cancer- colorectal

Question 1

what is colorectal cancer

Answer 1

also referred to as bowel, colon or rectal cancer

• Cancer derived from the lining of the large intestine
• usually start as pre-cancerous adenomatous polyps which can then form adenocarcinomas

Question 2

aetiology of colorectal cancer

Answer 2

• No known exact cause
• Genetic and environmental links
• Family history of bowel cancer or polyps
• Gene mutations lead to a significant increase in chance of developing colon cancer
• Increased risk with inflammatory bowel disease
• High red meat consumption, especially processed meats
• Overweight or obese
• Diabetes
• High alcohol consumption
• Smoking
• Radiation Therapy treatment

Question 3

epidemiology of colorectal cancer

Answer 3

• 16000 new cases diagnosed every year
• 11% of total cancers
• 3rd most prevalent cancer
• More prevalent in males (55%)
• 5600 deaths per year (2nd most common cancer cause)
• 5 year survival rate approx. 70%
• Risk of developing colon cancer increases with age
• Most colon cancers develop after the age of 50
• More prevalent in remote and rural areas (5% higher)
• More prevalent amongst low socioeconomic groups (28% higher)

Question 4

signs and symptoms of colorectal cancer

Answer 4

• Change in bowel habit (diarrhoea, constipation)
• Feeling of incomplete emptying
• Thin bowel movements
• Blood in the stools
• Abdominal pain, bloating or cramping
• Anal or rectal pain
• Lump in the anus or rectum
• Weight loss
• Fatigue
• Unexplained anaemia (low haemoglobin in blood)

Question 5

what diagnostic tests used when diagnosing colorectal cancer

Answer 5

• Faecal Occult Blood Test (FOBT)
• Microscopic blood in stool
• Blood test looking for anaemia
• Physical Examination
• If highly suspicious of Colorectal Cancer
• Digital examination – Colonoscopy / Sigmoidoscopy
• Diagnostic Imaging Tests
• Biopsy of tissue sample with microscopic evaluation

Question 6

what is a colonoscopy and when is it used

Answer 6

• Recommended for patients between 50 and 74 as a routine screening tool
• Patients with a significant suspicion of Bowel Cancer
• Flexible fibre optic camera with light
• Visualise the entire lining of the colon and rectum
• Looking for cancerous growths, polyps, inflammation and other pathologies
• Capability to pass other tools through the scope. (biopsy / diathermy)
• Sigmoidoscopy is a limited scope of the rectum and sigmoid colon

Question 7

what medical imaging tests are used for colorectal cancer

Answer 7

xray/fluoroscopy
CT
MRI
NM
US

Question 8

what is x-ray/fluoroscopy used for when imaging colorectal cancer

Answer 8

• Barium enema: traditional method of diagnosis of bowel cancer
• Patient bowel prep to clear colon of faecal material
• Involves the insertion of a plastic tube into the rectum
• Air and barium used to fill and dilate the colon
• Lines wall of bowel allowing it to be visualised on fluoroscopy and plain film x-ray
• Test now largely superseded by other diagnostic tests
• Occasionally still used due to patient compatibility and availability
• Accurate test for cancer but limited in polyp detection
• X-rays may also be taken to establish the presence of metastases (e.g. CXR)
• Used to follow up associated issues (e.g. obstruction)

Question 9

what is CT used for when imaging colorectal cancer

Answer 9

• Commonly used modality for investigation of suspected abdominal pathology
• Standard CT Abdomen is insensitive to small colorectal masses
• Has the ability to identify other complicating abdominal pathologies such as fistulae, obstruction and perforation
• Most commonly used modality in the staging of colorectal cancer
• Accuracy of diagnosis can be increased through dedicated CT Colonography study
• Scan requires dedicated prep and inflation of the colon with air
• Seen as a viable alternative to Colonoscopy in high risk patient groups or occasions where a colonoscopy has failed
• Dedicated software is required to obtain some of the images

Question 10

what is MRI used for when imaging colorectal cancer

Answer 10

• Increasing role in the diagnosis of rectal cancer
• Important modality in the staging of rectal cancer
• Increased contrast resolution allows for more accurate evaluation of localised spread and define boarders of the tumour
• Allows visualisation of extension into meso-rectal fat
• Identify spread to local lymph nodes
• Potentially helpful in identification of liver metastases
• Used in the evaluation of tumour recurrence

