Nausea, Vomiting (Emesis), Constipation, and Bowel Obstruction in Advanced Cancer
Nausea and vomiting (emesis) (N&V) are common symptoms in patients with advanced cancer, occurring in approximately 21% to 68% of these patients.[1,2] The underlying pathophysiology and treatment differs somewhat from nausea related to radiation treatment or chemotherapy. Chronic nausea can significantly impair a patient's quality of life.
The site of origin of a histologically documented carcinoma is not identified clinically in approximately 3% of patients; this situation is often referred to as carcinoma of unknown primary (CUP) origin or occult primary malignancy.[1,2,3,4,5,6]
The definition of a CUP varies from study to study; however, at a minimum, this determination should include a biopsy of the tumor and a thorough history and complete physical examination that includes head and neck, rectal, pelvic, and breast examinations;...
Chronic nausea in the advanced cancer setting is often multifactorial in origin.[1,2,3] Medications, including some that are frequently prescribed in this setting—such as opioids, nonsteroidal anti-inflammatory drugs, and selective serotonin reuptake inhibitor (SSRI) antidepressants—may be responsible.
In the case of opioids, nausea frequently resolves spontaneously a few days after initiation of treatment. In some cases, however, it may persist. Nausea resulting from the accumulation of active opioid metabolites (morphine-6-glucuronide) has been described, and patients with impaired renal function may be at increased risk. Opioids invariably produce constipation if prophylactic measures are not taken (namely, the use of a regular laxative regimen), and constipation is one of the most common causes of nausea in patients with advanced cancer.[5,6,7,8]
Opioid-induced gastrointestinal (GI) motility problems may compound the problem of diminished GI motility that many patients experience as part of the anorexia-cachexia syndrome of advanced cancer. The autonomic dysfunction that often accompanies this syndrome results in decreased GI motility, early satiety, and chronic nausea.[9,10,11] Other causes of chronic nausea in these patients include the following:
Nausea, like many other symptoms, may have psychological undercurrents that either exacerbate or induce chronic nausea.
A comprehensive history that includes determining the frequency and effectiveness of bowel movements and laxative therapy is essential. Concurrent medications should be reviewed, and the frequency and nature of N&V should be documented. Examination should attempt to exclude bowel obstruction, fecal impaction, dehydration, and raised intracranial pressure. History and physical examination are poor at determining the extent of constipation. A plain flat-plate x-ray of the abdomen can be very useful to this end. Surgical x-ray views of the abdomen may be helpful if a bowel obstruction is suspected. Investigations to determine blood levels of electrolytes, calcium, and renal parameters may also be helpful.
Management centers on identifying the underlying causes, addressing these when possible, and controlling the symptoms.[1,2] A basic working knowledge of the emetic pathways and identification of possible underlying causes should guide antiemetic selection.
Multiple antiemetic regimens have been proposed for the management of chronic nausea in the advanced cancer setting. Prospective studies comparing one regimen with another are lacking. Metoclopramide or domperidone are generally recommended as first-line agents because they improve GI motility and act on the chemoreceptor trigger zone (as a result of their antidopaminergic properties). Metoclopramide can be administered orally or parenterally (subcutaneously or intravenously [IV]) at doses of 10 mg, 4 times a day, or on an every-4-hour basis, depending on the severity of the nausea. Rescue doses should also be ordered on an as-needed basis to manage the episodic worsening of nausea that may occur.