What are the treatment options for constipation in cancer patients?

Treatment of Constipation in Cancer Patients

For cancer patients with constipation, a stepwise approach starting with osmotic and stimulant laxatives is recommended, with methylnaltrexone reserved for opioid-induced constipation that doesn't respond to standard therapy. 1

Assessment and Diagnosis

• All cancer patients should be evaluated for constipation with questions to determine possible causes 1
• Physical examination should include abdominal examination, perineal inspection, and digital rectal examination (DRE) 1
• Investigations are not routinely necessary, but if clinically suspected, calcium levels and thyroid function should be checked 1
• Plain abdominal X-ray may be useful to image the extent of fecal loading and exclude bowel obstruction 1
• Rule out impaction, obstruction, and other treatable causes such as hypercalcemia, hypokalemia, hypothyroidism, and diabetes mellitus 1

Prevention and Self-Care Strategies

• Ensure privacy and comfort to allow normal defecation 1
• Proper positioning (using a small footstool to assist gravity) 1
• Increase fluid intake and physical activity within patient limits 1
• Maintain adequate dietary fiber intake when appropriate 1
• Anticipatory management of constipation when opioids are prescribed 1
• Abdominal massage may help reduce gastrointestinal symptoms, particularly in patients with neurogenic problems 1

Pharmacological Management

First-Line Options

• Osmotic Laxatives (preferred option) 1:

  • Polyethylene glycol (PEG/Macrogol): Virtually no net gain or loss of sodium and potassium 1
  • Lactulose: May cause latency of 2-3 days before onset of effect; can cause nausea and abdominal discomfort 1
  • Magnesium salts: Use cautiously in renal impairment due to risk of hypermagnesemia 1

• Stimulant Laxatives (preferred option) 1:

  • Senna, cascara: Best taken in the evening with the aim of producing a normal stool next morning 1
  • Bisacodyl, sodium picosulfate: Recommended for short-term use in refractory constipation 1

For Opioid-Induced Constipation

• All patients receiving opioid analgesics should be prescribed a concomitant laxative unless contraindicated by pre-existing diarrhea 1
• Prophylactic treatment with a stimulant laxative to increase bowel motility, with stool softeners as indicated 1
• Bulk laxatives such as psyllium are not recommended for opioid-induced constipation 1
• Combined opioid/naloxone medications can reduce the risk of opioid-induced constipation 1

For Persistent Constipation

• Add bisacodyl 10-15 mg, 2-3 times daily, with a goal of one non-forced bowel movement every 1-2 days 1
• If constipation persists, consider adding other laxatives such as:
  • Rectal bisacodyl twice daily 1
  • Oral polyethylene glycol, lactulose, magnesium hydroxide, or magnesium citrate 1
• If gastroparesis is suspected, add a prokinetic agent such as metoclopramide 1

Management of Fecal Impaction

• If impaction is observed, use glycerin suppositories or perform manual disimpaction 1
• Suppositories and enemas are preferred first-line therapy when DRE identifies a full rectum or fecal impaction 1
• In the absence of suspected perforation or bleeding, disimpaction (usually through digital fragmentation and extraction of stool) should be followed by a maintenance bowel regimen to prevent recurrence 1

Refractory Constipation

• For opioid-induced constipation that has not responded to standard laxative therapy, consider methylnaltrexone 0.15 mg/kg subcutaneously every other day (no more than once per day) 1, 2
• For patients with advanced illness or pain caused by active cancer who require opioid dosage escalation for palliative care, methylnaltrexone injection is specifically indicated 2
• Dosage adjustment is required for patients with moderate to severe renal impairment 2

Special Considerations for Elderly Cancer Patients

• Pay particular attention to the assessment of elderly patients 1
• Ensure access to toilets, especially in cases of decreased mobility 1
• Provide dietetic support 1
• Manage known decrease in food intake 1

Cautions and Contraindications

• Enemas are contraindicated in patients with neutropenia, thrombocytopenia, paralytic ileus, intestinal obstruction, recent colorectal or gynecological surgery, recent anal or rectal trauma, severe colitis, toxic megacolon, undiagnosed abdominal pain, or recent pelvic radiotherapy 1
• Methylnaltrexone can cause serious side effects including intestinal perforation, severe diarrhea, and opioid withdrawal symptoms 2
• Do not use methylnaltrexone in patients with bowel obstruction or history of bowel blockage 2

Evidence suggests that a sennosides-only protocol may be more effective than combining sennosides with docusate in hospitalized cancer patients 3, highlighting that more is not always better when it comes to laxative combinations.