What is colorectal cancer?
What is colorectal cancer?
The colon and rectum make up the large intestine (or large bowel), which is part of the digestive system, also called the gastrointestinal (GI) system.
The colon is the longest part of the large intestine (the first 1.5-1.8 metres). It receives almost completely digested food from the caecum (a pouch within the abdominal cavity that is considered to be the beginning of the large intestine), absorbs water and nutrients, and passes waste (faeces) to the rectum.2
Most of the large intestine is made up of the colon, a muscular tube about 1.5-1.8 metres long.2
The rectum is the lowest 12-15cm of the large bowel, is relatively fixed in position behind the peritoneum (the tissue that lines the abdominal wall).
What is colorectal cancer
Most colorectal cancers start as a growth, called a polyp, on the inner lining of the colon or rectum.4
Over time (usually many years), some polyps can change into cancer. The chance of a polyp turning into cancer depends on the type of polyp.4 The different types of polyps are:4
- Adenomatous polyps (adenomas): these polyps sometimes change into cancer, and because of this, adenomas are called a pre-cancerous condition. There are three types of adenomas: tubular, villous, and tubulovillous.
- Hyperplastic polyps and inflammatory polyps: these polyps are more common, but in general they are not pre-cancerous. Some people with large (more than 1cm) hyperplastic polyps might need colorectal cancer screening with colonoscopy more often.
- Sessile serrated polyps (SSP) and traditional serrated adenomas (TSA): these polyps are often treated like adenomas because they have a higher risk of becoming cancerous.
When cancer forms in a polyp, it can grow into the wall of the colon or rectum. The walls of the colon and rectum are made up of multiple layers – the cancer starts in the innermost layer (the mucosa) and can grow outward through some or all the other layers.4
When cancer cells are in the wall, they can then grow into blood or lymph vessels. From there, they can travel to nearby lymph nodes or to other parts of the body.4
The stage (extent of spread) of a colorectal cancer depends on how deeply it grows into the wall and if it has spread outside the colon or rectum.
Causes of colorectal cancer
Some factors that increase the risk of colorectal cancer include:1,3,4
- Inherited genetic risk and family history
- Inflammatory bowel disease such as Crohn’s
- High red meat consumption, especially processed meats
- Diet low in fibre
- Being overweight or obese
- High alcohol consumption (≥4 drinks/day)5
- Having a previous diagnosis of colorectal cancer
- Having other disease such as Type II diabetes
Symptoms of colorectal cancer
Symptoms of colorectal cancer include:1,3
- Change in bowel habit including diarrhoea, constipation or the feeling of incomplete emptying
- Change in appearance of consistency of bowel movements such as watery stools
- Blood in stools
- Abdominal pain, bloating or cramping
- Anal or rectal pain
- A lump in the anus or rectum
- Weight loss
- Unexplained fatigue
- Tiredness and/or anaemia (pale complexion, weakness, and breathlessness)
Diagnosing your colorectal cancer
Diagnosing your colorectal cancer
Your doctor will discuss your specific symptoms with you. Tests to diagnose colorectal cancer include:1,3
Blood tests – to check if there are any signs that you are losing blood in your stools, and to check for red blood cell count (low red cell count is common in people with colorectal cancer).
Immunochemical faecal occult blood test (iFOBT) – you may have this test depending on your symptoms. This test involves you taking a stool sample at home. The sample is examined for traces of blood which can be an indicator of a polyp, cancer, or other bowel condition. It does not diagnose cancer, but if blood is detected your doctor will recommend further testing.
Colonoscopy – the most comprehensive test for colorectal cancer. This test examines the length of the large bowel with a camera inserted into the anus under anaesthetic. Any unusual tissues can be removed for further examination.
Flexible sigmoidoscopy – carried out in the same way as a colonoscopy, this test is used to examine the rectum and left side of the lower colon. Any unusual tissue can be removed for further examination.
CT scan – takes three-dimensional pictures of several organs at the same time, and can help doctors plan surgery, if required. It can also see if the cancer has spread.
MRI scan – produces detailed cross-sectional pictures of the body and can show the extent of any tumours.
PET scan – produces three-dimensional colour images that show where any cancers are in the body.
Treatment for colorectal cancer will depend on the location and extent of the cancer, whether the cancer can be removed with surgery, likely side effects of treatment and your overall health. Your doctors will discuss the treatment options with you. They may include:1,3
Radiation therapy for colorectal cancer
It is not common to use radiation therapy to treat colon cancer, but more common to treat rectal cancers.4
Radiation therapy is often used before surgery to help shrink a tumour and make it easier to remove. It may also be used after surgery if the tumour was attached to an internal organ or lining of the abdomen, to help ensure any cancer cells left behind are removed.1,4
Radiation destroys lesions and tumours in a targeted site in your body. Treatment is carefully planned, and with the developments in technology, very little harm is done to normal body tissue surrounding the tumour.6
You may have internal radiation therapy (brachytherapy) or external radiation, beamed from outside the body.
