What are the indications for a 2WW referral in pts >40?
Rectal bleeding/change in bowel habit >6w
Persistent rectal bleeding in pts >45
-w/ no obvious evidence of benign anal disease
IDA (Hb <10g/dl) w/o obvious cause
Palpable abdominal/PR mass
What investigations are appropriate in suspected colorectal carcinoma?
Bloods - FBC (microcytic anaemia?) LFTs (mets)
Colonoscopy +/- biopsy/polypectomy
CT chest, abdo, pelvis
Carcino-embryonic antigen (monitor)
What are the surgical options for treating colorectal carcinoma?
Right hemicolectomy Left hemicolectomy Sigmoid colectomy (high anterior) Anterior resection Abdomino-perineal resection Hartmann's procedure
What are the appropriate tumour sites for a right hemicolectomy?
Caecal
Ascending
Proximal transverse
What are the appropriate tumour sites for a left hemicolectomy?
Distal transverse
Descending
