Prevention and control of nausea and vomiting are paramount in the treatment of cancer patients. Nausea and vomiting can result in serious metabolic derangements, nutritional depletion and anorexia, deterioration of patients' physical and mental status, esophageal tears, fractures, wound dehiscence, withdrawal from potentially useful and curative antineoplastic treatment, and degeneration of self-care and functional ability. Despite advances in pharmacologic and nonpharmacologic management, nausea and vomiting remain two of the more distressing and feared side effects to cancer patients and their families, and incidence may be underestimated by physicians and nurses.[1,2,3,4,5]

Introduction

Nausea is a subjective phenomenon of an unpleasant, wavelike sensation experienced in the back of the throat and/or the epigastrium that may or may not culminate in vomiting. Vomiting is the forceful expulsion of the contents of the stomach, duodenum, or jejunum through the oral cavity. Retching is gastric and esophageal movements of vomiting without expulsion of vomitus and is also referred to as dry heaves.

Classifications

Various classifications of nausea and vomiting (N&V) have been used,[1,6] including acute, delayed, late or persistent, chronic, anticipatory, breakthrough, or refractory, as well as distinctions related to type of treatment (e.g., chemotherapy- or radiation-induced), and clinical course (e.g., advanced or terminal disease).[7,8] Despite this variety, the most commonly described types are acute, delayed, and anticipatory chemotherapy-induced N&V; and chronic N&V in advanced cancer patients. Although there are no standard definitions, the following are commonly used to classify the different types.

• ACUTE NAUSEA AND VOMITING (OR EMESIS): N&V experienced during the first 24-hour period after chemotherapy administration is considered acute N&V.[1]
• DELAYED (OR LATE) NAUSEA AND VOMITING (OR EMESIS): N&V that occurs more than 24 hours after chemotherapy administration is considered delayed, or late, N&V. Delayed N&V is associated with cisplatin, cyclophosphamide, and other drugs (e.g., doxorubicin and ifosfamide) given at high doses or on 2 or more consecutive days.
• ANTICIPATORY NAUSEA AND VOMITING (ANV): ANV is nausea and/or vomiting that occur prior to the beginning of a new cycle of chemotherapy, in response to conditioned stimuli such as the smells, sights, and sounds of the treatment room. ANV is a classically conditioned response that typically occurs after three or four prior chemotherapy treatments, following which the person experienced acute or delayed N&V.
• CHRONIC NAUSEA AND VOMITING (OR EMESIS) IN ADVANCED CANCER PATIENTS: Chronic nausea and vomiting in the advanced cancer patient is N&V associated with a variety of potential etiologies. A definitive understanding of cause is not well known, nor well researched, but potential causal factors include gastrointestinal, cranial, metabolic, drug-induced (e.g., morphine), cytotoxic chemotherapy, and radiation-induced mechanisms.[9]