At GenesisCare you are getting the latest-generation VMAT intensity modulated radiation therapy including systems to improve image-guided radiation therapy, and surface-guided radiation therapy technologies.
Radiation therapy can be delivered independently or alongside chemotherapy or surgery. Your doctor will discuss your specific treatment plan with you.
Chemotherapy for colorectal cancer
Chemotherapy is medication that treats your cancer by disrupting the cell cycle. The drugs kill cancer cells, preventing them from dividing and spreading further.
Your treatment with GenesisCare
Your treatment with GenesisCare
A cancer diagnosis is life changing. Even before your initial encounter with us you will experience a wave of emotions. It’s natural to feel disbelief, anxiety, sadness, anger and loneliness. At GenesisCare we understand these emotions and strive to strengthen your confidence, settle your emotions, and create care experiences for the best possible outcomes.
Our care team know your name and get to know who you are as a person. We don’t want you to feel alone when you’re at GenesisCare. Your nursing team and oncology team are here to support you before, during and after your cancer treatment. We are here to guide you to get the support you need which may include a psychologist, exercise physiologist, physiotherapist and dietitian.
Please contact your local GenesisCare centre for more details on services available. View a list of our centres here.
General side effects:3
- Soreness and swelling around the treatment area
- Tiredness and lethargy for a few weeks after you finish
Specific side effects (depending on the area being treated):
- Digestive issues – reduced appetite, pain, discomfort or bloating
- Change in bowel habits
- Nausea or
Most of these side effects will ease shortly after treatment is finished. Your team will discuss any long-term considerations with you depending on the tumour type.
Whether you experience side effects and how severe they are, depends on the type and dose of drugs you are given and your reaction from one treatment cycle to the next.
- Most side-effects are short-term and can be managed
- They tend to gradually improve once treatment stops and the normal, healthy cells recover
You may worry about the side effects of chemotherapy. If you feel upset or anxious about how long treatment is taking or the impact of side effects, let your doctor or nurse know.
What can I do to help my treatment go smoothly?
- Get as much rest as possible
- Eat a wholefood, varied diet
- Appetite changes are common, and you may experience taste changes or nausea – help manage this by eating small, frequent snacks, avoiding smells that make you feel nauseous, eating foods that interest you rather than what you think you ‘should’ eat
- Keep up your water intake
- Reach out to support groups and others who have had
- Ask your team about topical treatments for skin if you are getting irritation or pain
- Stay out of the sun as much as possible throughout your treatment
- Record your side effects in a diary or journal
- Take some gentle exercise, such as walking, if you feel up to it. Light to moderate exercise can reduce treatment-related fatigue and improve
- It is important to acknowledge when you are fatigued, and rest when you need to. Plan your exercise for times in the day when you know you have more energy
- Ask for, and accept, help from family, friends and neighbours
- Be open with employers about your treatment and discuss flexible working options where needed
Other liver cancer information, resources and support services are available to assist you during your cancer journey. These include:
- Cancer Council. Bowel cancer. Available at: cancer.org.au/cancer-information/types-of-cancer/bowel-cancer. Accessed on: 15/07/21.
- Kahai P, et al. Anatomy, Abdomen and Pelvis, Large Intestine, 2020 StatPearls Pub, USA.
- Cancer Council Australia. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. Available at: cancer.org.au/australia/Guidelines:Colorectal_cancer#_ga=2.99481630.1470258732.1626230418-908501624.1616558293. Accessed on: 15/07/21.
- American Cancer Society. What is colorectal cancer? Available at: cancer.org/cancer/colon-rectal-cancer/about/what-is-colorectal-cancer.html. Accessed on: 15/07/21.
- Fedirko V et al. Annals of Onc 2011; 22:1958-1972.
- Li D, et al. Cancer Biol Med2014; 11(4):217-236.
- Cancer Council Australia. Radiation therapy. Available at: https://www.cancer.org.au/cancer-information/treatment/radiation-therapy. Accessed on: 15/07/21.
- Cancer Council Victoria. Chemotherapy side effects. Available at: https://www.cancervic.org.au/cancer-information/treatments/treatments-types/chemotherapy/side_effects_of_chemotherapy.html. Accessed on: 15/07/21.
Any procedure including treatments involving radiation carry risks, including skin irritation and associated pain. Before proceeding with a referral for treatment, patients should be advised to seek a second opinion from an appropriately qualified health practitioner. As in any medical procedure, patient experiences and outcomes will vary.
In Australia, we have more than 40 oncology centres in metro and regional Queensland, New South Wales, Victoria, South Australia, and Western Australia.
Our experienced, specialised doctors offer bespoke, dedicated care aiming to provide the best possible clinical outcomes.