- Colorectal cancer is second commonest cancer causing death in the UK
- 20,000 new cases per year in UK - 40% rectal and 60% colonic
- 3% patients present with more than one tumour (=synchronous tumours)
- A previous colonic neoplasm increases the risk of a second tumour (=metachronous tumour)
- Some cases are hereditary
- Most related to environmental factors - dietary red fat and animal fat
Adenoma - carcinoma sequence
- Of all adenomas - 70% tubular, 10% villous and 20% tubulovillous
- Most cancers believed to arise within pre-existing adenomas
- Risk of cancer greatest in villous adenoma
- Series of mutations results in epithelial changes from normality, through dysplasia to invasion
- Important genes - APC, DCC, k-ras, p53.
- Right-sided lesions present with
- Iron deficiency anaemia due occult GI Blood loss
- Weight loss
- Right iliac fossa mass
- Left-sided lesions present with
- Abdominal pain
- Alteration in bowel habit
- Rectal bleeding
- 40% of cancers present as a surgical emergency with either obstruction or perforation
- Emergency presentation is associated with a poorer outcome
Picture supplied by Mr N P J Cripps, Consultant Colorectal Surgeon, Chichester, United Kingdom
Picture provided by Mr David Anderson, St John's Hospital, Livingston, Scotland
- In elective cases diagnosis can be confirmed by a combination of:
- Rigid sigmoidoscopy
- Flexible sigmoidoscopy
- Double contrast barium enema
- In patients presenting with large bowel obstruction single contrast enema (after rigid sigmoidoscopy) is the
investigation of choice
- Any surgical resection requires 5 cm proximal and 2 cm distal clearance for colonic lesions
- 1 cm distal clearance of rectal lesions adequate if mesorectum resected
- Radial margin should be histopathologically free of tumour if possible
- Lymph node resection should be performed to the origin of the feeding vessel
- En Bloc resection of adherent tumours should be performed
- The value of a 'no-touch' techniques remains unproven
- Depending on site of lesion surgical options are:
- Caecum, ascending colon, hepatic flexure – Right hemicolectomy
- Transverse colon – Extended right hemicolectomy
- Splenic flexure, descending colon – Left hemicolectomy
- Sigmoid colon – High anterior resection
- Upper rectum – Anterior resection
- Consider defunctioning loop ileostomy is anastomosis <12 cm from anal margin
- Lower rectum – Abdomino-perineal resection
- Small lower rectal cancers may be resectable by transanal microsurgery
- Laparoscopic surgery is unproven
- Early studies raised concerns about port site recurrence
- Recent studies suggest equivalent overall and disease-free survival
Surgery for upper rectal cancers
- Risk of local recurrence reduced by performing total mesorectal excision (TME)
- Pelvic peritoneum and lateral ligaments divides
- Plane between visceral (rectum, mesorectum) and somatic structures dissected
- Middle rectal vessels divided laterally
- Rectal stump washed out with cytocidal fluid (water, Betadine) from below.
Picture provided by Prof Ian Bradford, Prince of Wales Hospital, Shatin, Hong Kong
- Developed by Cuthbert Duke in 1932 for rectal cancers
- Dukes staging of colorectal cancer
- Stage A - Tumour confined to the mucosa
- Stage B - Tumour infiltrating through muscle
- Stage C - Lymph node metastases present
- Five year survival - 90%, 70% and 30% for Stages A, B and C respectively
- In patients with rectal cancer 50% undergoing curative resection develop local recurrence
- Median survival with local recurrence is less than one year
- Risk factors for local recurrence include:
- Local extent of tumour
- Nodal involvement
- Circumferential margin status
- Risk of local recurrence can be reduced by radiotherapy
- Can be given either preoperatively or postoperatively
- Preoperative radiotherapy given as short course immediately prior to surgery
- Reduces local recurrence
- Increases time to recurrence
- Improves 5-year survival
- Combination chemotherapy and radiotherapy may produce better outcome
- Improves survival in Duke's C tumours
- Not required in Duke's A tumours which already have a good prognosis
- Role in Duke's B tumours remains to be defined
- Currently being investigated in the QUASAR (Quick and Simple and Reliable) trial
- Results of QUASAR study to date have shown
- 5FU and folinic acid is effective as adjuvant therapy
- High dose folinic acid rescue confers no additional benefit
- The use of levimasole confers no additional benefit
Colorectal cancer screening
- Screening for colorectal cancer can be divided into two categories
- Screening of high risk groups
- Population screening
Screening of high risk groups
- This includes
- Patients with family history
- Sporadic adenomatous polyps
- Inflammatory bowel disease
- Definition of the high risk group is difficult
- High risk patients should undergo colonoscopy at approximately 50 years
- Patients with family history of FAP or HNPCC should undergo genetic testing
- If mutation present should undergo intensive colonoscopic screening from adolescence
- The role of screening is currently being investigated by either
- Faecal occult blood testing
- Nottingham study has recruited over 150,000 patients
- 75,250 underwent biennial FOB testing
- Resulted in 1774 colonoscopies
- Seven complications occurred requiring operations in 6 patients
- No difference identified in stage of presentation in screened group
- Survival in screened group was significantly improved
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