Colorectal Cancer (Bowel Cancer)

ColorectalTo do with the colon (big bowel) and rectum (the back passage; bum) an operation where the colon (bowel) is cut and joined to an opening (stoma) made in the stomach wall so that stools/waste products (poo) can move through the stoma into a bag on the outside of the body. cancerA disease where abnormal cells split without control and spread to other nearby body tissue and/or organs. Cancer cells can also spread to other parts of the body through the bloodstream and lymph systems., also known as bowelThe intestines (like a tube) that run between the stomach and anus (bum) and is made up of the small bowel (small intestine) and the large bowel (colon and rectum). (see ‘small intestine’; and ‘colon’ for more information). cancer, is a malignancy that develops in any portion of the colon
• The large intestine (also known as big bowel) which is the lower part of your digestive system from the end of the small intestine to the rectum (back passage; bum) which absorbs water from the food you eat and turns the leftover waste into faeces (stools; poo).
• Rectal cancer is found in the colon.
or rectum. Depending on where the cancer originates from, it may also be referred to as colon or rectal cancer.

The colon and rectum are towards the end of the body’s gastrointestinal (GI) tract, which is located in the abdomenstomach, stomach area, belly, tummy. The lower GI tract is divided into three separate areas: the small bowel, the large bowel and the anusEntry to the back passage; bum.. The small bowel receives food from the stomach and absorbs the nutrients from the food. It is comprised of three separate parts (the duodenum, jejunum and ileum). The food is then passed onto the large bowel, where water and salts are absorbed. The large bowel also consists of three parts (the caecum, colon and rectum). What is left over is turned into solid waste (faecesWaste product from the bowel through the back passage (bum), also called stools or poo. or stool), and is sent to the anus to be removed from the body.

Colorectal cancers develop in the large bowel. However, cancers of the small bowel and anus can rarely occur. For more information on these cancers, please refer to the Rare Cancers Australia Knowledgebase.

Colorectal cancer is more common in males, and are generally diagnosed in people over 50. However, anyone can develop this disease.

Types of Colorectal Cancer

Colorectal Cancers can be categorised based on the types of cells
• the smallest, living parts of the body. Cells work together to form or build the body
• a human is made up of millions of Cells
• Cells reproduce themselves to make sure a body stays working
• sometimes Cells can be abnormal or damaged and these can be cancer cells
(such as cancerous or pre-cancerous), as well as the size, shape and type of cells affected.

Pre-Cancerous Colorectal Growths

Most bowel cancers start as benignNot cancerous, can grow but will not spread to other body parts. growths – or polyps – on the wall or in the lining of the bowel. While polyps are usually harmless, they can become cancerous if they are of adenomatous origin. An adenoma (or adenomatous polypSmall lump/abnormal growth that grows inside your body such as the colon and very often sticks out/grows out of a stalk/stem like a tail.) is a non-cancerous or benign tumour that can be considered a pre-cursor to cancer if it is not treated.

Adenomatous polyps are often classified by their shape and size.

Tubular Adenomas

Tubular adenomas are the most common subtype of bowel polyp, and generally a small, tube or spiral shaped tumour. They generally form over many years, and may become cancerous if left untreated.

Villous Adenomas

Villous adenomas are generally larger and grow in a cauliflower shape with finger-like projections. These types of tumours are rare, and likely to become cancerous.

Tubulovillous Adenomas

Tubulovillous adenomas generally contain a mixture of tubular and villous adenoma growths. They vary in size and growth patterns, and may become cancerous if left untreated.

Hyperplastic Adenomas

Hyperplasia is defined as enlargement of an organ or structure due to excess cell production. These types of tumours are relatively common, and rarely become cancerous.

Inflammatory Adenomas

Inflammatory adenomas often occur in patients with an inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis. These types of growths rarely become cancerous.

Cancerous Colorectal Growths

Cancerous colorectal growths are often categorised by the types of cells the cancer originates from.

Adenocarcinomas

Adenocarcinomas are the most common type of colorectal cancer. These tumours originally begin as a benign adenoma formed from glandular cells, before developing into a malignantWhen a growth in a body part is cancerous. very serious and can grow and spread very quickly to other parts of the body. adenocarcinomaa cancer that grows in gland tissue. While adenocarcinomas can be aggressive, they can have a good prognosisTo predict how a disease/condition may progress and what the outcome might be. if caught early.