Question 11

what is NM used for when imaging colorectal cancer

Answer 11

• Not commonly utilised in diagnostic pathway
• Bowel cancer not commonly metastasising to bone
• PET can be used as alternative investigation in evaluating presence of distant mets (commonly lung and liver)
• PET has high sensitivity in the evaluation of tumour recurrence
• Differentiates between recurrent tumour and scar tissue better than CT alone
• Used in the evaluation of therapeutic response

Question 12

what is US used for when imaging colorectal cancer

Answer 12

• Not associated with the diagnosis of Rectal Ca
• Potential use in evaluation of metastases (particularly liver)
• Occasional use for staging of rectal tumours using endorectal probe (usually MRI contraindicated)

Question 13

what is the staging process for colorectal cancer

Answer 13

-Ascertain tumour size, location and spread
Use TMN system
-Tumour (T): Has the tumour grown into the wall or the colon or rectum? How many layers?
-Node (N): Has the tumour spread to the lymph nodes? If so, where and how many?
-Metastasis (M): Has the cancer metastasized to other parts of the body? If so, where and how much?

Question 14

what is the T score of cancer staging

Answer 14

• Describe how deeply the primary tumour has grown into the bowel lining
• T0: There is no evidence of cancer in the colon or rectum
• Tis: Refers to carcinoma in situ. Cancer cells are found in the top layers lining the inside of the colon or rectum
• T1: The tumour has grown into the submucosa, which is the layer of tissue underneath the mucosa or lining of the colon
• T2: The tumour has grown deeper into the muscular layer that contracts to force along the contents of the intestines
• T3: The tumour has grown through the muscular layer and into the connective tissue beneath the outer layer of some parts of the large intestine, or it has grown into tissues surrounding the colon or rectum
• T4a: The tumour has grown into the surface of the visceral peritoneum, which means it has grown through all layers of the colon
• T4b: The tumour has grown into or has attached to other organs or structures

Question 15

What is the N score of cancer staging

Answer 15

• The ‘N’ in the TNM system stands for lymph nodes
• Lymph nodes near the colon and rectum are called regional lymph nodes
• All others are distant lymph nodes that are found in other parts of the body
• N0: There is no spread to regional lymph nodes
• N1a: There are tumour cells found in 1 regional lymph node
• N1b: There are tumour cells found in 2 to 3 regional lymph nodes
• N1c: There are nodules made up of tumour cells found in the structures near the colon that do not appear to be lymph nodes
• N2a: There are tumour cells found in 4 to 6 regional lymph nodes
• N2b: There are tumour cells found in 7 or more regional lymph nodes

Question 16

what is the M score of cancer staging

Answer 16

• The ‘M’ in the TNM system describes cancer that has spread to other parts of the body
• Common sites of spread for Colorectal cancer is the Liver and lungs
• M0: The disease has not spread to a distant part of the body
• M1a: The cancer has spread to 1 other part of the body beyond the colon or rectum, but not to distant parts of the peritoneum (the lining of the abdominal cavity)
• M1b: The cancer has spread to more than 1 part of the body other than the colon or rectum, but not to distant parts of the peritoneum
• M1c: The cancer has spread to distant parts of the peritoneum, and may or may not have spread to another part of the body beyond the colon or rectum

Question 17

what is stage 0 of cancer staging

Answer 17

• Stage 0 is also called carcinoma in situ
• Abnormal cells are found in the mucosa (innermost layer) of the bowel wall
• These abnormal cells may become cancer and spread

Question 18

what is stage 1 of cancer staging

Answer 18

• The has spread to the submucosa (T1) or grown into the muscular layer (T2)
• It has not spread into nearby tissue or lymph nodes (N0)
• No distant metastases (M0)

