Constipation in cancer patients is a symptom that may or may not be symptomatic of an organic condition or a complication of systemic disease or its treatment. One definition of constipation is the "four toos – stools that are too hard, too small, too difficult to expel, and too infrequent". However it must be considered that constipation is relative, referring to a change in bowel habit from the normal for that person. Normal bowel habit may very from twice daily to once every two or three days, hence the lack of a daily bowel movement is not an indication of constipation or the need for a laxative.
Constipation is a very common symptom occurring in cancer patients. It is important that the problem is corrected early as it can become a quite disabling problem and impact severely on your quality of life, as well as lead to serious complications such as bowel obstruction. However, it can be difficult to treat and is often recurrent.
Cancer patients are likely to develop constipation for a number of reasons, including:
- Medications- Morphine-based drugs used by cancer patients for pain relief can cause reduced bowel activity. In addition chemotherapy drugs (anti-cancer agents) can also cause constipation by disrupting nerve signals to the bowel.
- Poor fluid and fibre intake and general decreased diet intake, which is caused by other factors such as nausea, anorexia, depression, inability to swallow and so forth.
- Immobility and/or reduced physical activity.
- Electrolyte abnormalities eg. high calcium levels.
- Certain types of cancer can cause obstruction ie. colorectal cancer.
- Spinal cord tumours and spinal cord compression.
- Some chemotherapy drugs.
The causes of constipation should be ascertained where possible by thorough history taking and examination by a physician. A full history will include details such as the normal bowel habit and how has it changed, previous need for laxative use, medication history, fluid and fibre intake and accessibility of the toilet at home. The examination should include looking for a distended abdomen, feeling the abdomen for masses and listening for bowel sounds. It may be necessary to do a rectal examination to determine if there are faeces in the rectum, the consistency of the faeces and to assess anal tone. Further investigations such as a an abdominal x-ray may be required if clinical signs are suggestive of a bowel obstruction.
One of the best treatments for constipation in cancer patients is to prevent it occuring in the first place. You can help prevent this by ensuring you mantain a healthy diet, drink plenty of fluids and use preventative laxatives as directed by your doctor. Other treatments may not always be suitable. Once constipation is diagnosed, simple non-drug measures that can be undertaken, include increasing fluid and fibre intake as tolerated (fruit juice is useful) and increasing your mobility (pain management, physiotherapy). Bowel function should be regularly reviewed by your doctor, and management adjusted as necessary with regards to diet, laxatives and adjustment of medications.
Prophylactic Laxative Prescribing: Opioids cause constipation by several effects on the gastrointestinal tract, including decreased stomach emptying and slowing peristalsis (gut activity). Studies have shown that nearly all patients will experience constipation whilst on opioid therapy. Your doctor can prescribe a laxative regimen when they start you on opioid analgesics and alter doses according to your requirements. Generally speaking, laxatives may be divided into those which are softeners (most useful when stool is hard) and those which stimulate the bowel and encourage bowel movement. Softeners include docusate (coloxyl), lactulose and sorbitol. Stimulants include bisacodyl and senna.
Established Constipation: Up to a third of patients will continue to require intervention in addition to oral laxatives for their bowels at some point. Often you can self-administer suppositories and/or small enemas at home but if your constipation becomes very severe and more intricate bowel intervention is required, hospitalisation may be required. Your doctor will carefully assess your problem and decide on an appropriate type of laxatives that will overcome the symptoms.
Neurogenic Bowel: Neurogenic bowel is most commonly caused by spinal cord compression although it can be the result of direct nerve root damage. Drug treatment aims to cause evacuation of the bowel every one or two days depending upon your previous normal bowel habit. A typical regimen includes stimulant suppositories on alternate days in addition to oral softening laxatives but will be specifically tailored to your situation.
Overflow Diarrhoea: Paradoxically diarrhoea can be caused by ongoing constipation. This occurs when there is leakage of watery faeces around the blockage. If this occurs you may notice a pattern of constipation and then diarrhoea. This should not be treated with anti-diarrhoeal drugs as they will worsen the problem.
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