Rectum Cancer Risk Factors

The symptoms of rectal cancer may be similar to those of other bowel diseases, like ulcerative colitis, Crohn’s disease or even colon or colorectal cancers. Often there are no early symptoms of rectal cancer. However, as the cancer develops, rectal cancer symptoms may become more persistent and severe.

Whereas, people with an inflammatory bowel disease (IBD), like ulcerative colitis or Crohn’s disease, may experience periods of remission where the symptoms subside.

Rectal cancer signs

The development of tumors in the rectum or anal canal may change the consistency, shape or frequency of bowel movements.

The severity of the symptoms may increase or more symptoms might arise as the cancer spreads throughout the rectum or into the colon.

Rectal bleeding may make the stool bright red. A bleeding tumor may also change the color of the stools, sometimes making the stool very dark or tarry looking.

Rectal cancer signs related to bowel habit changes may include:

  • Diarrhea
  • Constipation
  • Not being able to completely empty the bowel
  • Change in the size or shape of stools (narrower than usual)
  • Bloody stool (either bright red or very dark)

General rectal cancer symptoms

Early stages of rectal cancer may have no symptoms. However, more systemic (body-wide) changes may result as the tumor goes deeper into the layers of tissues lining the rectum or if the cancer spreads (metastasizes) throughout the body.

Generalized symptoms of rectal cancer may include:

  • Pain in the rectum
  • Abdominal pain or discomfort
  • More frequent gas pains or stomach cramps
  • Feeling bloated or full
  • Change in appetite
  • Unintended weight loss
  • Fatigue or tiredness

There are several screening methods available that can detect polyps or cancer. A screening may make it possible to find the cancer before symptoms appear.

Symptoms of rectal cancer

The symptoms of rectal cancer include:

  • A change in previous bowel habits, such as constipation or diarrhoea
  • Urgency to pass bowel motions
  • A sensation that the bowel isn’t empty after going to the toilet
  • Bleeding from the anus
  • Abdominal pain.

Risk factors for rectal cancer

  • Factors that may increase a person’s risk of rectal cancer include:
  • Advancing age
  • Family history of colon cancer
  • Polyps in the rectum
  • Pre-existing inflammatory bowel disease, such as ulcerative colitis
  • High fat, low fibre, low calcium diet
  • Obesity

Diagnosis of rectal cancer

  • Rectal cancer is diagnosed using a range of tests including:
  • Rectal examination – the doctor inserts a gloved finger into the rectum and feels for lumps.
  • Faecal occult blood test – faecal matter is examined in the laboratory.
  • Proctoscope or sigmoidoscope – a slender instrument is inserted into the anus to allow the doctor to look at the rectum.
  • Colonoscopy – a longer instrument is inserted (under sedation) to check the rectum and colon.
  • Biopsy – a small tag of tissue is removed and examined in a laboratory for the presence of cancerous cells.
  • Barium enema – special fluid is squirted into the rectum and x-rays are taken.
  • Endorectal ultrasound – an ultrasound device is inserted and pictures taken of the rectum.
  • Magnetic resonance imaging (MRI) – a high-definition scan is used to determine the size and spread of rectal cancer.

Stages of rectal cancer

Rectal cancer is categorised into different stages including:

  • Stage 0 – the cancer is limited to the lining (epithelium) of the rectum.
  • Stage 1 – the cancer has spread to the deeper layers of the rectal lining.
  • Stage 2 – the cancer has spread to tissues beyond the rectum, but not to the lymph nodes in the local area.
  • Stage 3 – the cancer has spread to the lymph nodes in the local area.
  • Stage 4 – the cancer has developed secondary cancers at other sites around the body.

Treatment for rectal cancer

Treatment for rectal cancer depends on its stage, but may include:

  • Surgery – the cancer and associated rectal tissue as well as nearby lymph nodes are removed either through the anus or via an abdominal incision. The rectum is then sewn back together. If a large amount of tissue is removed, it may not be possible to close the rectum and a colostomy will be needed, either temporarily or permanently.
  • Radiation therapy – high doses of precisely targeted radiation are used to kill cancer cells.
  • Chemotherapy – cancer-killing drugs are administered by intravenous injection or by mouth.

There are several specialised centres in most Australian States and Territories that treat rectal cancer. Results from treatment are generally better when treatment is provided by these specialised centres.


Sometimes, so much tissue is removed that the rectum can’t be sewn back together or reattached to the anus. In this case, the bowel is diverted from the anus to a small hole in the abdomen (stoma) and a colostomy bag fitted.

A colostomy bag is made from plastic and is stuck to the stoma with special glue. Wastes are passed into the bag, which is then thrown away and replaced with a fresh one.

A temporary colostomy bag may sometimes be needed while a successfully remodelled rectum heals properly. Less than a third of patients that have an operation for rectal cancer will require colostomy.

When a cure for rectal cancer isn’t possible

If rectal cancer has been diagnosed in its later stages, the cancer may have spread to the point where a cure is no longer possible.

Treatment then focuses on improving quality of life by relieving the symptoms. This is called palliative treatment.

Where to get help

  • Your doctor

Things to remember

  • The rectum makes up the last 20 cm or so of the large intestine.
  • The function of the rectum is to temporarily store faeces.
  • Rectal cancer usually affects people over the age of 50 years, with men more susceptible than women.
  • Treatment includes surgery, chemotherapy and radiation therapy.

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