Colorectal carcinoma

  • 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.

Clinical presentation

  • 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

A low rectal carcinoma

Picture supplied by Mr N P J Cripps, Consultant Colorectal Surgeon, Chichester, United Kingdom

Intraoperative appearance of caecal carcinoma

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
    • Colonoscopy
    • Double contrast barium enema
  • In patients presenting with large bowel obstruction single contrast enema (after rigid sigmoidoscopy) is the investigation of choice

Double contrast barium enema showing an apple-core stricture

Endoscopic apperance of sigmoid carcinoma

Surgical options

  • 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

Anatomy of the mesorectum

  • Middle rectal vessels divided laterally
  • Rectal stump washed out with cytocidal fluid (water, Betadine) from below.

Total mesorectal operative specimen

Picture provided by Prof Ian Bradford, Prince of Wales Hospital, Shatin, Hong Kong

Dukes Classification

  • Developed by Cuthbert Duke in 1932 for rectal cancers
  • Dukes staging of colorectal cancer

Duke's stageing 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

Adjuvant radiotherapy

  • 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

Adjuvant chemotherapy

  • 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

Population screening

  • The role of screening is currently being investigated by either
    • Faecal occult blood testing
    • Colonoscopy
  • 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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