Splenic Flexure Cancer

Splenic flexure cancer is a rare form of colon cancer that develops in the splenic flexure, a sharp bend that connects the transverse colon (middle portion of the colon) to the descending colon (left portion of the colon that leads to the rectum). It is often diagnosed in the later stages of disease, and can be associated with bowel obstruction. Because of how rare splenic flexure cancer is, there has been limited research done into the risk factors and treatment of this disease.

Rare forms of Colorectal Cancers

These forms of colorectal cancers are very rare:

• Colorectal lymphomaKnown as a blood cancer, it is cancer of the white blood cells. (cancer originating from white bloodhello cells in the lymphatic systemIs part of the immune system whose job is to fight infections and also to filter and get rid of excess/extra body fluid. The lymphatic system is made up of many lymph nodes, spread across most of the body like a network/chain that are connected by very thin, lymph vessels (tube to carry fluids through).).
• Colorectal squamous cell carcinomas (cancer arising from squamous cells lining the GI tract).
• Colorectal neuroendocrine tumours (cancer arising from neuroendocrine cells).
• Gastrointestinal Stromal Tumours.

Treatment

If colorectal cancer is detected, it will be staged and graded based on size, metastasisKnown as secondary cancer, it grows/spreads from the original/ primary cancer. (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.

Cancers can be staged using the TNM staging system:

• T (tumour) indicates the size and depth of the tumour.
• N (nodes) indicates whether the cancer has spread to nearby lymphA clear fluid that moves through the body through the lymphatic system, carrying cells that fight infection. nodes.
• M (metastasis) indicates whether the cancer has spread to other parts of the body.

This system can also be used in combination with a numerical value, from stage 0-IV:

• Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
• Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
• Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localisedOnly to one area/place of body. cancer.
• Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
• Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advancedAt a late stage, far along or metastatic cancer.

Cancers can also be graded based on the rate of growth and how likely they are to spread:

• Grade
  • A score that tells how quickly a tumour might spread and grow by looking at how the abnormal cells and tissue look under a microscope.
  • Grade is not the same as stage.
  • Grading is different depending on the type of cancer.
  I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
• Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
• Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.

Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.

Treatment for colon and rectal cancers are treated differently, and often depend on several factors, including location, stage of disease and overall health.

Treatment options for colon cancer may include:

• Surgery, potentially including:
  • Right or left hemicolectomy (removal of right or left side of the colon).
  • Sigmoid colectomySurgery to cut away (resection) all or part of the colon (large intestine). (removal of the sigmoid colon).
  • Total colectomy (removal of entire colon).
  • Proctocolectomy (removal of the colon and rectum).
• Chemotherapy
  • a chemical drug treatment to kill or slow-growing cancer Cells
  • these drugs are called cytotoxic drugs
  .
• Clinical trials.
• Palliative careLessening pain without curing the disease..

Treatment options for rectal cancer may include:

• Surgery, potentially including:
  • High anterior resection (removal of the lower end of the colon and upper portion of the rectum).
  • Abdominoperineal resection or excisionTo cut out or remove by cutting. (APR or APE) (removal of the sigmoid colon, rectum and anus).
  • Ultra-low anterior resection (removal of the lower end of the colon and all of the rectum).
  • Colonic J-pouch (an internal pouch is created from the lining of the bowel, which acts as the rectum).
• Chemotherapy.
• Radiation therapy.
• Clinical trials.
• Palliative care.

For more information on the treatment options, please refer to the Rare Cancers Australia Treatment Options page.

Risk factors

While the cause of colorectal cancer remains unknown, the following factors may increase the likelihood of developing this disease:

• Being over 50 years old.
• Having colorectal polyps.
• Having certain diseases, such as Crohn’s disease or ulcerative colitis.
• Having a history of bowel, ovarian and/or endometrial cancer.
• Being obese.
• Having an unhealthy diet.
• Excess alcohol consumption.
• Having a history of smoking.
• Genetic mutations.
• Having a family history of bowel cancer.

Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.

