Nausea is an unpleasant wavelike feeling in the back of the throat and/or stomach that may or may not result in vomiting. Vomiting is the forceful elimination of the contents of the stomach through the mouth. Retching is the movement of the stomach and esophagus without vomiting and is also called dry heaves. Although treatments have improved, nausea and vomiting continue to be worrisome side effects of cancer therapy. Nausea may be even more distressing for patients than vomiting.

It is very important to prevent and control nausea and vomiting in patients with cancer. Uncontrolled nausea and vomiting can interfere with the patient's ability to receive cancer treatment and care for himself or herself by causing chemical changes in the body, loss of appetite, physical and mental difficulties, a torn esophagus, broken bones, and the reopening of surgical wounds.

Nausea and vomiting that are caused by cancer therapy are classified as follows:

• Anticipatory.
• Acute.
• Delayed.
• Chronic.

Anticipatory nausea and vomiting: If a patient has had nausea and vomiting after the previous 3 or 4 chemotherapy treatments, he or she may experience anticipatory nausea and vomiting. The smells, sights, and sounds of the treatment room may remind the patient of previous episodes and may trigger nausea and vomiting before a new cycle of chemotherapy (or radiation therapy) has even begun.

Acute nausea and vomiting: Usually occurs within 24 hours after beginning chemotherapy.

Delayed nausea and vomiting: Occurs more than 24 hours after chemotherapy. Also called late nausea and vomiting.

Chronic nausea and vomiting: May affect people who have advanced cancer. It is not well understood.

Causes of Nausea

Nausea is controlled by a part of the central nervous system that controls involuntary bodily functions. Vomiting is a reflex controlled by a vomiting center in the brain. Vomiting can be stimulated by various triggers, such as smell, taste, anxiety, pain, motion, poor blood flow, irritation, or changes in the body caused by inflammation.

The most common causes of nausea and vomiting are:

• Chemotherapy drugs.
• Radiation therapy directed at the gastrointestinal (GI) tract, liver, or brain.

Nausea and vomiting are more likely to occur if the patient:

• Experienced severe episodes of nausea and vomiting after past chemotherapy sessions.
• Is female.
• Is younger than 50 years.
• Has a fluid and/or electrolyte imbalance (hypercalcemia, dehydration, or an excess of fluid in the body's tissues).
• Has a tumor in the GI tract, liver, or brain.
• Has constipation.
• Is receiving certain drugs.
• Has an infection or blood poisoning.
• Has kidney disease.
• Experiences anxiety.

Anticipatory Nausea and Vomiting

Anticipatory nausea and vomiting occur after the patient has undergone several cancer treatments. It occurs in response to triggers, such as odors in the therapy room. For example, a person who begins chemotherapy and smells an alcohol swab at the same time, may later experience nausea and vomiting at the smell of alcohol alone. Patients usually do not experience nausea and/or vomiting before or during chemotherapy until after they have received several courses of treatment. The following factors may help predict which patients are more likely to experience anticipatory nausea and vomiting:

• Being younger than 50 years.
• Being female.
• The severity of nausea and vomiting after the last chemotherapy session.
• Feeling warm or hot after the last chemotherapy session.
• A history of motion sickness.
• Feeling dizzy or lightheaded after chemotherapy.
• Sweating after the last chemotherapy session.
• Experiencing weakness after the last chemotherapy session.
• Having a high level of anxiety.
• The type of chemotherapy (some are more likely to cause nausea and vomiting).
• Having morning sickness during pregnancy.

Acute Nausea and Vomiting

Chemotherapy is the most common treatment-related cause of nausea and vomiting. The drug, dose, schedule of administration, route, and factors that are unique to the patient all determine how often nausea occurs and how severe it will be. Usually, these symptoms can be prevented or controlled.

Acute nausea and vomiting are more likely to occur in patients who:

• Have experienced nausea and vomiting after previous chemotherapy sessions.
• Are female.
• Drink little or no alcohol.
• Are young.

Tags: Cancer

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