Question 19

what is stage 2 of cancer staging

Answer 19

• Stage 2 bowel cancer is divided into stage 2A, stage 2B, and stage 2C
• Stage 2A: Cancer has spread through the muscle layer of the bowel wall to outermost layer) of the bowel wall (T3). It has not reached nearby organs and has not spread to nearby lymph nodes (N0) or to distant sites (M0)
• Stage 2B: Cancer has spread through the outermost layer of the bowel wall but has not grown into other nearby tissues or organs (T4a). It has not yet spread to nearby lymph nodes (N0) or to distant sites (M0)
• Stage 2C: Cancer has spread through the outermost layer of the bowel wall and has grown into other nearby tissues or organs (T4b). It has not yet spread to nearby lymph nodes (N0) or to distant sites (M0)

Question 20

what is stage 3 of cancer staging

Answer 20

• Stage 3 bowel cancer is divided into stage 3A, 3B, and 3C
• Stage 3A: Cancer has grown through the mucosa into the submucosa (T1) or muscle layer (T2). It has spread to nearby lymph nodes or into areas of fat near the lymph nodes
• Stage 3B: Cancer has grown into the muscular layer to the outer layers and perhaps invading peritoneum. Spread to lymph nodes (usually multiple)
• Stage 3C: Cancer has grown through the Bowel wall, may or may not involve nearby organs. Spread to multiple lymph nodes
• All Stage 3 cancers have not spread to distant sites (M0)

Question 21

what is stage 4 of cancer staging

Answer 21

• Also known as metastatic, advanced or secondary bowel cancer
• Stage 4 colon cancer is divided into stage 4A, 4B and 4C
• All stage 4 cancers: The cancer may or may not have grown through the bowel wall. It might or might not have spread to nearby lymph nodes
• Stage 4A: The cancer has spread to 1 distant organ or distant set of lymph nodes, but not to distant parts of the peritoneum
• Stage 4B: The cancer has spread to more than 1 distant organ or distant set of lymph nodes, but not to distant parts of the peritoneum
• Stage 4C: The cancer has spread to distant parts of the peritoneum, and may or may not have spread to distant organs or lymph nodes

Question 22

what are treatment options for colorectal cancer

Answer 22

surgery
RT
chemotherapy

Question 23

why is surgery used as a treatment option for colorectal cancer and what does it do

Answer 23

• The aim of surgery is to remove as much of the cancer as possible and nearby lymph nodes
• Small early cancers can be removed via colonoscopy or keyhole surgery
• More advanced cancer requires an open operation to remove cancerous bowel and nearby lymph nodes
• Removal of a section of bowel is called a colectomy
• If bowel is reattached to itself its call an anastomosis
• Sometimes colon attached to the skin (colostomy)
• Opening is called a stoma which has a bag attached to collect faeces

Question 24

why is chemotherapy used as a treatment option for colorectal cancer and what does it do

Answer 24

• Recommended if cancer has spread outside of the bowel to other areas of the body
• Can be utilised pre surgery to shrink the size of the tumour and bake it easier to remove
• After surgery chemotherapy will be utilised to kill any remaining cancer cells
• This usually takes place around 8 weeks post-surgery to allow the patient to recover from the operation
• If the cancer has spread to other organs, such as the liver or lungs, chemotherapy may be used either to shrink the tumours or to reduce symptoms and make the patient more comfortable
• Common side effects include tiredness, nausea, vomiting, diarrhoea, ulcers, loss of appetite, taste and smell, sore hands and feet, hair loss and an increased susceptibility to infection

Question 25

why is RT used as a treatment option for colorectal cancer and what does it do

Answer 25

• Targeted at cancer cells while minimising dose to healthy tissue
• Used frequently in the treatment of rectal cancer but not common with colon cancer
• Often combined with chemo as this makes cancer cells more susceptible to radiation
• The combination of these two treatments will make the tumour a small as possible prior to surgical removal
• This makes surgical removal easier and reduces the risk of recurrence
• Common side effects include tiredness, Bowel and bladder inflammation, diarrhoea, constipation or incontinence
• Radiation therapy can cause the skin or internal tissue fibrosis
• It can also affect fertility and sexual function
• RT course will usually run for 5-6 weeks

Question 26

what are alternative treatment options for colorectal cancer?

Answer 26

• Targeted drug therapy stop specific cell growth
• Thermal Ablation
• Selective internal radiation therapy
• Stereotactic body radiation therapy
• Palliative Treatment