Symptoms

In the early stages of colorectal cancer, the disease may be asymptomatic. As the cancer progresses, some of the following symptoms may appear:

• Changes in bowel movements, potentially including:
  • DiarrhoeaWhere watery or loose faeces (stools; poo) is frequently/often released discharged from the body. Also called ‘the runs’..
  • Constipation.
  • Feeling of incomplete bowel movement.
  • Thin bowel stools.
  • Blood in stools.
• Rectal bleeding.
• Abdominal pain, bloating and/or cramping.
• Anal and/or rectal pain.
• A lump in the anus or rectum.
• Unexplained weight loss.
• Unexplained fatigue.
• AnaemiaWhere the number of red blood cells have dropped. This can make people feel tired, breathless and unwell and affects how the body fights infection – potentially causing fatigue, weakness and/or weight loss.
• Changes in urinary habits, such as:
  • Blood in urine.
  • Frequent urination, especially at night.
  • Changes in urine colour – becoming dark, rusty or brown colour.

Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.

Diagnosis/diagnosing

If your doctor suspects you have a colorectal cancer, they may order the following tests to confirm the diagnosisUsing medical test results, identify and name a disease and/or condition. and refer you to a specialist for treatment.

Physical examination

Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they will examine your body (more specifically, around the abdomen) to check for any abnormalities. They may also perform a digital rectal examination (DREDigital rectal exam, meaning to use a finger to probe inside the anus (bum; bottom; back passage) to examine it (to find cancer.), which is an exam conducted by a urologist (a doctor specializing in issues pertaining to the kidneys, bladderA small, elastic/muscle type sac/bag in the body, where urine (wee) is stored for urinating/weeing. Is found in the lower abdomen/belly area., prostate, and male reproductive system). In this exam, the doctor will insert a finger (or ‘digit’) into your rectum to feel the anus. If it feels hard or is an odd shape, further testing may be required.

Blood tests

Blood tests are used to assessTo measure, look at and learn from. overall health and detect any abnormalities. Some of these tests may include:

• General blood test to assess overall health.
• Full blood countA test that counts red blood cells, white blood cells and platelets in the blood., which measure the levels of red blood cells, white blood cells and plateletsSmall blood cells (shaped like plates) whose job it is to come together in a group(s) or clump(s) to stop bleeding when you are injured or cut..
• Liver function test.
• Immunochemical faecal occult blood test (iFOBT).
• Blood chemistry and/or blood hormoneA chemical made in different body parts/organs that is sent out to other parts of the body through the bloodstream. Hormones watch over and help control how other cells or organs act. studies, which analyse the levels of certain hormones and other substances in the blood.
• CEA blood test.

Imaging tests

The doctor will take images of your body using magnetic resonance imagingTaking images/photos of inside body parts using magnet rather than x-ray. (MRITaking images/photos of inside body parts using magnet rather than x-ray.), a computed tomography scan (CT scanA 3-D (three dimensional) x-ray pictures that gives more information than a normal x-ray.), CT colonography and/or positron emission tomography (PET scanA test that uses a radioactive drug to show a picture of how your tissues and organs are working. Also known as a positron emission tomography scan.), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and look for signs of metastasis.

Colonoscopy

A colonoscopyTo look at the colon (big bowel) with a small flexible camera tube (called an endoscope) through the rectum (back passage; bum). is the main diagnostic test used for colorectal cancers. This procedure examines the lining of the entire large bowel, and can detect if any polyps or abnormal tissue are present. Your doctor will insert a long, flexible tube with a light attached (colonoscope) through your anus, rectum and colon while you are under an anaestheticA drug used to get rid of or reduce the feeling of pain by putting you to sleep. Carbon dioxide or air may be pumped through the colonoscope for better visualisation of the bowel.

Flexible Sigmoidoscopy

A flexible sigmoidoscopy is similar to a colonoscopy; however, this procedure only examines the rectum and lower portion of the colon. The instrument passed through the anus is shorter, and called a sigmoidoscope.

Biopsy

Once the location(s) of the cancer has been identified, the doctor will perform a biopsyTo take a small piece of body tissue and test it in a laboratory. to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells. This can be done by a fine needle aspiration (FNA) or a core needle biopsy (CNB).

References

• Bowel Cancer Australia
• Cancer Council Australia
• GI Cancer Institute
• NCBI - Splenic Flexure Cancer