Colorectal Cancer

• Colorectal cancer is the 4th most common cancer in the UK
• Risk factors for colorectal cancer include

  
  

  Family history of:

  • Bowel cancer
  • Familial adenomatous polyposis (FAP)
  • Lynch syndrome aka Hereditary nonpolyposis colorectal cancer (HNPCC)

  Other:

  • IBD
  • Older age
  • Diet - processed meat and low fibre
  • Obesity
  • Smoking
  • Alcohol
• Familial adenomatous polyposis (FAP) is an autosomal dominant condition involving mutated adenomatous polyposis coli (APC), a tumour suppressor gene.

  • Polyps (adenomas) form in the colon that can become cancerous.
  • Associated with earlier onset (before age 40)
  • Intervention: Panprotocolectomy, the removal of the colon to prevent the development of cancer.
• Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant condition that results from mutations in DNA mismatch repair (MMR) genes.
• Signs and symptoms of colorectal cancer include:

  • Change in bowel habits - more frequent, loose
  • Weight loss
  • Rectal bleeding - haematochezia
  • Abdominal pain
  • Iron deficieny anaemia - microcytic, low ferritin
  • Palpable abdominal mass
  • Can present acutely with bowel obstruction which is treated as a medical emergency
• The following cases would be referred for a 'two week wait':

  • Over 40 years with abdominal pain and unexplained weight loss
  • Over 50 years with unexplained rectal bleeding
  • Over 60 years with a change in bowel habit or iron deficiency anaemia
• Bowel cancer can present with iron deficiency anaemia as it causes microscopic bleeding. Patients get referred for both a gastroscopy and colonoscopy to rule out GI malignancy in these cases.
• Faecal immunochemical tests (FIT) assess for the amount of human haemaglobin in stool. Everyone aged 60-74 years old in England are asked to complete a FIT test at home every 2 years.
• Faecal occult blood (FOB) tests give can give false positives for detecting blood from red meats in stool rather than human haemaglobin
• The following groups of people are offered a regular colonoscopy as they fall in a high risk category for bowel cancer:

  1. FAP carriers
  2. HNPCC carriers
  3. Patients with IBD
• Colonoscopy is the gold standard investigation for patients with suspected bowel cancer because samples can be biopsied.
• Sigmoidoscopy is an endoscopy of the rectum and sigmoid colon, used in cases that only present with rectal bleeding
• CT colonography requires bowel prep and contrast to visualise the bowel. It is indicated for patients not fit for colonoscopy.
• Staging CT scan is offered in addition to colonoscopy. It involves CT thorax, abdomen and pelvis (CT TAP) to examine for metastasis.
• Carcinoembryonic antigen (CEA) is a tumour marker blood test used to predict relapse in patients previously treated for bowel cancer.
• T for Tumour:

  • TX – unable to assess size
  • T1 – submucosa involvement
  • T2 – involvement of muscularis propria (muscle layer)
  • T3 – involvement of the subserosa and serosa (outer layer), but not through the serosa
  • T4 – spread through the serosa (4a) reaching other tissues or organs (4b)
• N for Nodes:

  • NX – unable to assess nodes
  • N0 – no nodal spread
  • N1 – spread to 1-3 nodes
  • N2 – spread to more than 3 nodes
• M for Metastasis:

  • M0 – no metastasis
  • M1 – metastasis
• The treatment options for bowel cancer include:

  • Surgical resection
  • Chemotherapy
  • Radiotherapy 
  • Palliative care
• Right hemicolectomy involves removal of the caecum, ascending and proximal transverse colon.
• Left hemicolectomy involves removal of the distal transverse and descending colon.
• High anterior resection involves removing the sigmoid colon (may be called a sigmoid colectomy). 
• Low anterior resection involves removing the sigmoid colon and upper rectum but sparing the lower rectum and anus. 
• Abdomino-perineal resection (APR) involves removing the rectum and anus (plus or minus the sigmoid colon) and suturing over the anus. It leaves the patient with a permanent colostomy.
• Hartmann’s procedure is usually an emergency procedure that involves the removal of the rectosigmoid colon and creation of an colostomy. The rectal stump is sutured closed. The colostomy may be permanent or reversed at a later date. Common indications are acute obstruction by a tumour, or significant diverticular disease.
• Bowel Cancer Surgery

  
• Low anterior resection syndrome may occur after resection of a portion of bowel from the rectum, with anastomosis between the colon and rectum. It can result in a number of symptoms, including:

  • Urgency and frequency of bowel movements
  • Faecal incontinence
  • Difficulty controlling flatulence
• The follow-up investigations from bowel cancer surgery are

  • Serum carcinoembryonic antigen (CEA)
  • CT thorax, abdomen and pelvis